[Drakelist] TR-4C S meter meter zero
Help! - Original Message - With no incoming signals, including crystal calibrator, and with C-130 adjusted for equal sounding white noise when switching between Lower and Upper I am unable to zero the S-meter in both sidebands. It will zero with one or the other and then the other is off by 1 to 1 1/2 S units or so. I can adjust C-130 so the S- meter zeros in both sidebands but then the white noise has a different sound in each sideband. My other TR-4CW/RIT works as it should in all respects to S-meter zero, C-130 adjustment, and white noise: sound. I'm starting to think one or both filters may be the root of this evil but do not have a scope t o visually look around. .I'm convinced I'm overlooking something. What might it be? 73 joe k7mks __._,_.___ Reply via web post Reply to sender Reply to group Start a New Topic Messages in this topic (1) Visit Your Group * New Members 6 • Privacy • Unsubscribe • Terms of Use . __,_._,___ ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C S meter meter zero
I've been suspecting my filters are drifting too! A friend of mine had his lower SSB filter go intermittent this weekend. I have a few Drake rigs and the audio is not right coming out of a couple of them. I think the crystals in the filters are drifting and producing weird shaped output curves for the filters. Kind of scares me when you consider new filters will cost around $130 each and you need two of them! Lee, w0vt - Original Message - From: k7...@comcast.net To: drakelist drakelist@zerobeat.net Sent: Monday, February 24, 2014 12:35:58 PM Subject: [Drakelist] TR-4C S meter meter zero Help! - Original Message - With no incoming signals, including crystal calibrator, and with C-130 adjusted for equal sounding white noise when switching between Lower and Upper I am unable to zero the S-meter in both sidebands. It will zero with one or the other and then the other is off by 1 to 1 1/2 S units or so. I can adjust C-130 so the S- meter zeros in both sidebands but then the white noise has a different sound in each sideband. My other TR-4CW/RIT works as it should in all respects to S-meter zero, C-130 adjustment, and white noise: sound. I'm starting to think one or both filters may be the root of this evil but do not have a scope t o visually look around. .I'm convinced I'm overlooking something. What might it be? 73 joe k7mks __._,_.___ Reply via web post Reply to sender Reply to group Start a New Topic Messages in this topic (1) Visit Your Group * New Members 6 Yahoo! Groups • Privacy • Unsubscribe • Terms of Use . __,_._,___ ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C S meter meter zero
It’s a common problem with all of the TR-4 models, usually the LSB filter ( LSB on 80 meters ). 73, Gary http://home.roadrunner.com/~w8pu R-4A T4-X R-4B T4-XB R-4C T4-XC MS-4 L-4B RCS-4 2A 2B 2C 2NT 2CQ 2AS 4-LF TR-4 TR-4C TR-4CW/RIT RV-4C MC-4 TR-7 RV-7 CW-75 MS-7 WH-7 W-4 WV-4 MN-2700 MN-4C MN-2000 UV-3 PS-3 TR-22C TR-33C AA-10 AC-10 MMK-22 TR-6 PRN1000 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C USB/LSB C-130 Adjustment
Am struggling with adjustment of C-130 for equal pitch of noise w/ the LSB and USB front panel switch per the manuals 9 MHz oscillator adjustments - Section 5-9. Adjusting C-130 also seems to affect S-meter zero in USB and LSB. My other xcvr, a TR-4CW/RIT, also appears to behave the same way. I suspect I'm overlooking something, perhaps the aging of the filters, and will welcome your thoughts. Many thanks, Joe k7mks ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Relay
Try Relay Specialists I think you can still order a new one. Tim WB8UHZ On Tuesday, November 26, 2013 10:09 AM, k7...@comcast.net k7...@comcast.net wrote: Looks like my relay has an open coil. Does anyone have a part unit or a source where I might purchase a new relay. Thank you, joe k7mks ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Relay
All, the relay for the TR4C and the T4XC are the same relay. You can purchase the relay from Mouser Electronics. www.mouser.com The Mouser part number is: 655-R10-E1Y4-V2.5K The part cost is $27.64 Mouser ships same day and they have no minimum order requirements. Happy Thanksgiving to all,Ron / WB4HFN From: drakelist-boun...@zerobeat.net [mailto:drakelist-boun...@zerobeat.net] On Behalf Of amfone Sent: Wednesday, November 27, 2013 8:13 AM To: k7...@comcast.net; drakelist Subject: Re: [Drakelist] TR-4C Relay Try Relay Specialists I think you can still order a new one. Tim WB8UHZ On Tuesday, November 26, 2013 10:09 AM, k7...@comcast.net k7...@comcast.net wrote: Looks like my relay has an open coil. Does anyone have a part unit or a source where I might purchase a new relay. Thank you, joe k7mks ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C Relay
Looks like my relay has an open coil. Does anyone have a part unit or a source where I might purchase a new relay. Thank you, joe k7mks ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C for sale I have a TR-4C that I need to sell to help pay medical bills.
Thanks for your time. I would like to get $300.00 for the set. TR4-C AC4-D supply MS-4 speaker This radio also has the HV cap replacement mod partly installed and working. Voltages appear to be good.Mainly cosmetic . Also appears to have a dirty band switch. 73 de WB9AUJ John Vodenik 1-513-`398-5968 any time ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C VOX--Oops!
Hi, all: I should do a better job of proofreading before pressing the Send button! The summary of the changes should have referenced R135 (not R133) in the both cases. I apologize if there was any confusion. 73, Bob K9JU ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C Parts needed
Hi All, Need a top for the PA finals cage and a new Plate control shaft for a TR-4C.Anyone have one to spare ? 73 es thanks, Gene K1NR - Web mail provided by NuNet, Inc. The Premier National provider. http://www.nni.com/ ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Parts needed
_eugeneb@nni.com_ (mailto:euge...@nni.com) writes: Need a top for the PA finals cage and a new Plate control shaft for a TR-4C.Gene K1NR Gene, Some of the TR4/4c's didn't have a top for the finals. In addition some of the final tube heights won't allow the cover which I think is why some may not be there. As far as the shaft let me look tonight. Carl WD8NHK ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Parts needed
Cal, Appreciate the info. It appears that the components in my TR-4C will fit with a top. I will look again. Thanks for checking on the shaft. 73 Gene K1NR On Sat, 3 Nov 2012 14:46:20 -0400 (EDT) gypsym...@aol.com wrote: _eugeneb@nni.com_ (mailto:euge...@nni.com) writes: Need a top for the PA finals cage and a new Plate control shaft for a TR-4C.Gene K1NR Gene, Some of the TR4/4c's didn't have a top for the finals. In addition some of the final tube heights won't allow the cover which I think is why some may not be there. As far as the shaft let me look tonight. Carl WD8NHK - Web mail provided by NuNet, Inc. The Premier National provider. http://www.nni.com/ ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C S-Meter
S-Meter is now working better and RX sensitivity is better after poking and tighting. I think the relay or fuse lamp socket was not making good contact. Tightened a bunch of screws. S-Meter only goes to half scale in XMIT. I found this problem on and R4b and found what I did on it a few years ago so maybe it is a similar part on the TR-4c. S-Meter zero is normal and it reads about right now on signals . Below is from the list Archives of what I did with he R4b. The archive is really useful. Received new Bias Filter Cap yesterday and installed it today. R4B is now working again. Thanks to help from the list again. The replacement used was a Sprauge Atom 10uf @500V which is a bit overkill but was the closest I could find from either Digi Key or AES on the day I ordered. Bias and S-Meter alignment now work perfectly. It was very interesting to note the difference in the 'magic eye' readings for the leakage tests on the old vs. new cap when testing on the old Heath C-3 meter. The eye would close down about half way on the 150V leakage test on the old filter cap and did not move at all on the new 500v cap. It sort of a tight fit and I had to ream out the holes in the p/s board a bit with my knife in order to fit the larger diameter leads on the new filter. Muting now puts the meter up to 60 over and the 40 over at 15V sets up nicely. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C S-Meter
Paul - Nope! Entirely different circuit. The S-Meter in the T-R4C is also the ALC (transmit AVC) indicator. It will read 'upscale' in transmit showing the ALC is operating. Adjust GAIN control while speaking until meter kicks up slightly for maximum output. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Paul Gerhardt wrote: S-Meter is now working better and RX sensitivity is better after poking and tighting. I think the relay or fuse lamp socket was not making good contact. Tightened a bunch of screws. S-Meter only goes to half scale in XMIT. I found this problem on and R4b and found what I did on it a few years ago so maybe it is a similar part on the TR-4c. S-Meter zero is normal and it reads about right now on signals . Below is from the list Archives of what I did with he R4b. The archive is really useful. Received new Bias Filter Cap yesterday and installed it today. R4B is now working again. Thanks to help from the list again. The replacement used was a Sprauge Atom 10uf @500V which is a bit overkill but was the closest I could find from either Digi Key or AES on the day I ordered. Bias and S-Meter alignment now work perfectly. It was very interesting to note the difference in the 'magic eye' readings for the leakage tests on the old vs. new cap when testing on the old Heath C-3 meter. The eye would close down about half way on the 150V leakage test on the old filter cap and did not move at all on the new 500v cap. It sort of a tight fit and I had to ream out the holes in the p/s board a bit with my knife in order to fit the larger diameter leads on the new filter. Muting now puts the meter up to 60 over and the 40 over at 15V sets up nicely. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Filament Voltage
Bob, If you feel that the voltage are too low for you, find an old cheap 3 to 4 amp car battery charger (typically 24 volt center tapped for 12 volt battery). Then wire the transformer with the primary on the 230 volts, and the secondary boosting that voltage. Assume 230, plus a 12 volt (half of secondary) gives you 242 volts. 1% over voltage vs 10% under voltage. Basically, you need a transformer for boosting, which has a secondary current rating of the full load of the Drake transformer. If I recall correctly that is about 4ish amps on 240 Volts. Since you are not at full load all the time, a little under rated will work. Don't be running RTTY or other high demand modes with an under rated transformer though. This is making an auto-transformer. This idea is being used a lot with old broadcast receiver protectors. Those radios were made in a day when 105-110 volts were normal in the US, vs the 120-125 volts common today. The idea in this case is to buck the input voltage to a lower value. Good luck, and let us know what you decide and what your results are. 73, Ron WD8SBB --- On Sun, 10/9/11, jeffers...@xtra.co.nz jeffers...@xtra.co.nz wrote: From: jeffers...@xtra.co.nz jeffers...@xtra.co.nz Subject: [Drakelist] TR-4C Filament Voltage To: drakelist@zerobeat.net Date: Sunday, October 9, 2011, 11:12 PM The filament voltage on my TR-4C is just under 6V at the tube filament pin. The Drake AC-4 is wired for 120/240V, but the Line Voltage in New Zealand is 230V. Hence, I presume, this is the reason for lower filament voltage, and probably lower HV on the plates. I suppose this means lower electron flow and less output power (Not yet determined). The only solution that I can think of is to replace the Transformer with a 230V Primary winding (Hardly worthwhile ??). Any comments please. Bob ZL2AAQ. -Inline Attachment Follows- ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Filament Voltage
Bob, Use a filament transformer with a secondary current rating equal to the full load current of the TR-4C as an autotransformer to raise the voltage. If you can find a single transformer with two five volt windings, you can use them in series to get 10 volts, or you could use two five volt transformers. 73, Bob AD3K From: drakelist-boun...@zerobeat.net [mailto:drakelist-boun...@zerobeat.net] On Behalf Of jeffers...@xtra.co.nz Sent: Sunday, October 09, 2011 11:12 PM To: drakelist@zerobeat.net Subject: [Drakelist] TR-4C Filament Voltage The filament voltage on my TR-4C is just under 6V at the tube filament pin. The Drake AC-4 is wired for 120/240V, but the Line Voltage in New Zealand is 230V. Hence, I presume, this is the reason for lower filament voltage, and probably lower HV on the plates. I suppose this means lower electron flow and less output power (Not yet determined). The only solution that I can think of is to replace the Transformer with a 230V Primary winding (Hardly worthwhile ??). Any comments please. Bob ZL2AAQ. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C filament Voltage
Hi, Bob - I wouldn't worry much about the 230 vs 240 V difference. Back when the Drakes were made, most line voltage in the US were assumed to be 115 VAC anyway. Since 115 is half 230 you should be spot-on. (I suspect the higher voltages we now have in the US may slightly contribute to the transformers running warmer). I can't recall if you folks in N.Z. use 50 or 60 Hz. I found during my time working on power supplies years ago that this difference would have more of an effect on the equipment (it causes transformers rated for 60 Hz to run much warmer at 50 Hz) than a change in line voltage (within reason). I can also recall testing lots of equipment that was designed to run at least +/- 10% of rated line voltage. Tube equipment, in general, tends to be less fussy. I'd try firing it up with what you have and measuring your power out. 73, Steve, W1ES/4 On Behalf Of jeffers...@xtra.co.nz Sent: Sunday, October 09, 2011 11:12 PM To: drakelist@zerobeat.net Subject: [Drakelist] TR-4C Filament Voltage The filament voltage on my TR-4C is just under 6V at the tube filament pin. The Drake AC-4 is wired for 120/240V, but the Line Voltage in New Zealand is 230V. Hence, I presume, this is the reason for lower filament voltage, and probably lower HV on the plates. I suppose this means lower electron flow and less output power (Not yet determined). The only solution that I can think of is to replace the Transformer with a 230V Primary winding (Hardly worthwhile ??). Any comments please. Bob ZL2AAQ. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C Filament Voltage
The filament voltage on my TR-4C is just under 6V at the tube filament pin. The Drake AC-4 is wired for 120/240V, but the Line Voltage in New Zealand is 230V. Hence, I presume, this is the reason for lower filament voltage, and probably lower HV on the plates. I suppose this means lower electron flow and less output power (Not yet determined). The only solution that I can think of is to replace the Transformer with a 230V Primary winding (Hardly worthwhile ??). Any comments please. Bob ZL2AAQ. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Garey, I am not offended by any questions about whether I am doing things correctly. I need reality checks occasionally. I checked over my notes that I am keeping and see that the current did NOT dip across R45 but acted just like the RF output and peaked about midrange and fell off on both sides. I want to go back and redo some of these measurements. I removed the RF output switch on the LOAD control to make better resistance measurements on the switch. I found the contacts to be unstable out of circuit, so I am going to replace it. Maybe the connection to the LOAD shaft would hold the switch in the right position to make good contact. I don't think this is responsible for the problem, but it can't hurt to replace it. I am going to go back and recheck some of the measurements and make sure that I am tuning per the manual. Richard - Original Message - From: Garey Barrell k4...@mindspring.com Cc: drakelist Drakelist@zerobeat.net Sent: Saturday, July 16, 2011 10:23 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I just another couple of thoughts. Looking back through the million or so messages regarding this problem, I asked if the voltage across R45 'dipped' when you rotated the PLATE control, and you replied that it did NOT, rather it peaked just like the RF output, falling off on either side. That's just not right!! :-) Please don't be offended, but you ARE tuning the PLATE control and NOT the RF TUNE control.? Just remember, 'We do this for fun ... We do this for fun ...:-) 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Garey, et al The PA tubes are Sylvania 6JB6, checked on a Hickok 600A and test good. I have seen no color to the plates of the finals. I have been doing all testing on 40 M. I came to suspect one of the sideband filters so I tried 80, 40 and 20 M., both upper and lower sideband to see what happened. I got output in excess of 125 W. to the dummy load in all cases. The cables to the wattmeter and dummy load are OK, the dummy load (switched to a Bird 8201) is OK. I took the lid off of the PA cage and placed an all purpose telescoping antenna next to the cage and ran the input into an HP spectrum analyzer. I got a very nice signal at 7.3 MHz and also very nice signals at 14, 21 and 28 MHz. There was no sign of any other oscillation of the finals. I did notice hash from the laptop computer switching power supply which went away when I unplugged it. Replacing and grounding the PA lid removed the extraneous harmonics at 14, 21 and 28 MHz. I also listened to the signal with another receiver and had a very clear sounding tone with no other noise up and down the dial. I varied the TR-4C VFO to make sure I was listening to the correct signal. I did measure the lead resistance of the Fluke leads. It is about 0.15 ohms, so the resistance of R45 will be about 2.25 ohms, closer to the nominal value. I don't think anything is wrong with the output circuitry. If there was, how could I be measuring power out to the dummy load? The wattmeter is a Swan 3000. I am not absolutely certain that it is working OK. I suppose I should try the light bulb technology that I used as a novice back when I knew it all. Now I have some reasonable equipment and don't know anything. Now, the last item puzzles me. I measured the ANT output to ground (SO-239) and it was 1.4 ohms, no way near 2.2 Megohms. RFC 7 goes to ground right at the SO-239. I would expect the DC resistance of the choke to be more than 1.4 ohms but less than 2.2 Megohms. Are we getting closer to an answer or just more confusion (I know it is the latter for me)? Awaiting further task assignments. I appreciate all the help. 73 Richard - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Thursday, July 14, 2011 10:27 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - OK. As others have said, we are missing something fundamental, as transmitters just do not do this!! :-) Verifying that the PA tubes ARE 6JB6 is a good idea. The Simpson is more than adequate for all but very low resistance readings, 2 - 15 ohm resistors and the voltage across them. You haven't confirmed which band you are using for test purposes. I suggest 40M. Are the PA plates showing any color that you have seen? Listen on another receiver and determine if you can hear the TR-4C on the frequency indicated by the dial reading. Once you find the signal, does it vary with PTO adjustment as expected? Since we have already measured the voltage across the three Cathode resistors and determined that they are approximately equal, nothing is gained by the risky (dangerous) measurement of 'plate' current. There is no place else for the current through R45 to come from other than the plate supply, so
Re: [Drakelist] TR-4C Bias Adjustment
Garey et al, I made resistance measurements on the RF Output switch on the LOAD shaft with the switch in place and wires and resistor attached. I got steady readings but wasn't satisfied. I removed the switch and made measurements just on the switch contacts. The open positions were obviously open, but the shorting functions of the switch were unstable. I replaced the switch with the only thing that I had which was a slide switch with snap-and-remain-in-position, not spring loaded for easy return. However, the LOAD shaft spring is strong enough to return the switch. EUREKA The old switch mechanism must have been locking the circuit into the RF output measurement mode. I can now adjust the bias current with the switches set in the required position. However, I can also adjust the bias current with the SIDEBAND switch set in the X position. Question 1Is this normal? I can also properly tune the transmitter. The PLATE control dips current like it should. The RF output adjusts like it should. I can tune and load the transmitter to 440 mA plate current with 185 W output on 40 M. (7.164 MHz.). I have not tried any other frequency. When I activate the mike switch I see the bias or idle current on the plate meter. Question 2Is this normal? When I huff into the mike, the plate current huffs with me. I have no operating experience with the TR-4C, so I don't know the answers to these two questions. I have a proper switch on order. A new item popped up though. When I just ever-so-slightly twist the chassis, the volume level on the speaker drops to about 20 %. I don't know what else might be affected. If I flex the chassis slightly, the volume comes back. If I press the mike switch or activate the key, which activates the relay, the volume level comes back. So it doesn't necessarily take flexure to bring it back. I am thinking bad solder joint somewhere from my continually flexing the chassis in turning it over repeatedly, or that the relay contacts are not as good as I thought they looked. I have a new relay ordered also. Anyway, the major problem seems to be fixed and I can get it on the air. Garey, I thank you very much for your help and all the others who chipped in with suggestions. The Drakelist sure works. Richard - Original Message - From: Garey Barrell k4...@mindspring.com To: Donley donley...@comcast.net Cc: drakelist Drakelist@zerobeat.net Sent: Monday, July 18, 2011 11:28 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - OK. Good idea. Sometimes it helps to just step back and look at the simple things again! :-) For 'normal' operation of the PA, with the LOAD control at minimum, adjust the PLATE control while monitoring the voltage across R45. The voltage should 'dip' at about the same place the output 'peaks'. IF you were to adjust the RF TUNE control, you _would_ see the output _AND_ R45 voltage both peak near the center and fall off on both sides. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Garey, I am not offended by any questions about whether I am doing things correctly. I need reality checks occasionally. I checked over my notes that I am keeping and see that the current did NOT dip across R45 but acted just like the RF output and peaked about midrange and fell off on both sides. I want to go back and redo some of these measurements. I removed the RF output switch on the LOAD control to make better resistance measurements on the switch. I found the contacts to be unstable out of circuit, so I am going to replace it. Maybe the connection to the LOAD shaft would hold the switch in the right position to make good contact. I don't think this is responsible for the problem, but it can't hurt to replace it. I am going to go back and recheck some of the measurements and make sure that I am tuning per the manual. Richard - Original Message - From: Garey Barrell k4...@mindspring.com Cc: drakelist Drakelist@zerobeat.net Sent: Saturday, July 16, 2011 10:23 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I just another couple of thoughts. Looking back through the million or so messages regarding this problem, I asked if the voltage across R45 'dipped' when you rotated the PLATE control, and you replied that it did NOT, rather it peaked just like the RF output, falling off on either side. That's just not right!! :-) Please don't be offended, but you ARE tuning the PLATE control and NOT the RF TUNE control.? Just remember, 'We do this for fun ... We do this for fun ...:-) 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Garey, et al The PA tubes are Sylvania 6JB6, checked on a Hickok 600A and test good. I have seen no color to the plates of the finals. I have been doing all testing on 40 M. I came
Re: [Drakelist] TR-4C Bias Adjustment
Richard - I _TOLD_ you it would be something simple that we missed... :-) How many times did we trace that circuit out? Yes, IDLE current can be measured in either SIDEBAND as long as the relay is closed, by keying the PTT. Start by checking the S-Meter when the audio drops. If it holds steady, then probably in the AF section. If the S-Meter drops, then the problem is probably in the IF, or elsewhere. If the S-Meter holds steady, use your screwdriver in the AF OUTPUT area, particularly the small AF Preamp board nearby, and check all the chassis screws for tightness. If they are tight, loosen a fraction and retighten. DeoxIT the headphone jack shorting contacts. If that doesn't fix it, then check surrounding chassis screws. If still there, then go through the entire radio, checking each chassis screw. If ALL are tight, then look at the leads soldered to the PC boards, especially the solid wire jumpers for cracked solder. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Garey et al, I made resistance measurements on the RF Output switch on the LOAD shaft with the switch in place and wires and resistor attached. I got steady readings but wasn't satisfied. I removed the switch and made measurements just on the switch contacts. The open positions were obviously open, but the shorting functions of the switch were unstable. I replaced the switch with the only thing that I had which was a slide switch with snap-and-remain-in-position, not spring loaded for easy return. However, the LOAD shaft spring is strong enough to return the switch. EUREKA The old switch mechanism must have been locking the circuit into the RF output measurement mode. I can now adjust the bias current with the switches set in the required position. However, I can also adjust the bias current with the SIDEBAND switch set in the X position. Question 1Is this normal? I can also properly tune the transmitter. The PLATE control dips current like it should. The RF output adjusts like it should. I can tune and load the transmitter to 440 mA plate current with 185 W output on 40 M. (7.164 MHz.). I have not tried any other frequency. When I activate the mike switch I see the bias or idle current on the plate meter. Question 2Is this normal? When I huff into the mike, the plate current huffs with me. I have no operating experience with the TR-4C, so I don't know the answers to these two questions. I have a proper switch on order. A new item popped up though. When I just ever-so-slightly twist the chassis, the volume level on the speaker drops to about 20 %. I don't know what else might be affected. If I flex the chassis slightly, the volume comes back. If I press the mike switch or activate the key, which activates the relay, the volume level comes back. So it doesn't necessarily take flexure to bring it back. I am thinking bad solder joint somewhere from my continually flexing the chassis in turning it over repeatedly, or that the relay contacts are not as good as I thought they looked. I have a new relay ordered also. Anyway, the major problem seems to be fixed and I can get it on the air. Garey, I thank you very much for your help and all the others who chipped in with suggestions. The Drakelist sure works. Richard - Original Message - From: Garey Barrell k4...@mindspring.com To: Donley donley...@comcast.net Cc: drakelist Drakelist@zerobeat.net Sent: Monday, July 18, 2011 11:28 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - OK. Good idea. Sometimes it helps to just step back and look at the simple things again! :-) For 'normal' operation of the PA, with the LOAD control at minimum, adjust the PLATE control while monitoring the voltage across R45. The voltage should 'dip' at about the same place the output 'peaks'. IF you were to adjust the RF TUNE control, you _would_ see the output _AND_ R45 voltage both peak near the center and fall off on both sides. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Garey, I am not offended by any questions about whether I am doing things correctly. I need reality checks occasionally. I checked over my notes that I am keeping and see that the current did NOT dip across R45 but acted just like the RF output and peaked about midrange and fell off on both sides. I want to go back and redo some of these measurements. I removed the RF output switch on the LOAD control to make better resistance measurements on the switch. I found the contacts to be unstable out of circuit, so I am going to replace it. Maybe the connection to the LOAD shaft would hold the switch in the right position to make good contact. I don't think this is responsible for the problem, but it can't hurt to replace it. I am going to go back and recheck
Re: [Drakelist] TR-4C Bias Adjustment
Richard, Congratulations and thanks for sharing! I learned a lot. I've had two TR-4C's and the both had the similar problem caused by bad relays and the bulb/socket in the RX ant. Kihwal, K9SUL From: Donley donley...@comcast.net To: k4...@mindspring.com Cc: drakelist Drakelist@zerobeat.net Sent: Monday, July 18, 2011 2:23 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Garey et al, I made resistance measurements on the RF Output switch on the LOAD shaft with the switch in place and wires and resistor attached. I got steady readings but wasn't satisfied. I removed the switch and made measurements just on the switch contacts. The open positions were obviously open, but the shorting functions of the switch were unstable. I replaced the switch with the only thing that I had which was a slide switch with snap-and-remain-in-position, not spring loaded for easy return. However, the LOAD shaft spring is strong enough to return the switch. EUREKA The old switch mechanism must have been locking the circuit into the RF output measurement mode. I can now adjust the bias current with the switches set in the required position. However, I can also adjust the bias current with the SIDEBAND switch set in the X position. Question 1 Is this normal? I can also properly tune the transmitter. The PLATE control dips current like it should. The RF output adjusts like it should. I can tune and load the transmitter to 440 mA plate current with 185 W output on 40 M. (7.164 MHz.). I have not tried any other frequency. When I activate the mike switch I see the bias or idle current on the plate meter. Question 2 Is this normal? When I huff into the mike, the plate current huffs with me. I have no operating experience with the TR-4C, so I don't know the answers to these two questions. I have a proper switch on order. A new item popped up though. When I just ever-so-slightly twist the chassis, the volume level on the speaker drops to about 20 %. I don't know what else might be affected. If I flex the chassis slightly, the volume comes back. If I press the mike switch or activate the key, which activates the relay, the volume level comes back. So it doesn't necessarily take flexure to bring it back. I am thinking bad solder joint somewhere from my continually flexing the chassis in turning it over repeatedly, or that the relay contacts are not as good as I thought they looked. I have a new relay ordered also. Anyway, the major problem seems to be fixed and I can get it on the air. Garey, I thank you very much for your help and all the others who chipped in with suggestions. The Drakelist sure works. Richard - Original Message - From: Garey Barrell k4...@mindspring.com To: Donley donley...@comcast.net Cc: drakelist Drakelist@zerobeat.net Sent: Monday, July 18, 2011 11:28 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - OK. Good idea. Sometimes it helps to just step back and look at the simple things again! :-) For 'normal' operation of the PA, with the LOAD control at minimum, adjust the PLATE control while monitoring the voltage across R45. The voltage should 'dip' at about the same place the output 'peaks'. IF you were to adjust the RF TUNE control, you _would_ see the output _AND_ R45 voltage both peak near the center and fall off on both sides. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Garey, I am not offended by any questions about whether I am doing things correctly. I need reality checks occasionally. I checked over my notes that I am keeping and see that the current did NOT dip across R45 but acted just like the RF output and peaked about midrange and fell off on both sides. I want to go back and redo some of these measurements. I removed the RF output switch on the LOAD control to make better resistance measurements on the switch. I found the contacts to be unstable out of circuit, so I am going to replace it. Maybe the connection to the LOAD shaft would hold the switch in the right position to make good contact. I don't think this is responsible for the problem, but it can't hurt to replace it. I am going to go back and recheck some of the measurements and make sure that I am tuning per the manual. Richard - Original Message - From: Garey Barrell k4...@mindspring.com Cc: drakelist Drakelist@zerobeat.net Sent: Saturday, July 16, 2011 10:23 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I just another couple of thoughts. Looking back through the million or so messages regarding this problem, I asked if the voltage across R45 'dipped' when you rotated the PLATE control, and you replied that it did NOT, rather it peaked just like the RF output, falling off on either side. That's just not right!! :-) Please don't be offended, but you
Re: [Drakelist] TR-4C Bias Adjustment
- Original Message - From: Donley donley...@comcast.net To: k4...@mindspring.com Cc: drakelist Drakelist@zerobeat.net Sent: Monday, July 18, 2011 12:23 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Garey et al, I made resistance measurements on the RF Output switch on the LOAD shaft with the switch in place and wires and resistor attached. I got steady readings but wasn't satisfied. I removed the switch and made measurements just on the switch contacts. The open positions were obviously open, but the shorting functions of the switch were unstable. I replaced the switch with the only thing that I had which was a slide switch with snap-and-remain-in-position, not spring loaded for easy return. However, the LOAD shaft spring is strong enough to return the switch. EUREKA Congratulations and halilulia! -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Richard - I just noticed your description of the slide switch. The original is NOT spring loaded, just a standard two position slide switch. The spring steel 'hairpin' on the LOAD shaft is all that is necessary to switch it back and forth. 73, Garey - K4OAH Glen Allen, VA - Original Message - From: Donley donley...@comcast.net Garey et al, I made resistance measurements on the RF Output switch on the LOAD shaft with the switch in place and wires and resistor attached. I got steady readings but wasn't satisfied. I removed the switch and made measurements just on the switch contacts. The open positions were obviously open, but the shorting functions of the switch were unstable. I replaced the switch with the only thing that I had which was a slide switch with snap-and-remain-in-position, not spring loaded for easy return. However, the LOAD shaft spring is strong enough to return the switch. EUREKA ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
An interesting follow-up question is why did the r45 viltage not dip? Curt KU8L Garey Barrell wrote: Richard - I _TOLD_ you it would be something simple that we missed... :-) How many times did we trace that circuit out? Yes, IDLE current can be measured in either SIDEBAND as long as the relay is closed, by keying the PTT. Start by checking the S-Meter when the audio drops. If it holds steady, then probably in the AF section. If the S-Meter drops, then the problem is probably in the IF, or elsewhere. If the S-Meter holds steady, use your screwdriver in the AF OUTPUT area, particularly the small AF Preamp board nearby, and check all the chassis screws for tightness. If they are tight, loosen a fraction and retighten. DeoxIT the headphone jack shorting contacts. If that doesn't fix it, then check surrounding chassis screws. If still there, then go through the entire radio, checking each chassis screw. If ALL are tight, then look at the leads soldered to the PC boards, especially the solid wire jumpers for cracked solder. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Garey et al, I made resistance measurements on the RF Output switch on the LOAD shaft with the switch in place and wires and resistor attached. I got steady readings but wasn't satisfied. I removed the switch and made measurements just on the switch contacts. The open positions were obviously open, but the shorting functions of the switch were unstable. I replaced the switch with the only thing that I had which was a slide switch with snap-and-remain-in-position, not spring loaded for easy return. However, the LOAD shaft spring is strong enough to return the switch. EUREKA The old switch mechanism must have been locking the circuit into the RF output measurement mode. I can now adjust the bias current with the switches set in the required position. However, I can also adjust the bias current with the SIDEBAND switch set in the X position. Question 1Is this normal? I can also properly tune the transmitter. The PLATE control dips current like it should. The RF output adjusts like it should. I can tune and load the transmitter to 440 mA plate current with 185 W output on 40 M. (7.164 MHz.). I have not tried any other frequency. When I activate the mike switch I see the bias or idle current on the plate meter. Question 2Is this normal? When I huff into the mike, the plate current huffs with me. I have no operating experience with the TR-4C, so I don't know the answers to these two questions. I have a proper switch on order. A new item popped up though. When I just ever-so-slightly twist the chassis, the volume level on the speaker drops to about 20 %. I don't know what else might be affected. If I flex the chassis slightly, the volume comes back. If I press the mike switch or activate the key, which activates the relay, the volume level comes back. So it doesn't necessarily take flexure to bring it back. I am thinking bad solder joint somewhere from my continually flexing the chassis in turning it over repeatedly, or that the relay contacts are not as good as I thought they looked. I have a new relay ordered also. Anyway, the major problem seems to be fixed and I can get it on the air. Garey, I thank you very much for your help and all the others who chipped in with suggestions. The Drakelist sure works. Richard - Original Message - From: Garey Barrell k4...@mindspring.com To: Donley donley...@comcast.net Cc: drakelist Drakelist@zerobeat.net Sent: Monday, July 18, 2011 11:28 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - OK. Good idea. Sometimes it helps to just step back and look at the simple things again! :-) For 'normal' operation of the PA, with the LOAD control at minimum, adjust the PLATE control while monitoring the voltage across R45. The voltage should 'dip' at about the same place the output 'peaks'. IF you were to adjust the RF TUNE control, you _would_ see the output _AND_ R45 voltage both peak near the center and fall off on both sides. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Garey, I am not offended by any questions about whether I am doing things correctly. I need reality checks occasionally. I checked over my notes that I am keeping and see that the current did NOT dip across R45 but acted just like the RF output and peaked about midrange and fell off on both sides. I want to go back and redo some of these measurements. I removed the RF output switch on the LOAD control to make better resistance measurements on the switch. I found the contacts to be unstable out of circuit, so I am going to replace it. Maybe the connection to the LOAD shaft would hold the switch in the right position to make good
Re: [Drakelist] TR-4C Bias Adjustment
Thanks to all involved for posting all the to and fro in this thread. It's what makes reflectors so interesting and useful! 73 John K5MO ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Richard - I just another couple of thoughts. Looking back through the million or so messages regarding this problem, I asked if the voltage across R45 'dipped' when you rotated the PLATE control, and you replied that it did NOT, rather it peaked just like the RF output, falling off on either side. That's just not right!! :-) Please don't be offended, but you ARE tuning the PLATE control and NOT the RF TUNE control.? Just remember, 'We do this for fun ... We do this for fun ...:-) 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Garey, et al The PA tubes are Sylvania 6JB6, checked on a Hickok 600A and test good. I have seen no color to the plates of the finals. I have been doing all testing on 40 M. I came to suspect one of the sideband filters so I tried 80, 40 and 20 M., both upper and lower sideband to see what happened. I got output in excess of 125 W. to the dummy load in all cases. The cables to the wattmeter and dummy load are OK, the dummy load (switched to a Bird 8201) is OK. I took the lid off of the PA cage and placed an all purpose telescoping antenna next to the cage and ran the input into an HP spectrum analyzer. I got a very nice signal at 7.3 MHz and also very nice signals at 14, 21 and 28 MHz. There was no sign of any other oscillation of the finals. I did notice hash from the laptop computer switching power supply which went away when I unplugged it. Replacing and grounding the PA lid removed the extraneous harmonics at 14, 21 and 28 MHz. I also listened to the signal with another receiver and had a very clear sounding tone with no other noise up and down the dial. I varied the TR-4C VFO to make sure I was listening to the correct signal. I did measure the lead resistance of the Fluke leads. It is about 0.15 ohms, so the resistance of R45 will be about 2.25 ohms, closer to the nominal value. I don't think anything is wrong with the output circuitry. If there was, how could I be measuring power out to the dummy load? The wattmeter is a Swan 3000. I am not absolutely certain that it is working OK. I suppose I should try the light bulb technology that I used as a novice back when I knew it all. Now I have some reasonable equipment and don't know anything. Now, the last item puzzles me. I measured the ANT output to ground (SO-239) and it was 1.4 ohms, no way near 2.2 Megohms. RFC 7 goes to ground right at the SO-239. I would expect the DC resistance of the choke to be more than 1.4 ohms but less than 2.2 Megohms. Are we getting closer to an answer or just more confusion (I know it is the latter for me)? Awaiting further task assignments. I appreciate all the help. 73 Richard - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Thursday, July 14, 2011 10:27 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - OK. As others have said, we are missing something fundamental, as transmitters just do not do this!! :-) Verifying that the PA tubes ARE 6JB6 is a good idea. The Simpson is more than adequate for all but very low resistance readings, 2 - 15 ohm resistors and the voltage across them. You haven't confirmed which band you are using for test purposes. I suggest 40M. Are the PA plates showing any color that you have seen? Listen on another receiver and determine if you can hear the TR-4C on the frequency indicated by the dial reading. Once you find the signal, does it vary with PTO adjustment as expected? Since we have already measured the voltage across the three Cathode resistors and determined that they are approximately equal, nothing is gained by the risky (dangerous) measurement of 'plate' current. There is no place else for the current through R45 to come from other than the plate supply, so measuring the voltage across it is just as accurate and much less dangerous. Check your ohmmeter by shorting the test leads to determine if it reads 0.00 or if there is some lead resistance to be subtracted from the 2.4 ohm reading. 2.4 ohms is 20% high, but absolute current isn't critical at this point. I believe that we have determined that the meter IS measuring current correctly, the current just isn't behaving normally. It appears that 'something' is wrong with the output circuitry of the PA, preventing it from transferring power from the PA plates to the antenna, or the 'antenna' (dummy load) isn't accepting power. Measurement of the dummy load would be a good next step. If it measures near 50 ohms, then measure again at the transceiver end of the cable to verify that the cable is good. Measure the resistance of the ANT output jack on the radio, (power off, dummy load disconnected,) it should read about 2.2 Megohms to chassis. Rotate the PLATE and LOAD controls through their range with the ohmmeter connected, watching for anomalies
Re: [Drakelist] TR-4C Bias Adjustment
Garey, et al The PA tubes are Sylvania 6JB6, checked on a Hickok 600A and test good. I have seen no color to the plates of the finals. I have been doing all testing on 40 M. I came to suspect one of the sideband filters so I tried 80, 40 and 20 M., both upper and lower sideband to see what happened. I got output in excess of 125 W. to the dummy load in all cases. The cables to the wattmeter and dummy load are OK, the dummy load (switched to a Bird 8201) is OK. I took the lid off of the PA cage and placed an all purpose telescoping antenna next to the cage and ran the input into an HP spectrum analyzer. I got a very nice signal at 7.3 MHz and also very nice signals at 14, 21 and 28 MHz. There was no sign of any other oscillation of the finals. I did notice hash from the laptop computer switching power supply which went away when I unplugged it. Replacing and grounding the PA lid removed the extraneous harmonics at 14, 21 and 28 MHz. I also listened to the signal with another receiver and had a very clear sounding tone with no other noise up and down the dial. I varied the TR-4C VFO to make sure I was listening to the correct signal. I did measure the lead resistance of the Fluke leads. It is about 0.15 ohms, so the resistance of R45 will be about 2.25 ohms, closer to the nominal value. I don't think anything is wrong with the output circuitry. If there was, how could I be measuring power out to the dummy load? The wattmeter is a Swan 3000. I am not absolutely certain that it is working OK. I suppose I should try the light bulb technology that I used as a novice back when I knew it all. Now I have some reasonable equipment and don't know anything. Now, the last item puzzles me. I measured the ANT output to ground (SO-239) and it was 1.4 ohms, no way near 2.2 Megohms. RFC 7 goes to ground right at the SO-239. I would expect the DC resistance of the choke to be more than 1.4 ohms but less than 2.2 Megohms. Are we getting closer to an answer or just more confusion (I know it is the latter for me)? Awaiting further task assignments. I appreciate all the help. 73 Richard - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Thursday, July 14, 2011 10:27 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - OK. As others have said, we are missing something fundamental, as transmitters just do not do this!! :-) Verifying that the PA tubes ARE 6JB6 is a good idea. The Simpson is more than adequate for all but very low resistance readings, 2 - 15 ohm resistors and the voltage across them. You haven't confirmed which band you are using for test purposes. I suggest 40M. Are the PA plates showing any color that you have seen? Listen on another receiver and determine if you can hear the TR-4C on the frequency indicated by the dial reading. Once you find the signal, does it vary with PTO adjustment as expected? Since we have already measured the voltage across the three Cathode resistors and determined that they are approximately equal, nothing is gained by the risky (dangerous) measurement of 'plate' current. There is no place else for the current through R45 to come from other than the plate supply, so measuring the voltage across it is just as accurate and much less dangerous. Check your ohmmeter by shorting the test leads to determine if it reads 0.00 or if there is some lead resistance to be subtracted from the 2.4 ohm reading. 2.4 ohms is 20% high, but absolute current isn't critical at this point. I believe that we have determined that the meter IS measuring current correctly, the current just isn't behaving normally. It appears that 'something' is wrong with the output circuitry of the PA, preventing it from transferring power from the PA plates to the antenna, or the 'antenna' (dummy load) isn't accepting power. Measurement of the dummy load would be a good next step. If it measures near 50 ohms, then measure again at the transceiver end of the cable to verify that the cable is good. Measure the resistance of the ANT output jack on the radio, (power off, dummy load disconnected,) it should read about 2.2 Megohms to chassis. Rotate the PLATE and LOAD controls through their range with the ohmmeter connected, watching for anomalies. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Garey , Richard I, et al Since I am the student here, I can only be Richard II. I measured the resistance of R45, in circuit with the relay pulled. I'm not sure that made any difference. It measured 2.4 ohms on a Fluke 179. Since it is difficult to adjust for MAX or MIN on a DMM, I changed to a Simpson 260 (I know, maybe not too accurate). Then set SIDEBAND X, MODE X-CW cranked in some XMTR gain and tuned PLATE for MAX on the PLATE CURRENT meter (because tuning for MIN didn't work
Re: [Drakelist] TR-4C Bias Adjustment
Again...anywhere the plate current or its surrogate is measured, it MUST be capable of a dip. Especially if the load is anywhere near 50 ohms and the LOAD control is at minimum. Does the voltage over R45 dip to the 192mA value?? Also, if the meter is actually reading RF output, the sensitivity adjustment will change the reading--is this happening? Also, and I have not tried this, but if one puts an ohmeter across R45 and the meter switch has the meter in the circuit, one would see some action on the Drake meter from the ohmmeter test voltage. In most metering circuits, it is dangerous for the health of the meter movement to measure a shunt with an ohmmeter. Curt KU8L Garey Barrell wrote: See below. Donley wrote: Garey, et al The PA tubes are Sylvania 6JB6, checked on a Hickok 600A and test good. I have seen no color to the plates of the finals. OK. I have been doing all testing on 40 M. I came to suspect one of the sideband filters so I tried 80, 40 and 20 M., both upper and lower sideband to see what happened. I got output in excess of 125 W. to the dummy load in all cases. The cables to the wattmeter and dummy load are OK, the dummy load (switched to a Bird 8201) is OK. OK. Is this with the LOAD control at minimum? If you just peak TUNE and LOAD how much output do you see? I took the lid off of the PA cage and placed an all purpose telescoping antenna next to the cage and ran the input into an HP spectrum analyzer. I got a very nice signal at 7.3 MHz and also very nice signals at 14, 21 and 28 MHz. There was no sign of any other oscillation of the finals. I did notice hash from the laptop computer switching power supply which went away when I unplugged it. Replacing and grounding the PA lid removed the extraneous harmonics at 14, 21 and 28 MHz. I also listened to the signal with another receiver and had a very clear sounding tone with no other noise up and down the dial. I varied the TR-4C VFO to make sure I was listening to the correct signal. Cool. I didn't know you had access to 'real' equipment! :-) I did measure the lead resistance of the Fluke leads. It is about 0.15 ohms, so the resistance of R45 will be about 2.25 ohms, closer to the nominal value. OK I don't think anything is wrong with the output circuitry. If there was, how could I be measuring power out to the dummy load? The wattmeter is a Swan 3000. I am not absolutely certain that it is working OK. I suppose I should try the light bulb technology that I used as a novice back when I knew it all. Now I have some reasonable equipment and don't know anything. No I think you are getting output power, what you are seeing is commensurate with the actual measured cathode current. I think we're back to the meter circuit itself, which appears to be reading RF OUTPUT regardless of the switch position. The voltage you are seeing across R45 is correct , it's just NOT getting to the meter via the switch and/or R13. Trace that out and you'll have it. The high side of R45, to the 'front' contact of the switch, and with the switch slid 'forward' connecting the arm, with R13 and through R13 to the 'rear' contact of the switch and wire on to the positive terminal of the meter. Now, the last item puzzles me. I measured the ANT output to ground (SO-239) and it was 1.4 ohms, no way near 2.2 Megohms. RFC 7 goes to ground right at the SO-239. I would expect the DC resistance of the choke to be more than 1.4 ohms but less than 2.2 Megohms. Are we getting closer to an answer or just more confusion (I know it is the latter for me)? No, that's MY mistake. Certainly there is an RF choke directly across the antenna, as there has been for many years. It's a 'safety' choke so that if the plate blocking capacitor (C78) should fail shorted, placing 650 VDC on the _antenna_ there would be a blown fuse, or at worst a smoke signal from the RFC 7. It also serves to bleed off any accumulated buildup of static on the antenna from snow or nearby lightning strikes. Awaiting further task assignments. I appreciate all the help. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com 73 Richard - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Thursday, July 14, 2011 10:27 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - OK. As others have said, we are missing something fundamental, as transmitters just do not do this!! :-) Verifying that the PA tubes ARE 6JB6 is a good idea. The Simpson is more than adequate for all but very low resistance readings, 2 - 15 ohm resistors and the voltage across them. You haven't confirmed which band you are using for test purposes. I suggest 40M. Are the PA plates showing any color that you have seen? Listen on another receiver and determine if you can hear the TR-4C
Re: [Drakelist] TR-4C Bias Adjustment
- Original Message - From: Donley donley...@comcast.net To: k4...@mindspring.com; drakelist Drakelist@zerobeat.net Sent: Wednesday, July 13, 2011 7:29 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Garey , Richard I, et al Since I am the student here, I can only be Richard II. I measured the resistance of R45, in circuit with the relay pulled. I'm not sure that made any difference. It measured 2.4 ohms on a Fluke 179. Since it is difficult to adjust for MAX or MIN on a DMM, I changed to a Simpson 260 (I know, maybe not too accurate). Then set SIDEBAND X, MODE X-CW cranked in some XMTR gain and tuned PLATE for MAX on the PLATE CURRENT meter (because tuning for MIN didn't work). Max reading on the PLATE CURRENT meter again occurs about mid-range and falls off on both sides. The PLATE METER read 200 mA and the voltage on R45 was 0.46 VDC. Since R45 measured 2.4 ohms from before, the calculated current is about 192 mA. Close to the 200 mA on the PLATE METER. Then I tried tuning PLATE for MIN voltage on R45 with the Simpson. I could not tune to MIN, there was a MAX value about mid-range and it falls off on either side of MAX. The voltage on R45 was very close to 0.46 VDC, the same as above. Again, the calculated current was about 192 mA. Plate current or RF output? I checked the slide switch on the LOAD control. I took resistance measurements in each position and it seems to be working. I added a little DeOxit. I looked at the circuitry for RF output on the relay board ( I have most of Garey's Drake CD's). If the problem is in there, it is going to be a real pain to get to. I hope someone comes up with the Golden Screwdriver solution. When I was working, our solutions were Silver Bullets. Of course, that was before the price of silver skyrocketed. Richard II I guess that makes me Richard the Lionheart. The Simpson 260 is fine, these measurements do not need laboratory accuracy and I think continuous reading instruments are much better for this kind of measurement. There has to be some way of determining what the plate current is really doing. Since the Simpson has curent ranges it could be put in line with the plate supply line to the tubes. I think at the outside part of the feedthrough cap. I may have a downloaded schematic for this thing but have not looked at it so I don't know what the resistor designations are. At any rate, if you can measure the actual _plate_ current, rather than cathode current, as I think Garrey suggested, it would tell immediately if the meter is telling the truth. If it is there is something very strange going on. The symptoms are of the final tube oscillating. This is common on the high bands due to poor neutralization but should be rare at low frequencies because the coupling through the tube interelectrode capacitances will be lower. Nonetheless oscillation can take place. If you have access to a high frequency oscilloscope, or even better a spectrum analyser, you can see what is going out the antenna port. Operate the TX into the dummy load and use a sampling loop of a couple of turns to pick up some RF from the cage. Also, check up on the dummy load you are using if you have not already. Most of these loads are direct coupled to the connector so a resistance reading will show if the resistance of the load is way off or if its shorted or open. If its not really a resistor any more it could explain the problem. Also, do the tube plates show any color, if they do you probably have oscillation. Once it cured you will have to replace the tubes. I am grasping at straws here because transmitters just don't behave this way. Something is being missed. If the thing really is doing what the panel meter says I would also look at the coils and condensers of the final tuning circuit to make sure they are still doing what they are supposed to do. Begin with a _very_ thorough visual inspection. Disconnect the power supply while doing this. At the least the voltages in the final can give you a very nasty zap and at worst put you in the graveyard. Don't make the mistake of thinking that because this is relatively low power ham gear that it can't fry you as effectively as that thing at Sing Sing. Lets FIX this thing! -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Richard Knoppow wrote: - Original Message - From: Donley donley...@comcast.net To: k4...@mindspring.com; drakelist Drakelist@zerobeat.net Sent: Wednesday, July 13, 2011 7:29 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Garey , Richard I, et al Since I am the student here, I can only be Richard II. I measured the resistance of R45, in circuit with the relay pulled. I'm not sure that made any difference. It measured 2.4 ohms on a Fluke 179. Since it is difficult to adjust for MAX or MIN on a DMM, I changed to a Simpson 260 (I know, maybe not too accurate). Then set SIDEBAND X, MODE X-CW cranked in some XMTR gain and tuned PLATE for MAX on the PLATE CURRENT meter (because tuning for MIN didn't work). Max reading on the PLATE CURRENT meter again occurs about mid-range and falls off on both sides. The PLATE METER read 200 mA and the voltage on R45 was 0.46 VDC. Since R45 measured 2.4 ohms from before, the calculated current is about 192 mA. Close to the 200 mA on the PLATE METER. Then I tried tuning PLATE for MIN voltage on R45 with the Simpson. I could not tune to MIN, there was a MAX value about mid-range and it falls off on either side of MAX. The voltage on R45 was very close to 0.46 VDC, the same as above. Again, the calculated current was about 192 mA. Plate current or RF output? I checked the slide switch on the LOAD control. I took resistance measurements in each position and it seems to be working. I added a little DeOxit. I looked at the circuitry for RF output on the relay board ( I have most of Garey's Drake CD's). If the problem is in there, it is going to be a real pain to get to. I hope someone comes up with the Golden Screwdriver solution. When I was working, our solutions were Silver Bullets. Of course, that was before the price of silver skyrocketed. Richard II I guess that makes me Richard the Lionheart. The Simpson 260 is fine, these measurements do not need laboratory accuracy and I think continuous reading instruments are much better for this kind of measurement. There has to be some way of determining what the plate current is really doing. Since the Simpson has curent ranges it could be put in line with the plate supply line to the tubes. I think at the outside part of the feedthrough cap. I may have a downloaded schematic for this thing but have not looked at it so I don't know what the resistor designations are. At any rate, if you can measure the actual _plate_ current, rather than cathode current, as I think Garrey suggested, it would tell immediately if the meter is telling the truth. If it is there is something very strange going on. The symptoms are of the final tube oscillating. This is common on the high bands due to poor neutralization but should be rare at low frequencies because the coupling through the tube interelectrode capacitances will be lower. Nonetheless oscillation can take place. If you have access to a high frequency oscilloscope, or even better a spectrum analyser, you can see what is going out the antenna port. Operate the TX into the dummy load and use a sampling loop of a couple of turns to pick up some RF from the cage. Also, check up on the dummy load you are using if you have not already. Most of these loads are direct coupled to the connector so a resistance reading will show if the resistance of the load is way off or if its shorted or open. If its not really a resistor any more it could explain the problem. Also, do the tube plates show any color, if they do you probably have oscillation. Once it cured you will have to replace the tubes. I am grasping at straws here because transmitters just don't behave this way. Something is being missed. If the thing really is doing what the panel meter says I would also look at the coils and condensers of the final tuning circuit to make sure they are still doing what they are supposed to do. Begin with a _very_ thorough visual inspection. Disconnect the power supply while doing this. At the least the voltages in the final can give you a very nasty zap and at worst put you in the graveyard. Don't make the mistake of thinking that because this is relatively low power ham gear that it can't fry you as effectively as that thing at Sing Sing. Lets FIX this thing! -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist GM All: Richard has described it well by saying that PA don't act this way. My feeling is something is being missed that is fundamental. 1. If you can't get the plate current to dip, that isn't a metering problem. I mean the REAL final plate current or its surrogate, cathode current. Forget R45measure the plate current as Richard suggested by putting an ammeter in series with the plate line (danger) or by looking at the voltage over the cathode resistor(s). You can use just one
Re: [Drakelist] TR-4C Bias Adjustment
Richard II, Begin with a quick check to eliminate one variable. Verify the tubes are indeed 6JB6. I once managed to causeoscillation at 40 with 12GJ5's in a TR-3. Kihwal, K9SUL - Original Message - From: Richard Knoppow 1oldle...@ix.netcom.com To: Donley donley...@comcast.net; k4...@mindspring.com; drakelist Drakelist@zerobeat.net Cc: Sent: Thursday, July 14, 2011 2:24 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment - Original Message - From: Donley donley...@comcast.net To: k4...@mindspring.com; drakelist Drakelist@zerobeat.net Sent: Wednesday, July 13, 2011 7:29 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Garey , Richard I, et al Since I am the student here, I can only be Richard II. I measured the resistance of R45, in circuit with the relay pulled. I'm not sure that made any difference. It measured 2.4 ohms on a Fluke 179. Since it is difficult to adjust for MAX or MIN on a DMM, I changed to a Simpson 260 (I know, maybe not too accurate). Then set SIDEBAND X, MODE X-CW cranked in some XMTR gain and tuned PLATE for MAX on the PLATE CURRENT meter (because tuning for MIN didn't work). Max reading on the PLATE CURRENT meter again occurs about mid-range and falls off on both sides. The PLATE METER read 200 mA and the voltage on R45 was 0.46 VDC. Since R45 measured 2.4 ohms from before, the calculated current is about 192 mA. Close to the 200 mA on the PLATE METER. Then I tried tuning PLATE for MIN voltage on R45 with the Simpson. I could not tune to MIN, there was a MAX value about mid-range and it falls off on either side of MAX. The voltage on R45 was very close to 0.46 VDC, the same as above. Again, the calculated current was about 192 mA. Plate current or RF output? I checked the slide switch on the LOAD control. I took resistance measurements in each position and it seems to be working. I added a little DeOxit. I looked at the circuitry for RF output on the relay board ( I have most of Garey's Drake CD's). If the problem is in there, it is going to be a real pain to get to. I hope someone comes up with the Golden Screwdriver solution. When I was working, our solutions were Silver Bullets. Of course, that was before the price of silver skyrocketed. Richard II I guess that makes me Richard the Lionheart. The Simpson 260 is fine, these measurements do not need laboratory accuracy and I think continuous reading instruments are much better for this kind of measurement. There has to be some way of determining what the plate current is really doing. Since the Simpson has curent ranges it could be put in line with the plate supply line to the tubes. I think at the outside part of the feedthrough cap. I may have a downloaded schematic for this thing but have not looked at it so I don't know what the resistor designations are. At any rate, if you can measure the actual _plate_ current, rather than cathode current, as I think Garrey suggested, it would tell immediately if the meter is telling the truth. If it is there is something very strange going on. The symptoms are of the final tube oscillating. This is common on the high bands due to poor neutralization but should be rare at low frequencies because the coupling through the tube interelectrode capacitances will be lower. Nonetheless oscillation can take place. If you have access to a high frequency oscilloscope, or even better a spectrum analyser, you can see what is going out the antenna port. Operate the TX into the dummy load and use a sampling loop of a couple of turns to pick up some RF from the cage. Also, check up on the dummy load you are using if you have not already. Most of these loads are direct coupled to the connector so a resistance reading will show if the resistance of the load is way off or if its shorted or open. If its not really a resistor any more it could explain the problem. Also, do the tube plates show any color, if they do you probably have oscillation. Once it cured you will have to replace the tubes. I am grasping at straws here because transmitters just don't behave this way. Something is being missed. If the thing really is doing what the panel meter says I would also look at the coils and condensers of the final tuning circuit to make sure they are still doing what they are supposed to do. Begin with a _very_ thorough visual inspection. Disconnect the power supply while doing this. At the least the voltages in the final can give you a very nasty zap and at worst put you in the graveyard. Don't make the mistake of thinking that because this is relatively low power ham gear that it can't fry you as effectively as that thing at Sing Sing. Lets FIX this thing! -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Richard - OK. As others have said, we are missing something fundamental, as transmitters just do not do this!! :-) Verifying that the PA tubes ARE 6JB6 is a good idea. The Simpson is more than adequate for all but very low resistance readings, 2 - 15 ohm resistors and the voltage across them. You haven't confirmed which band you are using for test purposes. I suggest 40M. Are the PA plates showing any color that you have seen? Listen on another receiver and determine if you can hear the TR-4C on the frequency indicated by the dial reading. Once you find the signal, does it vary with PTO adjustment as expected? Since we have already measured the voltage across the three Cathode resistors and determined that they are approximately equal, nothing is gained by the risky (dangerous) measurement of 'plate' current. There is no place else for the current through R45 to come from other than the plate supply, so measuring the voltage across it is just as accurate and much less dangerous. Check your ohmmeter by shorting the test leads to determine if it reads 0.00 or if there is some lead resistance to be subtracted from the 2.4 ohm reading. 2.4 ohms is 20% high, but absolute current isn't critical at this point. I believe that we have determined that the meter IS measuring current correctly, the current just isn't behaving normally. It appears that 'something' is wrong with the output circuitry of the PA, preventing it from transferring power from the PA plates to the antenna, or the 'antenna' (dummy load) isn't accepting power. Measurement of the dummy load would be a good next step. If it measures near 50 ohms, then measure again at the transceiver end of the cable to verify that the cable is good. Measure the resistance of the ANT output jack on the radio, (power off, dummy load disconnected,) it should read about 2.2 Megohms to chassis. Rotate the PLATE and LOAD controls through their range with the ohmmeter connected, watching for anomalies. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Garey , Richard I, et al Since I am the student here, I can only be Richard II. I measured the resistance of R45, in circuit with the relay pulled. I'm not sure that made any difference. It measured 2.4 ohms on a Fluke 179. Since it is difficult to adjust for MAX or MIN on a DMM, I changed to a Simpson 260 (I know, maybe not too accurate). Then set SIDEBAND X, MODE X-CW cranked in some XMTR gain and tuned PLATE for MAX on the PLATE CURRENT meter (because tuning for MIN didn't work). Max reading on the PLATE CURRENT meter again occurs about mid-range and falls off on both sides. The PLATE METER read 200 mA and the voltage on R45 was 0.46 VDC. Since R45 measured 2.4 ohms from before, the calculated current is about 192 mA. Close to the 200 mA on the PLATE METER. Then I tried tuning PLATE for MIN voltage on R45 with the Simpson. I could not tune to MIN, there was a MAX value about mid-range and it falls off on either side of MAX. The voltage on R45 was very close to 0.46 VDC, the same as above. Again, the calculated current was about 192 mA. Plate current or RF output? I checked the slide switch on the LOAD control. I took resistance measurements in each position and it seems to be working. I added a little DeOxit. I looked at the circuitry for RF output on the relay board ( I have most of Garey's Drake CD's). If the problem is in there, it is going to be a real pain to get to. I hope someone comes up with the Golden Screwdriver solution. When I was working, our solutions were Silver Bullets. Of course, that was before the price of silver skyrocketed. Richard II - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Wednesday, July 13, 2011 1:42 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard Knoppow wrote: - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Wednesday, July 13, 2011 6:19 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I don't recall a C73 reference.? Possibly C74, which is the Cathode lead feedthrough? Rats, I thought we might be on to something. The fact that the meter reading peak results in The other Richard I think. C-73 was my blunder from looking at the TR-4 schematics. Obviously the TR-4C has considerable differences. I meant to find a point where the collective voltage drop across the cathode resistors could be measured independandly of the panel meter. My idea was not to get a precise reading but only to see if the current there behaved normally, i.e., dipped at reasonance. The peaking of of the meter when adjusting plate tuning sure suggests its looking at output not plate current. Maybe not a bad switch but it could be something in the wiring there. At any rate an RF
Re: [Drakelist] TR-4C Bias Adjustment
Richard - I hate losing all our previous information on this message... My fault. Just keep the other one. Adjusting the BIAS control while measuring the voltage across each of the Cathode resistors is ok, but you also need to measure the resistors, preferably with a DMM. Even one ohm either side of 15 on one or more resistors (likely, often more) can throw you off. I don't recall a C73 reference.? Possibly C74, which is the Cathode lead feedthrough? Rats, I thought we might be on to something. The fact that the meter reading peak results in maximum RF OUTPUT sure sounds like the OUTPUT function of the PLATE meter. Measure R45 with your DMM. Should be 2 ohms, but measure as accurately as you can. Then measure the voltage across R45 while adjusting the PLATE control. This voltage should _dip_ (minimize) coincidentally with maximum RF OUTPUT. Calculate PLATE current using measured voltage and resistance of R45. If this is normal, then we have confirmed that we don't have an oscillation as Al suggested yesterday, and the problem is strictly with the meter circuit. The meter circuit is very simple, just confusing the way it's drawn. To measure PLATE current, R45 is in series with the Cathodes of the PA tubes, and the meter, with R13 (up on the LOAD control shaft switch) in series, measures the VOLTAGE across R45. To measure RF OUTPUT, a voltage divider of C161 and C162 samples the RF OUTPUT, which is then rectified by D9, integrated in C163 and the resultant positive voltage is applied directly to the meter. Slide switches are pretty simple, and not prone to shorting. Check the wiring around the switch to ensure that there aren't any shorts, and ensure that the switch slider is actually being moved by the LOAD control shaft. It certainly appears that the meter is reading RF OUTPUT rather than PLATE current, and this can be confirmed by the R45 measurements above. What band are you testing on?? I normally troubleshoot on 40M. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Completed tasks. Adjusted bias control until 0.5 VDC across cathode resistor, equals 33 mA, three resistors in parallel equals 100 mA total bias current. Bias voltage is -55 VDC at this point. No bias current measurement on plate current meter (actually has been just a slight wiggle all along, but nothing more than a half pointer width wiggle). C-73 is not a feedthrough, what point should be measured? The LOAD control spring is intact and functioning. In tune procedure, PLATE control does not dip, it is maximum about mid-range and reduces to near zero on either side of peak. LOAD control pushed in or out, peak occurs about mid-range and falls off on either side of peak. Is this pointing to the RF output slide switch circuit, possibly a shorted switch? - Original Message - From: Richard Knoppow 1oldle...@ix.netcom.com To: k4...@mindspring.com; drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 10:26 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 6:36 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - This is what I referred to in my last message. There is no adjusting pot on the TR-4C, but the meter is switched from Plate current to output meter. That's why I said to push and pull the LOAD control a couple of times. There should be a hairpin shaped spring on the LOAD control shaft that pushes the LOAD knob OUT for PLATE current reading and you PUSH it IN for RF OUTPUT reading. 73, Garey - K4OAH Glen Allen, VA That's obviously a differenc I missed between the TR-4 and TR-4C but the idea is the same. If the meter is stuck reading output it could behave as described. That's why I suggested an independant measurement of cathode current. If he gets a dip there but not on the meter the switch is probably no good or something else is causing the meter to read output all the time. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
I have had two separate issues with this switch. Deoxit and working back and forth a few times solved it. 73 Mark N5KAE___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Donley wrote: Completed tasks. Adjusted bias control until 0.5 VDC across cathode resistor, equals 33 mA, three resistors in parallel equals 100 mA total bias current. Bias voltage is -55 VDC at this point. No bias current measurement on plate current meter (actually has been just a slight wiggle all along, but nothing more than a half pointer width wiggle). C-73 is not a feedthrough, what point should be measured? The LOAD control spring is intact and functioning. In tune procedure, PLATE control does not dip, it is maximum about mid-range and reduces to near zero on either side of peak. LOAD control pushed in or out, peak occurs about mid-range and falls off on either side of peak. Is this pointing to the RF output slide switch circuit, possibly a shorted switch? - Original Message - From: Richard Knoppow 1oldle...@ix.netcom.com To: k4...@mindspring.com; drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 10:26 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 6:36 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - This is what I referred to in my last message. There is no adjusting pot on the TR-4C, but the meter is switched from Plate current to output meter. That's why I said to push and pull the LOAD control a couple of times. There should be a hairpin shaped spring on the LOAD control shaft that pushes the LOAD knob OUT for PLATE current reading and you PUSH it IN for RF OUTPUT reading. 73, Garey - K4OAH Glen Allen, VA That's obviously a differenc I missed between the TR-4 and TR-4C but the idea is the same. If the meter is stuck reading output it could behave as described. That's why I suggested an independant measurement of cathode current. If he gets a dip there but not on the meter the switch is probably no good or something else is causing the meter to read output all the time. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist At the risk of being redundant or stupid, I'll jump in here and say that while in tune and the plate meter is behaving as you describe (peak and then low either side of that) the meter is more than likely stuck in the RF output mode (load switch not switching as others have pointed out) It would take a pretty messed up system to make the actual plate current respond to tuning they way you describe. If you watch the cathode resistor voltage while tuning, same as while you adjusted for 33mA, I bet you will see a pronounced dip at the point of the peak you see on the meter. Curt KU8L ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
- Original Message - From: Curt Nixon cptc...@flash.net To: Donley donley...@comcast.net Cc: Richard Knoppow 1oldle...@ix.netcom.com; k4...@mindspring.com; drakelist Drakelist@zerobeat.net Sent: Wednesday, July 13, 2011 9:43 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment At the risk of being redundant or stupid, I'll jump in here and say that while in tune and the plate meter is behaving as you describe (peak and then low either side of that) the meter is more than likely stuck in the RF output mode (load switch not switching as others have pointed out) It would take a pretty messed up system to make the actual plate current respond to tuning they way you describe. If you watch the cathode resistor voltage while tuning, same as while you adjusted for 33mA, I bet you will see a pronounced dip at the point of the peak you see on the meter. Curt KU8L Thank you Curt, that is a much clearer statement of what I was trying to say. C-73 is a mistake, its the part designation for the TR-4, not the TR-4C. The idea was to find a suitable place to measure the same thing as the front panel meter is _supposed_ to be seeing with an external meter. The exact value of the voltage is not important only that is dip at plate resonance. If it does it confirms that there is a problem with the meter switching or wiring. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Curt Nixon wrote: Donley wrote: Completed tasks. Adjusted bias control until 0.5 VDC across cathode resistor, equals 33 mA, three resistors in parallel equals 100 mA total bias current. Bias voltage is -55 VDC at this point. No bias current measurement on plate current meter (actually has been just a slight wiggle all along, but nothing more than a half pointer width wiggle). C-73 is not a feedthrough, what point should be measured? The LOAD control spring is intact and functioning. In tune procedure, PLATE control does not dip, it is maximum about mid-range and reduces to near zero on either side of peak. LOAD control pushed in or out, peak occurs about mid-range and falls off on either side of peak. Is this pointing to the RF output slide switch circuit, possibly a shorted switch? - Original Message - From: Richard Knoppow 1oldle...@ix.netcom.com To: k4...@mindspring.com; drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 10:26 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 6:36 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - This is what I referred to in my last message. There is no adjusting pot on the TR-4C, but the meter is switched from Plate current to output meter. That's why I said to push and pull the LOAD control a couple of times. There should be a hairpin shaped spring on the LOAD control shaft that pushes the LOAD knob OUT for PLATE current reading and you PUSH it IN for RF OUTPUT reading. 73, Garey - K4OAH Glen Allen, VA That's obviously a differenc I missed between the TR-4 and TR-4C but the idea is the same. If the meter is stuck reading output it could behave as described. That's why I suggested an independant measurement of cathode current. If he gets a dip there but not on the meter the switch is probably no good or something else is causing the meter to read output all the time. At the risk of being redundant or stupid, I'll jump in here and say that while in tune and the plate meter is behaving as you describe (peak and then low either side of that) the meter is more than likely stuck in the RF output mode (load switch not switching as others have pointed out) It would take a pretty messed up system to make the actual plate current respond to tuning they way you describe. If you watch the cathode resistor voltage while tuning, same as while you adjusted for 33mA, I bet you will see a pronounced dip at the point of the peak you see on the meter. Curt KU8L Curt - Generally speaking, you are correct. My last message suggested measuring actual PLATE current with a separate meter to confirm our suspicion that the internal meter is in fact measuring output power rather than cathode current. However, this type of behavior, 'PLATE' meter peaking coinciding with maximum RF output is in the case of an oscillating PA. This is most often the result of either weird, off-brand PA tubes, or misadjusted neutralization. Based on what we have eliminated so far, it's looking more and more like a metering problem. Unfortunately, we have already established that the transceiver has NEVER worked for its present owner!! Richard is tasked with checking and verifying the meter switching involved per my last message. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Mark - Yes, they do develop oxidized contacts. However in this case that type of failure would not present as being 'stuck' in one position. When Richard checks the items in my last message we'll have a pretty good idea what's happening! Thanks for contributing! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Mark Nace wrote: I have had two separate issues with this switch. Deoxit and working back and forth a few times solved it. 73 Mark N5KAE *From: * Garey Barrell k4...@mindspring.com; *To: * drakelist Drakelist@zerobeat.net; *Subject: * Re: [Drakelist] TR-4C Bias Adjustment *Sent: * Wed, Jul 13, 2011 1:19:27 PM Richard - I hate losing all our previous information on this message... My fault. Just keep the other one. Adjusting the BIAS control while measuring the voltage across each of the Cathode resistors is ok, but you also need to measure the resistors, preferably with a DMM. Even one ohm either side of 15 on one or more resistors (likely, often more) can throw you off. I don't recall a C73 reference.? Possibly C74, which is the Cathode lead feedthrough? Rats, I thought we might be on to something. The fact that the meter reading peak results in maximum RF OUTPUT sure sounds like the OUTPUT function of the PLATE meter. Measure R45 with your DMM. Should be 2 ohms, but measure as accurately as you can. Then measure the voltage across R45 while adjusting the PLATE control. This voltage should _dip_ (minimize) coincidentally with maximum RF OUTPUT. Calculate PLATE current using measured voltage and resistance of R45. If this is normal, then we have confirmed that we don't have an oscillation as Al suggested yesterday, and the problem is strictly with the meter circuit. The meter circuit is very simple, just confusing the way it's drawn. To measure PLATE current, R45 is in series with the Cathodes of the PA tubes, and the meter, with R13 (up on the LOAD control shaft switch) in series, measures the VOLTAGE across R45. To measure RF OUTPUT, a voltage divider of C161 and C162 samples the RF OUTPUT, which is then rectified by D9, integrated in C163 and the resultant positive voltage is applied directly to the meter. Slide switches are pretty simple, and not prone to shorting. Check the wiring around the switch to ensure that there aren't any shorts, and ensure that the switch slider is actually being moved by the LOAD control shaft. It certainly appears that the meter is reading RF OUTPUT rather than PLATE current, and this can be confirmed by the R45 measurements above. What band are you testing on?? I normally troubleshoot on 40M. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Completed tasks. Adjusted bias control until 0.5 VDC across cathode resistor, equals 33 mA, three resistors in parallel equals 100 mA total bias current. Bias voltage is -55 VDC at this point. No bias current measurement on plate current meter (actually has been just a slight wiggle all along, but nothing more than a half pointer width wiggle). C-73 is not a feedthrough, what point should be measured? The LOAD control spring is intact and functioning. In tune procedure, PLATE control does not dip, it is maximum about mid-range and reduces to near zero on either side of peak. LOAD control pushed in or out, peak occurs about mid-range and falls off on either side of peak. Is this pointing to the RF output slide switch circuit, possibly a shorted switch? - Original Message - From: Richard Knoppow 1oldle...@ix.netcom.com javascript:return To: k4...@mindspring.com javascript:return; drakelist Drakelist@zerobeat.net javascript:return Sent: Tuesday, July 12, 2011 10:26 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment - Original Message - From: Garey Barrell k4...@mindspring.com javascript:return To: drakelist Drakelist@zerobeat.net javascript:return Sent: Tuesday, July 12, 2011 6:36 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - This is what I referred to in my last message. There is no adjusting pot on the TR-4C, but the meter is switched from Plate current to output meter. That's why I said to push and pull the LOAD control a couple of times. There should be a hairpin shaped spring on the LOAD control shaft that pushes the LOAD knob OUT for PLATE current reading and you PUSH it IN for RF OUTPUT reading. 73, Garey - K4OAH Glen Allen, VA That's obviously a differenc I missed between the TR-4 and TR-4C but the idea is the same. If the meter is stuck reading output it could behave as described. That's why I suggested an independant measurement of cathode current. If he gets a dip there but not on the meter the switch is probably
Re: [Drakelist] TR-4C Bias Adjustment
Richard Knoppow wrote: - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Wednesday, July 13, 2011 6:19 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I don't recall a C73 reference.? Possibly C74, which is the Cathode lead feedthrough? Rats, I thought we might be on to something. The fact that the meter reading peak results in The other Richard I think. C-73 was my blunder from looking at the TR-4 schematics. Obviously the TR-4C has considerable differences. I meant to find a point where the collective voltage drop across the cathode resistors could be measured independandly of the panel meter. My idea was not to get a precise reading but only to see if the current there behaved normally, i.e., dipped at reasonance. The peaking of of the meter when adjusting plate tuning sure suggests its looking at output not plate current. Maybe not a bad switch but it could be something in the wiring there. At any rate an RF amplifier just can't behave the way the meter says its doing. I have enountered bad slide switches but not many, it can't be discounted with something as mysterious as this. It could be something as simple as a solder butch or something having been mis-wired in the past. The idea is to isolate the problem and I think using an independant meter would help. There has been a lot of tail-chasing over this problem and I am afraid I made it worse by making a fundamental mistake, that is making an assumption, in this case that the two versions of the TR-4 were mostly similar. My only excuse is that I am on a medication for the after effects of Shingles that makes me a little dumber even than usual. Richard - Unfortunately, I don't have medication as an excuse! I did have low blood pressure after rehab this morning, does that count?!? :-) C74 would be a reasonable place to measure the drop across R45 to check for a dip coinciding with maximum output. I was trying to set the BIAS voltage correctly by measuring across the Cathode resistors, and the resistor's values, 'accurately'. Richard came up with ~ -50 VDC, which I'm afraid could result in over-dissipation of the PA, -60 to -65 is more typical for 100 mA. THIS RF amplifier _MAY_ behave just as described, (max output and max current coinciding,) with 'some' PA tubes and/or improperly adjusted neutralization, by oscillating on its own. Yet another problem is that this transceiver has NEVER worked for this owner, so a 'golden screwdriver' may yet turn out to be the problem!! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Garey Barrell wrote: Richard Knoppow wrote: - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Wednesday, July 13, 2011 6:19 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I don't recall a C73 reference.? Possibly C74, which is the Cathode lead feedthrough? Rats, I thought we might be on to something. The fact that the meter reading peak results in The other Richard I think. C-73 was my blunder from looking at the TR-4 schematics. Obviously the TR-4C has considerable differences. I meant to find a point where the collective voltage drop across the cathode resistors could be measured independandly of the panel meter. My idea was not to get a precise reading but only to see if the current there behaved normally, i.e., dipped at reasonance. The peaking of of the meter when adjusting plate tuning sure suggests its looking at output not plate current. Maybe not a bad switch but it could be something in the wiring there. At any rate an RF amplifier just can't behave the way the meter says its doing. I have enountered bad slide switches but not many, it can't be discounted with something as mysterious as this. It could be something as simple as a solder butch or something having been mis-wired in the past. The idea is to isolate the problem and I think using an independant meter would help. There has been a lot of tail-chasing over this problem and I am afraid I made it worse by making a fundamental mistake, that is making an assumption, in this case that the two versions of the TR-4 were mostly similar. My only excuse is that I am on a medication for the after effects of Shingles that makes me a little dumber even than usual. Richard - Unfortunately, I don't have medication as an excuse! I did have low blood pressure after rehab this morning, does that count?!? :-) C74 would be a reasonable place to measure the drop across R45 to check for a dip coinciding with maximum output. I was trying to set the BIAS voltage correctly by measuring across the Cathode resistors, and the resistor's values, 'accurately'. Richard came up with ~ -50 VDC, which I'm afraid could result in over-dissipation of the PA, -60 to -65 is more typical for 100 mA. THIS RF amplifier _MAY_ behave just as described, (max output and max current coinciding,) with 'some' PA tubes and/or improperly adjusted neutralization, by oscillating on its own. Yet another problem is that this transceiver has NEVER worked for this owner, so a 'golden screwdriver' may yet turn out to be the problem!! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist Yes..the whole PA going into oscillation could do that as you described although I've never seen a Drake PA do that on 40M or below. It would also be weird if it was oscillating on tune and also had near zero bias current at idle. I have seen badly oxidized meter switch contacts but they always seem to just mess up the RF out mode, not the PA current. Anyway..sounds like the right track. PS...make sure it is the PLATE control for the dip and not the the LOAD control during tune-up. Getting this in reverse will really skew the result! :) Curt KU8L ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Garey , Richard I, et al Since I am the student here, I can only be Richard II. I measured the resistance of R45, in circuit with the relay pulled. I'm not sure that made any difference. It measured 2.4 ohms on a Fluke 179. Since it is difficult to adjust for MAX or MIN on a DMM, I changed to a Simpson 260 (I know, maybe not too accurate). Then set SIDEBAND X, MODE X-CW cranked in some XMTR gain and tuned PLATE for MAX on the PLATE CURRENT meter (because tuning for MIN didn't work). Max reading on the PLATE CURRENT meter again occurs about mid-range and falls off on both sides. The PLATE METER read 200 mA and the voltage on R45 was 0.46 VDC. Since R45 measured 2.4 ohms from before, the calculated current is about 192 mA. Close to the 200 mA on the PLATE METER. Then I tried tuning PLATE for MIN voltage on R45 with the Simpson. I could not tune to MIN, there was a MAX value about mid-range and it falls off on either side of MAX. The voltage on R45 was very close to 0.46 VDC, the same as above. Again, the calculated current was about 192 mA. Plate current or RF output? I checked the slide switch on the LOAD control. I took resistance measurements in each position and it seems to be working. I added a little DeOxit. I looked at the circuitry for RF output on the relay board ( I have most of Garey's Drake CD's). If the problem is in there, it is going to be a real pain to get to. I hope someone comes up with the Golden Screwdriver solution. When I was working, our solutions were Silver Bullets. Of course, that was before the price of silver skyrocketed. Richard II - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Wednesday, July 13, 2011 1:42 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard Knoppow wrote: - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Wednesday, July 13, 2011 6:19 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I don't recall a C73 reference.? Possibly C74, which is the Cathode lead feedthrough? Rats, I thought we might be on to something. The fact that the meter reading peak results in The other Richard I think. C-73 was my blunder from looking at the TR-4 schematics. Obviously the TR-4C has considerable differences. I meant to find a point where the collective voltage drop across the cathode resistors could be measured independandly of the panel meter. My idea was not to get a precise reading but only to see if the current there behaved normally, i.e., dipped at reasonance. The peaking of of the meter when adjusting plate tuning sure suggests its looking at output not plate current. Maybe not a bad switch but it could be something in the wiring there. At any rate an RF amplifier just can't behave the way the meter says its doing. I have enountered bad slide switches but not many, it can't be discounted with something as mysterious as this. It could be something as simple as a solder butch or something having been mis-wired in the past. The idea is to isolate the problem and I think using an independant meter would help. There has been a lot of tail-chasing over this problem and I am afraid I made it worse by making a fundamental mistake, that is making an assumption, in this case that the two versions of the TR-4 were mostly similar. My only excuse is that I am on a medication for the after effects of Shingles that makes me a little dumber even than usual. Richard - Unfortunately, I don't have medication as an excuse! I did have low blood pressure after rehab this morning, does that count?!? :-) C74 would be a reasonable place to measure the drop across R45 to check for a dip coinciding with maximum output. I was trying to set the BIAS voltage correctly by measuring across the Cathode resistors, and the resistor's values, 'accurately'. Richard came up with ~ -50 VDC, which I'm afraid could result in over-dissipation of the PA, -60 to -65 is more typical for 100 mA. THIS RF amplifier _MAY_ behave just as described, (max output and max current coinciding,) with 'some' PA tubes and/or improperly adjusted neutralization, by oscillating on its own. Yet another problem is that this transceiver has NEVER worked for this owner, so a 'golden screwdriver' may yet turn out to be the problem!! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Garey, Sorry about the delay in my response. Time gets away from me. I acquired the TR-4C several years ago and my normal procedure is to put a new acquisition on the bench and run it through a simple use test. Then I tag it with the information, working or not, and put it on the shelf for later free time. This one has no tag, so my procedure must have failed. I don't remember if the bias worked or not. My guess is not. Yes, the receiver works just fine. The RV-4C is on the shelf, not connected. VOX and ANTI-VOX are set at mid-range. The transmitter works fine also, I just can't measure the bias current. Can I assume that the bias current is close to 100 mA if the bias voltage is ~ -60 VDC? It seems like there must be an open in the meter circuit when switched to set the bias. That should involve switches and relay contacts in the circuit. I am not very good at tracing circuits on the schematic when they start running through switches. In SSB mode, NON-X position, grounding the 'TIP' MIC connector pulls in the relay. I should probably order a new relay and try it, but the old one appeared to work when I had it out and open for cleaning. One set of contacts was somewhat dirty but I had good continuity after cleaning. Richard Richard - Probably should have asked this question a while ago, but has this transmitter EVER worked, to your knowledge? Does the receiver work?? Do you have an RV-4(C) connected? Verify that the VOX and ANTI-VOX controls on the right side are about mid-range. Unless something has been rewired, the Cathode line of the PA should read that 0.3 to 0.4 VDC ANY time the relay (the four pole one near the power connector) is energized, regardless of ANY other switch position. The Cathode lead comes through the feedthrough cap on the PA section shield, goes to R45 (2 ohms, on the board with the relay) and is hard wired from the other end of R45 to the relay contact. This contact is grounded any time the relay is energized, grounding the PA Cathodes. When it's in SSB, in the NON-X position, try grounding the 'TIP' of the MIC connector and see if the relay pulls in. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Garey, I replaced the 6EV7 and there was no change. The plate voltage on the 6EV7 measures a little low at 230 VDC (supposed to 260). This makes the voltage on the relay lower than the 48 VDC (measures about 26 V if I remember correctly, but it seems to pull in okay). I measured the four voltages in all combinations of the sideband switch and the mode switch settings (sideband switch in non-X position and mode switch in SSB position and then in X-CW position). Then (sideband switch in X position and mode switch in SSB position and then X-CW position). The four plate voltage measurements were 687 to 690 VDC. The four screen voltage measurements were 230 to 236 VDC (a little low if 260 is correct). The four grid voltage measurements were around -60 VDC. When the Mode switch was in the SSB position, the cathode voltage was 156 VDC for each position of the sideband switch. When the Mode switch was in the X-CW position, the cathode voltage was 0.3 to 0.4 VDC. When I said I could adjust the bias voltage in the sideband X position, I didn't tell you that to do that I had to advance the transmitter gain control slightly to get 100 mA. But when I switched back to sideband non-X position, the current dropped to zero with no control by the bias knob on the AC-4. I have pulled the one relay and opened it and cleaned the contacts with no change. Also cleaned the contacts on the second relay. I have a power supply rebuild kit to install but the voltages appear to be okay and steady. I should probably order a new relay and try that. If I adjust the bias pot to get -60 VDC, I have no idea what the bias current is, but I get plenty of power out, around 200 watts, so it seems to work , I just can't measure the current. ?? Richard - Original Message - From: Garey Barrell k4...@mindspring.com To: Donley donley...@comcast.net Cc: Drakelist Drakelist@zerobeat.net Sent: Saturday, July 09, 2011 3:00 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I've thought about this some more this afternoon, and I think the next step is to measure the PA voltages with the switches set per the manual and see WHAT is missing. There aren't that many choices, ONE or more of the three are missing or incorrect. Plate +650 VDC Screen + 260 VDC Grid ~ -60 VDC Cathode ~ 0 VDC 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: My guess is that either a KEY is plugged in and open, or the 'shorting' jack, isn't! Try just inserting a phone plug into the KEY jack several times to see if that shorting contact will close as it should. Otherwise just
Re: [Drakelist] TR-4C Bias Adjustment
by the bias knob on the AC-4. I have pulled the one relay and opened it and cleaned the contacts with no change. Also cleaned the contacts on the second relay. I have a power supply rebuild kit to install but the voltages appear to be okay and steady. I should probably order a new relay and try that. If I adjust the bias pot to get -60 VDC, I have no idea what the bias current is, but I get plenty of power out, around 200 watts, so it seems to work , I just can't measure the current. ?? Richard - Original Message - From: Garey Barrell k4...@mindspring.com To: Donley donley...@comcast.net Cc: Drakelist Drakelist@zerobeat.net Sent: Saturday, July 09, 2011 3:00 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I've thought about this some more this afternoon, and I think the next step is to measure the PA voltages with the switches set per the manual and see WHAT is missing. There aren't that many choices, ONE or more of the three are missing or incorrect. Plate +650 VDC Screen + 260 VDC Grid ~ -60 VDC Cathode ~ 0 VDC 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: My guess is that either a KEY is plugged in and open, or the 'shorting' jack, isn't! Try just inserting a phone plug into the KEY jack several times to see if that shorting contact will close as it should. Otherwise just insert a shorted phone plug into the KEY jack. Garey, Been there, did that. The key is not plugged in but the jack is shorted as it should be. When set up according to the manual, there is no bias current indicated on the meter when adjusting the bias control, but there is adjustable voltage (around -60 VDC +/- adjustable) on the PA grids. If I switch the sideband back to the X position, there is current indicated and I can easily vary it with the bias control and get 100 mA. What is the difference in being in the X sideband or opposite sideband position? Both are done with no transmitter gain and I get current in the X position and not in the other. Maybe there is an open condition on the sideband switch when it is in the non X position. Question - Is the bias current just plate current with no transmitter gain? Thanks. Richard kc9ub - Original Message - From: Garey Barrell k4...@mindspring.com To: Donley donley...@comcast.net Cc: Drakelist Drakelist@zerobeat.net Sent: Friday, July 08, 2011 11:18 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I'm not sure I follow your description below. 1. There is only ONE metering circuit, NO switching involved. If it can read PLATE current it can also read BIAS current. 2. 26 V across the relay sounds low, but if it pulls in that can be left til later. The manual says to switch the SIDEBAND switch counter-clockwise (the 'non-X' position) and the MODE switch to X-CW. I don't have a TR-4C set up at the moment, but I believe the KEY has to be closed. IF you have a key plugged in, it must be shorted. IF you do NOT have a key plugged in, there is a contact on the key jack that is 'supposed' to short the key. IF this contact does not MAKE properly you would see what I think you are describing. The goal here is to put the transceiver into TRANSMIT mode (X-CW) with the 'non' X SIDEBAND selected and the MIC GAIN at minimum. This should register the BIAS current of the PA stage since you're essentially in SSB with no audio applied, resulting in only the suppressed carrier and no PLATE current. My guess is that either a KEY is plugged in and open, or the 'shorting' jack, isn't! Try just inserting a phone plug into the KEY jack several times to see if that shorting contact will close as it should. Otherwise just insert a shorted phone plug into the KEY jack. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: A few weeks ago I started working on putting a TR-4C back on the air. I posed a question about the bias adjustment. I finally got back to working on the transceiver and still have some questions. I have followed all the information that has been sent to other people with bias problems, but that info has not helped me. My problem is that the bias current is not displayed or changed on the Plate Current meter when I adjust the bias control. I can measure and adjust the bias voltage on the final grids so I know the system is working, I just can't measure the current. I have done most of the suggested things: loosen and retighten most ground screws, pulled and checked all tubes and used Deoxit on the pins and reinserted multiple times to clean the pins and sockets and cleaned the contacts on the relays. The 48 volt relay only has 26 volts on the pins, but it appears to pull in okay and work. Is 26 volts normal? Using the Drake manual instructions for bias adjust, no plate current reading is detected even though
Re: [Drakelist] TR-4C Bias Adjustment
- Original Message - From: Donley donley...@comcast.net To: k4...@mindspring.com; drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 8:57 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Garey, Sorry about the delay in my response. Time gets away from me. I acquired the TR-4C several years ago and my normal procedure is to put a new acquisition on the bench and run it through a simple use test. Then I tag it with the information, working or not, and put it on the shelf for later free time. This one has no tag, so my procedure must have failed. I don't remember if the bias worked or not. My guess is not. Yes, the receiver works just fine. The RV-4C is on the shelf, not connected. VOX and ANTI-VOX are set at mid-range. The transmitter works fine also, I just can't measure the bias current. Can I assume that the bias current is close to 100 mA if the bias voltage is ~ -60 VDC? It seems like there must be an open in the meter circuit when switched to set the bias. That should involve switches and relay contacts in the circuit. I am not very good at tracing circuits on the schematic when they start running through switches. In SSB mode, NON-X position, grounding the 'TIP' MIC connector pulls in the relay. I should probably order a new relay and try it, but the old one appeared to work when I had it out and open for cleaning. One set of contacts was somewhat dirty but I had good continuity after cleaning. Richard Assuming the TR-4C is not much different from the TR-4 the problem you describe is very puzzling. The transmitter settings for adjusting the bias do not affect the metering circuit at all. What they do is to energize the output tubes without any drive. To set bias the controls are set so that the rig is in CW but the sideband switch is in the wrong position, i.e. non-X. That shifts the CW signal to the wrong filter so that it doesn't get through to the driver stages. The final amp tubes are still energized and draw whatever quiescent current the bias is set for. If there is excessive bias there will be no current drawn, however, the transmitter will still put out a signal and draw plate current when _driven_. The difference is that the output will not be at the correct level and there may be distortion. If you have not done the following do it: Disconnect the power supply from the transmitter, short the pins on the socket that go to the AC switch so that the supply powers up. Measure the voltage at the bias terminal and see how much difference the bias adustment pot makes. You should be able to vary it over a rather large range. The corrct setting for the TR-4/C is about -60 volts. If this works OK take the short off and reconnect it to the transmitter. Now, check at the feed through terminals going to the final cage under the chassis to see if you are getting the correct bias voltage there. Next, check the voltage drop across the individual cathode resistors of the final tubes. I don't remember the correct voltage to see there but Garey or someone will know. If the tubes are truely NOT drawing current there will be no or very little drop across these resistors. The upper meter is switched between reading plate current and reading power output by the pull switch switch which is also the control for its sensitivity for output. If this switch is not making good contact it might make the meter read low or not at all in the plate current position, BUT, it will read low or not at all all the time, not just for adjusting the bias. There are two things that can cause a tube to draw no quiescent current when the plate voltage is present. 1, its biased beyond cut-off, 2, the screen voltage is too low or absent. If the screen is too low the tube is no longer operating in the intended mode. Its possible for it to have output when driven but not otherwise. It will act as though its a Class B or C circuit. So, check the screen voltage carefully _right at the tube_. Also check the bias voltage at the tube. Its possible that the maximum bias from the power supply is sufficient to cut the tube off. Again, it will still put out when driven but will be operating in the wrong mode and the output will be distorted. I can't find data on running 6JB6 tubes other than TV sweep mode althought I think there is such data on the Drake web site. It would be useful to know what the cut-off bias is for the plate and screen voltages in the TR-4/C. In any case we know what the normal operating voltages are. I think we have been sidetracked by the meter and relay. If this is all way off base I am sure someone will tell me about it:-) -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Richard, I think you need to find the cause of the low voltage (230V vs. 250-260V) and fix that first. The meter circuit does not change by switching the sideband. As Garey said it's only job is to choose the filter and the lamp. The low screen voltage will certainly affect the plate current. In the X-CW mode, the carrier frequency is shifted and the side-tone is fed to the balanced modulator. Correct me if I am wrong, but my understanding is that since the carrier is shifted, this signal can only pass through the filter selected at the X position. At the non-X position, no signal goes through. A lower screen voltage negatively affects the plate current. A lighter bias may be required, but AC-4 may not be able to supply it. Now, even in this case, if you push signal to the control grid, there will be some plate current. By advancing the TX gain, you did exactly that. But as you know that's not the idling current (we are providing input) we want to check when setting the bias. If the screen voltage is not too low, you can still see a good power output. But without proper biasing, the linearity will suffer. Kihwal, K9SUL From: Donley donley...@comcast.net To: k4...@mindspring.com; drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 10:57 AM Subject: Re: [Drakelist] TR-4C Bias Adjustment Garey, Sorry about the delay in my response. Time gets away from me. I acquired the TR-4C several years ago and my normal procedure is to put a new acquisition on the bench and run it through a simple use test. Then I tag it with the information, working or not, and put it on the shelf for later free time. This one has no tag, so my procedure must have failed. I don't remember if the bias worked or not. My guess is not. Yes, the receiver works just fine. The RV-4C is on the shelf, not connected. VOX and ANTI-VOX are set at mid-range. The transmitter works fine also, I just can't measure the bias current. Can I assume that the bias current is close to 100 mA if the bias voltage is ~ -60 VDC? It seems like there must be an open in the meter circuit when switched to set the bias. That should involve switches and relay contacts in the circuit. I am not very good at tracing circuits on the schematic when they start running through switches. In SSB mode, NON-X position, grounding the 'TIP' MIC connector pulls in the relay. I should probably order a new relay and try it, but the old one appeared to work when I had it out and open for cleaning. One set of contacts was somewhat dirty but I had good continuity after cleaning. Richard Richard - Probably should have asked this question a while ago, but has this transmitter EVER worked, to your knowledge? Does the receiver work?? Do you have an RV-4(C) connected? Verify that the VOX and ANTI-VOX controls on the right side are about mid-range. Unless something has been rewired, the Cathode line of the PA should read that 0.3 to 0.4 VDC ANY time the relay (the four pole one near the power connector) is energized, regardless of ANY other switch position. The Cathode lead comes through the feedthrough cap on the PA section shield, goes to R45 (2 ohms, on the board with the relay) and is hard wired from the other end of R45 to the relay contact. This contact is grounded any time the relay is energized, grounding the PA Cathodes. When it's in SSB, in the NON-X position, try grounding the 'TIP' of the MIC connector and see if the relay pulls in. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Garey, I replaced the 6EV7 and there was no change. The plate voltage on the 6EV7 measures a little low at 230 VDC (supposed to 260). This makes the voltage on the relay lower than the 48 VDC (measures about 26 V if I remember correctly, but it seems to pull in okay). I measured the four voltages in all combinations of the sideband switch and the mode switch settings (sideband switch in non-X position and mode switch in SSB position and then in X-CW position). Then (sideband switch in X position and mode switch in SSB position and then X-CW position). The four plate voltage measurements were 687 to 690 VDC. The four screen voltage measurements were 230 to 236 VDC (a little low if 260 is correct). The four grid voltage measurements were around -60 VDC. When the Mode switch was in the SSB position, the cathode voltage was 156 VDC for each position of the sideband switch. When the Mode switch was in the X-CW position, the cathode voltage was 0.3 to 0.4 VDC. When I said I could adjust the bias voltage in the sideband X position, I didn't tell you that to do that I had to advance the transmitter gain control slightly to get 100 mA. But when I switched back to sideband non-X position, the current dropped to zero with no control by the bias knob
Re: [Drakelist] TR-4C Bias Adjustment
Kihwal - I agree with most of what you said. The Screen voltage is slightly low, most likely as a result of leakage in the AC-4 filter caps. But I do NOT believe it has any significant effect on this problem as he is able to get full power in the X-CW position. You are correct on the X-CW shifting the Carrier Osc (via relay K2) so that the CARRIER signal will go through one of the filters. This configuration is used for both tune-up and CW operation. The SIDETONE is NOT used for this purpose in the TR-4C, only to operate the VOX circuit. In the T-4XC, the CO is shifted for CW operation. However, in TUNE mode the SIDETONE IS applied to the Balanced Modulator, generating a single tone SSB signal, and the CO is NOT shifted. The key here is that these Cathodes are NOT grounded in either SSB position. I believe that is the result of the PTT/VOX circuit NOT pulling in the relay in that switch position. Grounding the tip of the MIC connector causes the relay to pull in, and I believe that will cause the PA Cathodes to read the correct near zero reading rather than the 156 VDC he measured. The PLATE meter should then read correctly. We'll see! :-) I'm now thinking the problem is in the VOX circuitry. 73, Garey - K4OAH Glen Allen, VA Kihwal Lee wrote: Richard, I think you need to find the cause of the low voltage (230V vs. 250-260V) and fix that first. The meter circuit does not change by switching the sideband. As Garey said it's only job is to choose the filter and the lamp. The low screen voltage will certainly affect the plate current. In the X-CW mode, the carrier frequency is shifted and the side-tone is fed to the balanced modulator. Correct me if I am wrong, but my understanding is that since the carrier is shifted, this signal can only pass through the filter selected at the X position. At the non-X position, no signal goes through. A lower screen voltage negatively affects the plate current. A lighter bias may be required, but AC-4 may not be able to supply it. Now, even in this case, if you push signal to the control grid, there will be some plate current. By advancing the TX gain, you did exactly that. But as you know that's not the idling current (we are providing input) we want to check when setting the bias. If the screen voltage is not too low, you can still see a good power output. But without proper biasing, the linearity will suffer. Kihwal, K9SUL *From:* Donley donley...@comcast.net *To:* k4...@mindspring.com; drakelist Drakelist@zerobeat.net *Sent:* Tuesday, July 12, 2011 10:57 AM *Subject:* Re: [Drakelist] TR-4C Bias Adjustment Garey, Sorry about the delay in my response. Time gets away from me. I acquired the TR-4C several years ago and my normal procedure is to put a new acquisition on the bench and run it through a simple use test. Then I tag it with the information, working or not, and put it on the shelf for later free time. This one has no tag, so my procedure must have failed. I don't remember if the bias worked or not. My guess is not. Yes, the receiver works just fine. The RV-4C is on the shelf, not connected. VOX and ANTI-VOX are set at mid-range. The transmitter works fine also, I just can't measure the bias current. Can I assume that the bias current is close to 100 mA if the bias voltage is ~ -60 VDC? It seems like there must be an open in the meter circuit when switched to set the bias. That should involve switches and relay contacts in the circuit. I am not very good at tracing circuits on the schematic when they start running through switches. In SSB mode, NON-X position, grounding the 'TIP' MIC connector pulls in the relay. I should probably order a new relay and try it, but the old one appeared to work when I had it out and open for cleaning. One set of contacts was somewhat dirty but I had good continuity after cleaning. Richard Richard - Probably should have asked this question a while ago, but has this transmitter EVER worked, to your knowledge? Does the receiver work?? Do you have an RV-4(C) connected? Verify that the VOX and ANTI-VOX controls on the right side are about mid-range. Unless something has been rewired, the Cathode line of the PA should read that 0.3 to 0.4 VDC ANY time the relay (the four pole one near the power connector) is energized, regardless of ANY other switch position. The Cathode lead comes through the feedthrough cap on the PA section shield, goes to R45 (2 ohms, on the board with the relay) and is hard wired from the other end of R45 to the relay contact. This contact is grounded any time the relay is energized, grounding the PA Cathodes. When it's in SSB, in the NON-X position, try grounding the 'TIP' of the MIC connector and see if the relay pulls in. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service
Re: [Drakelist] TR-4C Bias Adjustment
Garey, Thanks for the clarification. As always, you are the source! As for the floating K, I think it's normal when the mode switch is in the SSB position and the PTT is not pressed. I know you wanted Richard to measure the voltage during TX, but I think he measured it while not transmitting (i.e. ptt not pressed). To me the problem seems that the final tubes stays cutoff within the bias voltage range provided by the AC-4. I thought it was the screen voltage issue, but again I am relatively new to this hollow state technology so it was just a guess. Kihwal, K9SUL From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 12:57 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Kihwal - I agree with most of what you said. The Screen voltage is slightly low, most likely as a result of leakage in the AC-4 filter caps. But I do NOT believe it has any significant effect on this problem as he is able to get full power in the X-CW position. You are correct on the X-CW shifting the Carrier Osc (via relay K2) so that the CARRIER signal will go through one of the filters. This configuration is used for both tune-up and CW operation. The SIDETONE is NOT used for this purpose in the TR-4C, only to operate the VOX circuit. In the T-4XC, the CO is shifted for CW operation. However, in TUNE mode the SIDETONE IS applied to the Balanced Modulator, generating a single tone SSB signal, and the CO is NOT shifted. The key here is that these Cathodes are NOT grounded in either SSB position. I believe that is the result of the PTT/VOX circuit NOT pulling in the relay in that switch position. Grounding the tip of the MIC connector causes the relay to pull in, and I believe that will cause the PA Cathodes to read the correct near zero reading rather than the 156 VDC he measured. The PLATE meter should then read correctly. We'll see! :-) I'm now thinking the problem is in the VOX circuitry. 73, Garey - K4OAH Glen Allen, VA Kihwal Lee wrote: Richard, I think you need to find the cause of the low voltage (230V vs. 250-260V) and fix that first. The meter circuit does not change by switching the sideband. As Garey said it's only job is to choose the filter and the lamp. The low screen voltage will certainly affect the plate current. In the X-CW mode, the carrier frequency is shifted and the side-tone is fed to the balanced modulator. Correct me if I am wrong, but my understanding is that since the carrier is shifted, this signal can only pass through the filter selected at the X position. At the non-X position, no signal goes through. A lower screen voltage negatively affects the plate current. A lighter bias may be required, but AC-4 may not be able to supply it. Now, even in this case, if you push signal to the control grid, there will be some plate current. By advancing the TX gain, you did exactly that. But as you know that's not the idling current (we are providing input) we want to check when setting the bias. If the screen voltage is not too low, you can still see a good power output. But without proper biasing, the linearity will suffer. Kihwal, K9SUL *From:* Donley donley...@comcast.net *To:* k4...@mindspring.com; drakelist Drakelist@zerobeat.net *Sent:* Tuesday, July 12, 2011 10:57 AM *Subject:* Re: [Drakelist] TR-4C Bias Adjustment Garey, Sorry about the delay in my response. Time gets away from me. I acquired the TR-4C several years ago and my normal procedure is to put a new acquisition on the bench and run it through a simple use test. Then I tag it with the information, working or not, and put it on the shelf for later free time. This one has no tag, so my procedure must have failed. I don't remember if the bias worked or not. My guess is not. Yes, the receiver works just fine. The RV-4C is on the shelf, not connected. VOX and ANTI-VOX are set at mid-range. The transmitter works fine also, I just can't measure the bias current. Can I assume that the bias current is close to 100 mA if the bias voltage is ~ -60 VDC? It seems like there must be an open in the meter circuit when switched to set the bias. That should involve switches and relay contacts in the circuit. I am not very good at tracing circuits on the schematic when they start running through switches. In SSB mode, NON-X position, grounding the 'TIP' MIC connector pulls in the relay. I should probably order a new relay and try it, but the old one appeared to work when I had it out and open for cleaning. One set of contacts was somewhat dirty but I had good continuity after cleaning. Richard Richard - Probably should have asked this question a while ago, but has this transmitter EVER worked, to your knowledge? Does
Re: [Drakelist] TR-4C Bias Adjustment
Kihwal - When we're several hundred miles away, we are ALL guessing! :-) Yes, the PA Cathodes are only grounded when the relay is closed. Richard says that he has approximately -60 VDC on the Grids, which is about right. With the MODE switch in X-CW the relay should be closed by the SIDETONE signal applied to the VOX circuit input via switch S2 B (rear). In SSB, the SIDETONE is disabled via S2 B(front) and the VOX is driven by the MIC AMP output. With no modulation, the VOX should NOT pick up. When you switch to X-CW with the SIDEBAND switch in NON-X, the transmitter is keyed, but the filter selected will NOT pass the shifted Carrier Oscillator frequency. So the PA is keyed, but no drive is applied and the IDLE current can be set. I'm sure I'm missing something simple. We do this for fun ... We do this for fun ... We do this for ...? Keying the PTT should allow the IDLE current to flow and be measured with no AF drive, in SSB. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Kihwal Lee wrote: Garey, Thanks for the clarification. As always, you are the source! As for the floating K, I think it's normal when the mode switch is in the SSB position and the PTT is not pressed. I know you wanted Richard to measure the voltage during TX, but I think he measured it while not transmitting (i.e. ptt not pressed). To me the problem seems that the final tubes stays cutoff within the bias voltage range provided by the AC-4. I thought it was the screen voltage issue, but again I am relatively new to this hollow state technology so it was just a guess. Kihwal, K9SUL *From:* Garey Barrell k4...@mindspring.com *To:* drakelist Drakelist@zerobeat.net *Sent:* Tuesday, July 12, 2011 12:57 PM *Subject:* Re: [Drakelist] TR-4C Bias Adjustment Kihwal - I agree with most of what you said. The Screen voltage is slightly low, most likely as a result of leakage in the AC-4 filter caps. But I do NOT believe it has any significant effect on this problem as he is able to get full power in the X-CW position. You are correct on the X-CW shifting the Carrier Osc (via relay K2) so that the CARRIER signal will go through one of the filters. This configuration is used for both tune-up and CW operation. The SIDETONE is NOT used for this purpose in the TR-4C, only to operate the VOX circuit. In the T-4XC, the CO is shifted for CW operation. However, in TUNE mode the SIDETONE IS applied to the Balanced Modulator, generating a single tone SSB signal, and the CO is NOT shifted. The key here is that these Cathodes are NOT grounded in either SSB position. I believe that is the result of the PTT/VOX circuit NOT pulling in the relay in that switch position. Grounding the tip of the MIC connector causes the relay to pull in, and I believe that will cause the PA Cathodes to read the correct near zero reading rather than the 156 VDC he measured. The PLATE meter should then read correctly. We'll see! :-) I'm now thinking the problem is in the VOX circuitry. 73, Garey - K4OAH Glen Allen, VA Kihwal Lee wrote: Richard, I think you need to find the cause of the low voltage (230V vs. 250-260V) and fix that first. The meter circuit does not change by switching the sideband. As Garey said it's only job is to choose the filter and the lamp. The low screen voltage will certainly affect the plate current. In the X-CW mode, the carrier frequency is shifted and the side-tone is fed to the balanced modulator. Correct me if I am wrong, but my understanding is that since the carrier is shifted, this signal can only pass through the filter selected at the X position. At the non-X position, no signal goes through. A lower screen voltage negatively affects the plate current. A lighter bias may be required, but AC-4 may not be able to supply it. Now, even in this case, if you push signal to the control grid, there will be some plate current. By advancing the TX gain, you did exactly that. But as you know that's not the idling current (we are providing input) we want to check when setting the bias. If the screen voltage is not too low, you can still see a good power output. But without proper biasing, the linearity will suffer. Kihwal, K9SUL *From:* Donley donley...@comcast.net mailto:donley...@comcast.net *To:* k4...@mindspring.com mailto:k4...@mindspring.com; drakelist Drakelist@zerobeat.net mailto:Drakelist@zerobeat.net *Sent:* Tuesday, July 12, 2011 10:57 AM *Subject:* Re: [Drakelist] TR-4C Bias Adjustment Garey, Sorry about the delay in my response. Time gets away from me. I acquired the TR-4C several years ago and my normal procedure is to put a new acquisition on the bench
Re: [Drakelist] TR-4C Bias Adjustment
Richard - I thought I asked this earlier, but I can't find it now. You said you can get full output from the transmitter and read the PLATE current on the meter in X-CW. Does the PLATE current dip at maximum output as it should? What is the dipped PLATE current when tuned for full output? Push and release the LOAD control several times. 73, Garey - K4OAH Glen Allen, VA Garey Barrell wrote: Kihwal - When we're several hundred miles away, we are ALL guessing! :-) Yes, the PA Cathodes are only grounded when the relay is closed. Richard says that he has approximately -60 VDC on the Grids, which is about right. With the MODE switch in X-CW the relay should be closed by the SIDETONE signal applied to the VOX circuit input via switch S2 B (rear). In SSB, the SIDETONE is disabled via S2 B(front) and the VOX is driven by the MIC AMP output. With no modulation, the VOX should NOT pick up. When you switch to X-CW with the SIDEBAND switch in NON-X, the transmitter is keyed, but the filter selected will NOT pass the shifted Carrier Oscillator frequency. So the PA is keyed, but no drive is applied and the IDLE current can be set. I'm sure I'm missing something simple. We do this for fun ... We do this for fun ... We do this for ...? Keying the PTT should allow the IDLE current to flow and be measured with no AF drive, in SSB. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Kihwal Lee wrote: Garey, Thanks for the clarification. As always, you are the source! As for the floating K, I think it's normal when the mode switch is in the SSB position and the PTT is not pressed. I know you wanted Richard to measure the voltage during TX, but I think he measured it while not transmitting (i.e. ptt not pressed). To me the problem seems that the final tubes stays cutoff within the bias voltage range provided by the AC-4. I thought it was the screen voltage issue, but again I am relatively new to this hollow state technology so it was just a guess. Kihwal, K9SUL *From:* Garey Barrell k4...@mindspring.com *To:* drakelist Drakelist@zerobeat.net *Sent:* Tuesday, July 12, 2011 12:57 PM *Subject:* Re: [Drakelist] TR-4C Bias Adjustment Kihwal - I agree with most of what you said. The Screen voltage is slightly low, most likely as a result of leakage in the AC-4 filter caps. But I do NOT believe it has any significant effect on this problem as he is able to get full power in the X-CW position. You are correct on the X-CW shifting the Carrier Osc (via relay K2) so that the CARRIER signal will go through one of the filters. This configuration is used for both tune-up and CW operation. The SIDETONE is NOT used for this purpose in the TR-4C, only to operate the VOX circuit. In the T-4XC, the CO is shifted for CW operation. However, in TUNE mode the SIDETONE IS applied to the Balanced Modulator, generating a single tone SSB signal, and the CO is NOT shifted. The key here is that these Cathodes are NOT grounded in either SSB position. I believe that is the result of the PTT/VOX circuit NOT pulling in the relay in that switch position. Grounding the tip of the MIC connector causes the relay to pull in, and I believe that will cause the PA Cathodes to read the correct near zero reading rather than the 156 VDC he measured. The PLATE meter should then read correctly. We'll see! :-) I'm now thinking the problem is in the VOX circuitry. 73, Garey - K4OAH Glen Allen, VA Kihwal Lee wrote: Richard, I think you need to find the cause of the low voltage (230V vs. 250-260V) and fix that first. The meter circuit does not change by switching the sideband. As Garey said it's only job is to choose the filter and the lamp. The low screen voltage will certainly affect the plate current. In the X-CW mode, the carrier frequency is shifted and the side-tone is fed to the balanced modulator. Correct me if I am wrong, but my understanding is that since the carrier is shifted, this signal can only pass through the filter selected at the X position. At the non-X position, no signal goes through. A lower screen voltage negatively affects the plate current. A lighter bias may be required, but AC-4 may not be able to supply it. Now, even in this case, if you push signal to the control grid, there will be some plate current. By advancing the TX gain, you did exactly that. But as you know that's not the idling current (we are providing input) we want to check when setting the bias. If the screen voltage is not too low, you can still see a good power output. But without proper biasing, the linearity will suffer. Kihwal, K9SUL *From:* Donley donley...@comcast.net mailto:donley
Re: [Drakelist] TR-4C Bias Adjustment
hi Richard, Garey must be having a late supper tonite. I just got back from mine, so I'll chip in. Garey's helped me a lot over the yrs. your # 1 2, indicate that you do see some idle current, and your later measurements of voltage at the cathode resistors confirms that shows that you do have approx 30 ma. of idle current with the present bias setting (not enough, should be ~100 ma.) Use ohms law with the resistance of those cathode resistors and the voltage across them to get that figure. Add the 3 figures to get total. Caculation also shows that the 350ma you see at max. is approx. a correct reading, but since it isn't at a dip, the finals are probably oscillating on some VHF freq., or wide band. Not good. Might just be poor neutralization. Garey's just helped me with a problem like that in a TR-3. The variation in lights vs band for SB is normal, you do have to change to get the proper SB light for the band you're operating, lower for 40 80/75, upper for 20, 15 10. To tune up you always need to be in the X position, no matter what the light says. I don't know what you mean by, The 80, 15 and 10 M. lights don't seem right in either SIDEBAND position., refer to the above paragraph, maybe that helps. I hope this helps a little, in Garey's temporary absence. 73, Al, W8UT www.boatanchors.org www.hammarlund.info There is nothing -- absolutely nothing -- half so much worth doing as simply messing about in boats Ratty, to Mole On 7/12/2011 7:25 PM, Donley wrote: Garey, I have gone through my list of task assignments and have some results. To answer your questions, 1. With microphone installed, PA cathode voltage goes to almost zero with mike button depressed. 2. But there is no idle current in this test. 3. Plate current does increase and fluctuate with puffing into the mike ( I am too old to huff, just puff) but I have to add some XMTR GAIN to get any plate current. 4. When I said I could tune up the transmitter, I may have fooled myself. I can get 150 to 175 watts out into a wattmeter and dummy load, but I can't dip the plate current. The plate current maximizes at about 350 mA. in the middle of the PLATE adjustment and falls off to very low at either end of the adjustment. Other measurements requested by the other Richard, Measurements at the AC-4 plug, 693 VDC (pins 10-7), 282 VDC (pins 11-7) and the bias voltage can be varied from -49 to -92 VDC (pins 9-7). On the base of the finals those measurements are 690 VDC (at the feedthrough), 236 VDC and -36 to -70 VDC. Also the voltage drops on the three cathode resistors are 0.13, 0.18 and 0.17 VDC when in the bias current adjust mode. If I add some drive to get 350 mA plate current, those voltages go to about -2.5 VDC each. One other thing that I noticed is which sideband lights are lit for various band choices. In SIDEBAND X position, the lights are as follows: 80 M. Upper Light ? 40 M. Lower Light 20 M. Upper Light 15 M. and all 10 M. positions Lower Light ? The lights are reversed for SIDEBAND NON-X position. This means that I have to change the SIDEBAND switch when I change from 40 to 80 M. Is that correct for the TR-4C? The 80, 15 and 10 M. lights don't seem right in either SIDEBAND position. I am doing all my measurements on 40 M. because that is the only antenna that I currently have in place. I will gladly take on more chores to find a fix. Richard - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 3:57 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I thought I asked this earlier, but I can't find it now. You said you can get full output from the transmitter and read the PLATE current on the meter in X-CW. Does the PLATE current dip at maximum output as it should? What is the dipped PLATE current when tuned for full output? Push and release the LOAD control several times. 73, Garey - K4OAH Glen Allen, VA Garey Barrell wrote: Kihwal - When we're several hundred miles away, we are ALL guessing! :-) Yes, the PA Cathodes are only grounded when the relay is closed. Richard says that he has approximately -60 VDC on the Grids, which is about right. With the MODE switch in X-CW the relay should be closed by the SIDETONE signal applied to the VOX circuit input via switch S2 B (rear). In SSB, the SIDETONE is disabled via S2 B(front) and the VOX is driven by the MIC AMP output. With no modulation, the VOX should NOT pick up. When you switch to X-CW with the SIDEBAND switch in NON-X, the transmitter is keyed, but the filter selected will NOT pass the shifted Carrier Oscillator frequency. So the PA is keyed, but no drive is applied and the IDLE current can be set. I'm sure I'm missing something simple. We do this for fun ... We do this for fun ... We do this for ...? Keying the PTT should allow the IDLE current to flow and be measured with no AF drive, in SSB. 73, Garey - K4OAH Glen Allen, VA
Re: [Drakelist] TR-4C Bias Adjustment
- Original Message - From: Donley donley...@comcast.net To: k4...@mindspring.com; drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 4:25 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Garey, I have gone through my list of task assignments and have some results. To answer your questions, 1. With microphone installed, PA cathode voltage goes to almost zero with mike button depressed. 2. But there is no idle current in this test. 3. Plate current does increase and fluctuate with puffing into the mike ( I am too old to huff, just puff) but I have to add some XMTR GAIN to get any plate current. 4. When I said I could tune up the transmitter, I may have fooled myself. I can get 150 to 175 watts out into a wattmeter and dummy load, but I can't dip the plate current. The plate current maximizes at about 350 mA. in the middle of the PLATE adjustment and falls off to very low at either end of the adjustment. Other measurements requested by the other Richard, Measurements at the AC-4 plug, 693 VDC (pins 10-7), 282 VDC (pins 11-7) and the bias voltage can be varied from -49 to -92 VDC (pins 9-7). On the base of the finals those measurements are 690 VDC (at the feedthrough), 236 VDC and -36 to -70 VDC. Also the voltage drops on the three cathode resistors are 0.13, 0.18 and 0.17 VDC when in the bias current adjust mode. If I add some drive to get 350 mA plate current, those voltages go to about -2.5 VDC each. One other thing that I noticed is which sideband lights are lit for various band choices. In SIDEBAND X position, the lights are as follows: 80 M.Upper Light? 40 M.Lower Light 20 M.Upper Light 15 M. and all 10 M. positionsLower Light? The lights are reversed for SIDEBAND NON-X position. This means that I have to change the SIDEBAND switch when I change from 40 to 80 M. Is that correct for the TR-4C? The 80, 15 and 10 M. lights don't seem right in either SIDEBAND position. I am doing all my measurements on 40 M. because that is the only antenna that I currently have in place. I will gladly take on more chores to find a fix. Richard The sideband lights do change from band to band depending on the way the oscillator frequencies are in relation to each other. For AM and CW the sideband carrier oscillator is shifted a little so that the signal can get though one of the sideband filters, the X position shows that. The bias is adjusted with the sideband switch on the other side so that no drive can get through, that way the only current measured is the quescent current of the tube. If no current shows on the meter, and nothing is wrong with the metering circuit, it means that the tube is not drawing any current when in this condition. The final amplifiers of the TR-4 run in Class AB-1 and should draw some current at all times. If none is drawn, as I suggested before, either the bias or the screen voltage may be wrong. Your measurements are close to those in the handbook chart. A suggestion: I am very puzzled by the meter not showing a dip when tuning. If you can messure the voltage at C-73, this is the feedthrough for the cathodes, its the feedthrough on the far left of the cage (with the tubes on top) all by itself. Hang a meter on it and do a normal tuning, beginning with mimimal drive and look for a dip at resonance. If you see a dip at this point the meter is stuck looking at output rather than plate current and the problem is probably the slide switch. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
- Original Message - From: Donley donley...@comcast.net To: k4...@mindspring.com; drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 4:25 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Another thought, If the meter switch is stuck reading output rather than plate current its likely the adjusting pot will work, that's the knob that you pull out to switch the meter. Get a reading on the meter and rotate this control. If you are actually reading plate current it will make no difference, but if you are reading output it will run the meter up and down. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Richard - Does the LOAD control move in and out, physically? PULL OUT on the LOAD control and see if you get BIAS current 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: Garey, I have gone through my list of task assignments and have some results. To answer your questions, 1. With microphone installed, PA cathode voltage goes to almost zero with mike button depressed. 2. But there is no idle current in this test. 3. Plate current does increase and fluctuate with puffing into the mike ( I am too old to huff, just puff) but I have to add some XMTR GAIN to get any plate current. 4. When I said I could tune up the transmitter, I may have fooled myself. I can get 150 to 175 watts out into a wattmeter and dummy load, but I can't dip the plate current. The plate current maximizes at about 350 mA. in the middle of the PLATE adjustment and falls off to very low at either end of the adjustment. Other measurements requested by the other Richard, Measurements at the AC-4 plug, 693 VDC (pins 10-7), 282 VDC (pins 11-7) and the bias voltage can be varied from -49 to -92 VDC (pins 9-7). On the base of the finals those measurements are 690 VDC (at the feedthrough), 236 VDC and -36 to -70 VDC. Also the voltage drops on the three cathode resistors are 0.13, 0.18 and 0.17 VDC when in the bias current adjust mode. If I add some drive to get 350 mA plate current, those voltages go to about -2.5 VDC each. One other thing that I noticed is which sideband lights are lit for various band choices. In SIDEBAND X position, the lights are as follows: 80 M.Upper Light? 40 M.Lower Light 20 M.Upper Light 15 M. and all 10 M. positionsLower Light? The lights are reversed for SIDEBAND NON-X position. This means that I have to change the SIDEBAND switch when I change from 40 to 80 M. Is that correct for the TR-4C? The 80, 15 and 10 M. lights don't seem right in either SIDEBAND position. I am doing all my measurements on 40 M. because that is the only antenna that I currently have in place. I will gladly take on more chores to find a fix. Richard - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 3:57 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I thought I asked this earlier, but I can't find it now. You said you can get full output from the transmitter and read the PLATE current on the meter in X-CW. Does the PLATE current dip at maximum output as it should? What is the dipped PLATE current when tuned for full output? Push and release the LOAD control several times. 73, Garey - K4OAH Glen Allen, VA Garey Barrell wrote: Kihwal - When we're several hundred miles away, we are ALL guessing! :-) Yes, the PA Cathodes are only grounded when the relay is closed. Richard says that he has approximately -60 VDC on the Grids, which is about right. With the MODE switch in X-CW the relay should be closed by the SIDETONE signal applied to the VOX circuit input via switch S2 B (rear). In SSB, the SIDETONE is disabled via S2 B(front) and the VOX is driven by the MIC AMP output. With no modulation, the VOX should NOT pick up. When you switch to X-CW with the SIDEBAND switch in NON-X, the transmitter is keyed, but the filter selected will NOT pass the shifted Carrier Oscillator frequency. So the PA is keyed, but no drive is applied and the IDLE current can be set. I'm sure I'm missing something simple. We do this for fun ... We do this for fun ... We do this for ...? Keying the PTT should allow the IDLE current to flow and be measured with no AF drive, in SSB. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Kihwal Lee wrote: Garey, Thanks for the clarification. As always, you are the source! As for the floating K, I think it's normal when the mode switch is in the SSB position and the PTT is not pressed. I know you wanted Richard to measure the voltage during TX, but I think he measured it while not transmitting (i.e. ptt not pressed). To me the problem seems that the final tubes stays cutoff within the bias voltage range provided by the AC-4. I thought it was the screen voltage issue, but again I am relatively new to this hollow state technology so it was just a guess. Kihwal, K9SUL *From:* Garey Barrell k4...@mindspring.com *To:* drakelist Drakelist@zerobeat.net *Sent:* Tuesday, July 12, 2011 12:57 PM *Subject:* Re: [Drakelist] TR-4C Bias Adjustment Kihwal - I agree with most of what you said. The Screen voltage is slightly low, most likely as a result of leakage in the AC-4 filter caps. But I do NOT believe it has any significant effect on this problem as he is able
Re: [Drakelist] TR-4C Bias Adjustment
Richard - This is what I referred to in my last message. There is no adjusting pot on the TR-4C, but the meter is switched from Plate current to output meter. That's why I said to push and pull the LOAD control a couple of times. There should be a hairpin shaped spring on the LOAD control shaft that pushes the LOAD knob OUT for PLATE current reading and you PUSH it IN for RF OUTPUT reading. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Richard Knoppow wrote: - Original Message - From: Donley donley...@comcast.net To: k4...@mindspring.com; drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 4:25 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Another thought, If the meter switch is stuck reading output rather than plate current its likely the adjusting pot will work, that's the knob that you pull out to switch the meter. Get a reading on the meter and rotate this control. If you are actually reading plate current it will make no difference, but if you are reading output it will run the meter up and down. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C Load Switch...
My load switch is a PUSH switch ... it does not pull. You push in for RF output indications ... left alone for normal cathode current. Also, lights ... on mine ... 40M Sideband X = LSB. 80M Sideband X = is USB .. you need to switch to the left (non-X) position for LSB. Bill, W0LPQ ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Load Switch...
Assuming that the spring is not broken! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com William Lambing wrote: My load switch is a PUSH switch ... it does not pull. You push in for RF output indications ... left alone for normal cathode current. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
- Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 6:36 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - This is what I referred to in my last message. There is no adjusting pot on the TR-4C, but the meter is switched from Plate current to output meter. That's why I said to push and pull the LOAD control a couple of times. There should be a hairpin shaped spring on the LOAD control shaft that pushes the LOAD knob OUT for PLATE current reading and you PUSH it IN for RF OUTPUT reading. 73, Garey - K4OAH Glen Allen, VA That's obviously a differenc I missed between the TR-4 and TR-4C but the idea is the same. If the meter is stuck reading output it could behave as described. That's why I suggested an independant measurement of cathode current. If he gets a dip there but not on the meter the switch is probably no good or something else is causing the meter to read output all the time. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Completed tasks. Adjusted bias control until 0.5 VDC across cathode resistor, equals 33 mA, three resistors in parallel equals 100 mA total bias current. Bias voltage is -55 VDC at this point. No bias current measurement on plate current meter (actually has been just a slight wiggle all along, but nothing more than a half pointer width wiggle). C-73 is not a feedthrough, what point should be measured? The LOAD control spring is intact and functioning. In tune procedure, PLATE control does not dip, it is maximum about mid-range and reduces to near zero on either side of peak. LOAD control pushed in or out, peak occurs about mid-range and falls off on either side of peak. Is this pointing to the RF output slide switch circuit, possibly a shorted switch? - Original Message - From: Richard Knoppow 1oldle...@ix.netcom.com To: k4...@mindspring.com; drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 10:26 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment - Original Message - From: Garey Barrell k4...@mindspring.com To: drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 6:36 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - This is what I referred to in my last message. There is no adjusting pot on the TR-4C, but the meter is switched from Plate current to output meter. That's why I said to push and pull the LOAD control a couple of times. There should be a hairpin shaped spring on the LOAD control shaft that pushes the LOAD knob OUT for PLATE current reading and you PUSH it IN for RF OUTPUT reading. 73, Garey - K4OAH Glen Allen, VA That's obviously a differenc I missed between the TR-4 and TR-4C but the idea is the same. If the meter is stuck reading output it could behave as described. That's why I suggested an independant measurement of cathode current. If he gets a dip there but not on the meter the switch is probably no good or something else is causing the meter to read output all the time. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
- Original Message - From: Donley donley...@comcast.net To: Richard Knoppow 1oldle...@ix.netcom.com; k4...@mindspring.com; drakelist Drakelist@zerobeat.net Sent: Tuesday, July 12, 2011 8:05 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Completed tasks. Adjusted bias control until 0.5 VDC across cathode resistor, equals 33 mA, three resistors in parallel equals 100 mA total bias current. Bias voltage is -55 VDC at this point. No bias current measurement on plate current meter (actually has been just a slight wiggle all along, but nothing more than a half pointer width wiggle). C-73 is not a feedthrough, what point should be measured? My blunder (red face department) I just assumed the C version was pretty much the same as the plain TR-4 and looked at my enlarged schematics. Different amimal. Now to clarify what you see. When setting bias up with the controls as in the book you see nothing on the meter, maybe just a slight wiggle. When actually transmitting, either a CW or SSB signal you see the meter go up-scale and it peaks with the plat tuning adjustment. I presume it must also peak with the load adjustment although it may be all the way at one end. If this is the case I am sure you are seeing the RF output. The meter has a simple rectifier that samples some of the RF output and feeds the DC to the meter. Even though the spring may be intact and the switch seem good I would check the wiring at the meter switch (assuming its as accessible as on the TR-4). Use an external meter to see what is there. Its possible there is something shorting the switch or other wiring error there. Don't assume its OK because it look alright. The meter isn't working right something is wrong. To be blunt, if all the tube voltages are present and are about the right values, the problem just can not happen at the tube. IMO it isn't real, its an artifact of the meter switch or wiring being wrong. BTW, I think Garrey Barrell has a DVD for the model, if he does I URGE you to get it. When you do have the manuals printed out and bound at Kinko's or someplace. Also have the schematic printed out _large_ 18X24 or whatever the nearest standard size is. Get about three copies, they are not expensive. That way you can mark one of them up. Use colored pencils or highlighers to trace out the circuits. Drake schematics are dense although I've seen lots worse so some visual aid is necessary to be sure your eye doesn't skip onto the wrong line. Sometimes seemingly complicated circuits get a lot simpler when you trace them out, for one thing they are visually isolated. It may be helpful to re-draw some of the switches to have a better idea of what they do. GET THE DISC!!! -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Garey, I replaced the 6EV7 and there was no change. The plate voltage on the 6EV7 measures a little low at 230 VDC (supposed to 260). This makes the voltage on the relay lower than the 48 VDC (measures about 26 V if I remember correctly, but it seems to pull in okay). I measured the four voltages in all combinations of the sideband switch and the mode switch settings (sideband switch in non-X position and mode switch in SSB position and then in X-CW position). Then (sideband switch in X position and mode switch in SSB position and then X-CW position). The four plate voltage measurements were 687 to 690 VDC. The four screen voltage measurements were 230 to 236 VDC (a little low if 260 is correct). The four grid voltage measurements were around -60 VDC. When the Mode switch was in the SSB position, the cathode voltage was 156 VDC for each position of the sideband switch. When the Mode switch was in the X-CW position, the cathode voltage was 0.3 to 0.4 VDC. When I said I could adjust the bias voltage in the sideband X position, I didn't tell you that to do that I had to advance the transmitter gain control slightly to get 100 mA. But when I switched back to sideband non-X position, the current dropped to zero with no control by the bias knob on the AC-4. I have pulled the one relay and opened it and cleaned the contacts with no change. Also cleaned the contacts on the second relay. I have a power supply rebuild kit to install but the voltages appear to be okay and steady. I should probably order a new relay and try that. If I adjust the bias pot to get -60 VDC, I have no idea what the bias current is, but I get plenty of power out, around 200 watts, so it seems to work , I just can't measure the current. ?? Richard - Original Message - From: Garey Barrell k4...@mindspring.com To: Donley donley...@comcast.net Cc: Drakelist Drakelist@zerobeat.net Sent: Saturday, July 09, 2011 3:00 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I've thought about this some more this afternoon, and I think the next step is to measure the PA voltages with the switches set per the manual and see WHAT is missing. There aren't that many choices, ONE or more of the three are missing or incorrect. Plate +650 VDC Screen + 260 VDC Grid ~ -60 VDC Cathode ~ 0 VDC 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: My guess is that either a KEY is plugged in and open, or the 'shorting' jack, isn't! Try just inserting a phone plug into the KEY jack several times to see if that shorting contact will close as it should. Otherwise just insert a shorted phone plug into the KEY jack. Garey, Been there, did that. The key is not plugged in but the jack is shorted as it should be. When set up according to the manual, there is no bias current indicated on the meter when adjusting the bias control, but there is adjustable voltage (around -60 VDC +/- adjustable) on the PA grids. If I switch the sideband back to the X position, there is current indicated and I can easily vary it with the bias control and get 100 mA. What is the difference in being in the X sideband or opposite sideband position? Both are done with no transmitter gain and I get current in the X position and not in the other. Maybe there is an open condition on the sideband switch when it is in the non X position. Question - Is the bias current just plate current with no transmitter gain? Thanks. Richard kc9ub - Original Message - From: Garey Barrell k4...@mindspring.com To: Donley donley...@comcast.net Cc: Drakelist Drakelist@zerobeat.net Sent: Friday, July 08, 2011 11:18 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I'm not sure I follow your description below. 1. There is only ONE metering circuit, NO switching involved. If it can read PLATE current it can also read BIAS current. 2. 26 V across the relay sounds low, but if it pulls in that can be left til later. The manual says to switch the SIDEBAND switch counter-clockwise (the 'non-X' position) and the MODE switch to X-CW. I don't have a TR-4C set up at the moment, but I believe the KEY has to be closed. IF you have a key plugged in, it must be shorted. IF you do NOT have a key plugged in, there is a contact on the key jack that is 'supposed' to short the key. IF this contact does not MAKE properly you would see what I think you are describing. The goal here is to put the transceiver into TRANSMIT mode (X-CW) with the 'non' X SIDEBAND selected and the MIC GAIN at minimum. This should register the BIAS current of the PA stage since you're essentially in SSB with no audio applied, resulting in only the suppressed carrier and no PLATE current. My guess is that either a KEY is plugged in and open, or the 'shorting' jack, isn't! Try just inserting a phone plug into the KEY jack several times to see
Re: [Drakelist] TR-4C Bias Adjustment
Richard - Strange. We must be missing something obvious. IF there is Plate and Screen voltage applied to the tubes, and the Cathode is grounded, there WILL be Cathode current, regardless of anything else in the radio. This current will be whatever the power supply can put out until something breaks, either the tubes melt, or the fuse blows, or ... :-) This current is LIMITED by the BIAS voltage, with about -70V to cut off the current completely, and around -60V to limit it to 0.100A 'IDLE' current. Again, this is regardless of anything else in the radio. I think your problem is that the relay (which grounds the Cathodes) is not doing that with the MODE switch CCW, but appears to be with it set to X-CW. I don't see any relationship between the SSB 'Filter' switch and the keying system. It merely selects which of the two filters is in use, and controls the two lights indicating which sideband is selected. Have you subbed the 6EV7 tube? Can you hear the relay closing with the switches set for BIAS setting? The Cathodes are grounded by a single set of relay contacts, directly to chassis. Again, if the voltages are on the PA tubes and the Cathodes are grounded, the PA WILL draw current, regardless of anything else. I guess next is to check the PA voltages when the switches are set for BIAS setting per the manual. They can all be measured at the underchassis PA shield. The rearmost terminal is the Cathode lead and should be ~ 0 V when keyed, the next terminal forward is the Plate, (+650,) the fourth from the rear is the Screen, (+250). 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: My guess is that either a KEY is plugged in and open, or the 'shorting' jack, isn't! Try just inserting a phone plug into the KEY jack several times to see if that shorting contact will close as it should. Otherwise just insert a shorted phone plug into the KEY jack. Garey, Been there, did that. The key is not plugged in but the jack is shorted as it should be. When set up according to the manual, there is no bias current indicated on the meter when adjusting the bias control, but there is adjustable voltage (around -60 VDC +/- adjustable) on the PA grids. If I switch the sideband back to the X position, there is current indicated and I can easily vary it with the bias control and get 100 mA. What is the difference in being in the X sideband or opposite sideband position? Both are done with no transmitter gain and I get current in the X position and not in the other. Maybe there is an open condition on the sideband switch when it is in the non X position. Question - Is the bias current just plate current with no transmitter gain? Thanks. Richard kc9ub - Original Message - From: Garey Barrell k4...@mindspring.com To: Donley donley...@comcast.net Cc: Drakelist Drakelist@zerobeat.net Sent: Friday, July 08, 2011 11:18 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I'm not sure I follow your description below. 1. There is only ONE metering circuit, NO switching involved. If it can read PLATE current it can also read BIAS current. 2. 26 V across the relay sounds low, but if it pulls in that can be left til later. The manual says to switch the SIDEBAND switch counter-clockwise (the 'non-X' position) and the MODE switch to X-CW. I don't have a TR-4C set up at the moment, but I believe the KEY has to be closed. IF you have a key plugged in, it must be shorted. IF you do NOT have a key plugged in, there is a contact on the key jack that is 'supposed' to short the key. IF this contact does not MAKE properly you would see what I think you are describing. The goal here is to put the transceiver into TRANSMIT mode (X-CW) with the 'non' X SIDEBAND selected and the MIC GAIN at minimum. This should register the BIAS current of the PA stage since you're essentially in SSB with no audio applied, resulting in only the suppressed carrier and no PLATE current. My guess is that either a KEY is plugged in and open, or the 'shorting' jack, isn't! Try just inserting a phone plug into the KEY jack several times to see if that shorting contact will close as it should. Otherwise just insert a shorted phone plug into the KEY jack. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: A few weeks ago I started working on putting a TR-4C back on the air. I posed a question about the bias adjustment. I finally got back to working on the transceiver and still have some questions. I have followed all the information that has been sent to other people with bias problems, but that info has not helped me. My problem is that the bias current is not displayed or changed on the Plate Current meter when I adjust the bias control. I can measure and adjust the bias voltage on the final grids so
Re: [Drakelist] TR-4C Bias Adjustment
Richard - I've thought about this some more this afternoon, and I think the next step is to measure the PA voltages with the switches set per the manual and see WHAT is missing. There aren't that many choices, ONE or more of the three are missing or incorrect. Plate +650 VDC Screen + 260 VDC Grid ~ -60 VDC Cathode ~ 0 VDC 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: My guess is that either a KEY is plugged in and open, or the 'shorting' jack, isn't! Try just inserting a phone plug into the KEY jack several times to see if that shorting contact will close as it should. Otherwise just insert a shorted phone plug into the KEY jack. Garey, Been there, did that. The key is not plugged in but the jack is shorted as it should be. When set up according to the manual, there is no bias current indicated on the meter when adjusting the bias control, but there is adjustable voltage (around -60 VDC +/- adjustable) on the PA grids. If I switch the sideband back to the X position, there is current indicated and I can easily vary it with the bias control and get 100 mA. What is the difference in being in the X sideband or opposite sideband position? Both are done with no transmitter gain and I get current in the X position and not in the other. Maybe there is an open condition on the sideband switch when it is in the non X position. Question - Is the bias current just plate current with no transmitter gain? Thanks. Richard kc9ub - Original Message - From: Garey Barrell k4...@mindspring.com To: Donley donley...@comcast.net Cc: Drakelist Drakelist@zerobeat.net Sent: Friday, July 08, 2011 11:18 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I'm not sure I follow your description below. 1. There is only ONE metering circuit, NO switching involved. If it can read PLATE current it can also read BIAS current. 2. 26 V across the relay sounds low, but if it pulls in that can be left til later. The manual says to switch the SIDEBAND switch counter-clockwise (the 'non-X' position) and the MODE switch to X-CW. I don't have a TR-4C set up at the moment, but I believe the KEY has to be closed. IF you have a key plugged in, it must be shorted. IF you do NOT have a key plugged in, there is a contact on the key jack that is 'supposed' to short the key. IF this contact does not MAKE properly you would see what I think you are describing. The goal here is to put the transceiver into TRANSMIT mode (X-CW) with the 'non' X SIDEBAND selected and the MIC GAIN at minimum. This should register the BIAS current of the PA stage since you're essentially in SSB with no audio applied, resulting in only the suppressed carrier and no PLATE current. My guess is that either a KEY is plugged in and open, or the 'shorting' jack, isn't! Try just inserting a phone plug into the KEY jack several times to see if that shorting contact will close as it should. Otherwise just insert a shorted phone plug into the KEY jack. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: A few weeks ago I started working on putting a TR-4C back on the air. I posed a question about the bias adjustment. I finally got back to working on the transceiver and still have some questions. I have followed all the information that has been sent to other people with bias problems, but that info has not helped me. My problem is that the bias current is not displayed or changed on the Plate Current meter when I adjust the bias control. I can measure and adjust the bias voltage on the final grids so I know the system is working, I just can't measure the current. I have done most of the suggested things: loosen and retighten most ground screws, pulled and checked all tubes and used Deoxit on the pins and reinserted multiple times to clean the pins and sockets and cleaned the contacts on the relays. The 48 volt relay only has 26 volts on the pins, but it appears to pull in okay and work. Is 26 volts normal? Using the Drake manual instructions for bias adjust, no plate current reading is detected even though everything seems to be working. With the sideband switch in the clockwise position (opposite what the directions say) and transmitter gain full counterclockwise, I can adjust the plate current with the bias control. I also get full power output and can control the plate current with tuning and loading. It seems everything is fine except being able to measure the bias current with the recommended setup procedure. Any suggestions would be appreciated. 73 Richard kc9ub ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C Bias Adjustment
A few weeks ago I started working on putting a TR-4C back on the air. I posed a question about the bias adjustment. I finally got back to working on the transceiver and still have some questions. I have followed all the information that has been sent to other people with bias problems, but that info has not helped me. My problem is that the bias current is not displayed or changed on the Plate Current meter when I adjust the bias control. I can measure and adjust the bias voltage on the final grids so I know the system is working, I just can't measure the current. I have done most of the suggested things: loosen and retighten most ground screws, pulled and checked all tubes and used Deoxit on the pins and reinserted multiple times to clean the pins and sockets and cleaned the contacts on the relays. The 48 volt relay only has 26 volts on the pins, but it appears to pull in okay and work. Is 26 volts normal? Using the Drake manual instructions for bias adjust, no plate current reading is detected even though everything seems to be working. With the sideband switch in the clockwise position (opposite what the directions say) and transmitter gain full counterclockwise, I can adjust the plate current with the bias control. I also get full power output and can control the plate current with tuning and loading. It seems everything is fine except being able to measure the bias current with the recommended setup procedure. Any suggestions would be appreciated. 73 Richard kc9ub___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
Richard - I'm not sure I follow your description below. 1. There is only ONE metering circuit, NO switching involved. If it can read PLATE current it can also read BIAS current. 2. 26 V across the relay sounds low, but if it pulls in that can be left til later. The manual says to switch the SIDEBAND switch counter-clockwise (the 'non-X' position) and the MODE switch to X-CW. I don't have a TR-4C set up at the moment, but I believe the KEY has to be closed. IF you have a key plugged in, it must be shorted. IF you do NOT have a key plugged in, there is a contact on the key jack that is 'supposed' to short the key. IF this contact does not MAKE properly you would see what I think you are describing. The goal here is to put the transceiver into TRANSMIT mode (X-CW) with the 'non' X SIDEBAND selected and the MIC GAIN at minimum. This should register the BIAS current of the PA stage since you're essentially in SSB with no audio applied, resulting in only the suppressed carrier and no PLATE current. My guess is that either a KEY is plugged in and open, or the 'shorting' jack, isn't! Try just inserting a phone plug into the KEY jack several times to see if that shorting contact will close as it should. Otherwise just insert a shorted phone plug into the KEY jack. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: A few weeks ago I started working on putting a TR-4C back on the air. I posed a question about the bias adjustment. I finally got back to working on the transceiver and still have some questions. I have followed all the information that has been sent to other people with bias problems, but that info has not helped me. My problem is that the bias current is not displayed or changed on the Plate Current meter when I adjust the bias control. I can measure and adjust the bias voltage on the final grids so I know the system is working, I just can't measure the current. I have done most of the suggested things: loosen and retighten most ground screws, pulled and checked all tubes and used Deoxit on the pins and reinserted multiple times to clean the pins and sockets and cleaned the contacts on the relays. The 48 volt relay only has 26 volts on the pins, but it appears to pull in okay and work. Is 26 volts normal? Using the Drake manual instructions for bias adjust, no plate current reading is detected even though everything seems to be working. With the sideband switch in the clockwise position (opposite what the directions say) and transmitter gain full counterclockwise, I can adjust the plate current with the bias control. I also get full power output and can control the plate current with tuning and loading. It seems everything is fine except being able to measure the bias current with the recommended setup procedure. Any suggestions would be appreciated. 73 Richard kc9ub ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias Adjustment
My guess is that either a KEY is plugged in and open, or the 'shorting' jack, isn't! Try just inserting a phone plug into the KEY jack several times to see if that shorting contact will close as it should. Otherwise just insert a shorted phone plug into the KEY jack. Garey, Been there, did that. The key is not plugged in but the jack is shorted as it should be. When set up according to the manual, there is no bias current indicated on the meter when adjusting the bias control, but there is adjustable voltage (around -60 VDC +/- adjustable) on the PA grids. If I switch the sideband back to the X position, there is current indicated and I can easily vary it with the bias control and get 100 mA. What is the difference in being in the X sideband or opposite sideband position? Both are done with no transmitter gain and I get current in the X position and not in the other. Maybe there is an open condition on the sideband switch when it is in the non X position. Question - Is the bias current just plate current with no transmitter gain? Thanks. Richard kc9ub - Original Message - From: Garey Barrell k4...@mindspring.com To: Donley donley...@comcast.net Cc: Drakelist Drakelist@zerobeat.net Sent: Friday, July 08, 2011 11:18 PM Subject: Re: [Drakelist] TR-4C Bias Adjustment Richard - I'm not sure I follow your description below. 1. There is only ONE metering circuit, NO switching involved. If it can read PLATE current it can also read BIAS current. 2. 26 V across the relay sounds low, but if it pulls in that can be left til later. The manual says to switch the SIDEBAND switch counter-clockwise (the 'non-X' position) and the MODE switch to X-CW. I don't have a TR-4C set up at the moment, but I believe the KEY has to be closed. IF you have a key plugged in, it must be shorted. IF you do NOT have a key plugged in, there is a contact on the key jack that is 'supposed' to short the key. IF this contact does not MAKE properly you would see what I think you are describing. The goal here is to put the transceiver into TRANSMIT mode (X-CW) with the 'non' X SIDEBAND selected and the MIC GAIN at minimum. This should register the BIAS current of the PA stage since you're essentially in SSB with no audio applied, resulting in only the suppressed carrier and no PLATE current. My guess is that either a KEY is plugged in and open, or the 'shorting' jack, isn't! Try just inserting a phone plug into the KEY jack several times to see if that shorting contact will close as it should. Otherwise just insert a shorted phone plug into the KEY jack. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Donley wrote: A few weeks ago I started working on putting a TR-4C back on the air. I posed a question about the bias adjustment. I finally got back to working on the transceiver and still have some questions. I have followed all the information that has been sent to other people with bias problems, but that info has not helped me. My problem is that the bias current is not displayed or changed on the Plate Current meter when I adjust the bias control. I can measure and adjust the bias voltage on the final grids so I know the system is working, I just can't measure the current. I have done most of the suggested things: loosen and retighten most ground screws, pulled and checked all tubes and used Deoxit on the pins and reinserted multiple times to clean the pins and sockets and cleaned the contacts on the relays. The 48 volt relay only has 26 volts on the pins, but it appears to pull in okay and work. Is 26 volts normal? Using the Drake manual instructions for bias adjust, no plate current reading is detected even though everything seems to be working. With the sideband switch in the clockwise position (opposite what the directions say) and transmitter gain full counterclockwise, I can adjust the plate current with the bias control. I also get full power output and can control the plate current with tuning and loading. It seems everything is fine except being able to measure the bias current with the recommended setup procedure. Any suggestions would be appreciated. 73 Richard kc9ub ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C
I have pulled a TR-4C off the shelf, blown off a little dust and am trying to get it ready to put on the air. I know that I will have more questions but I want to start with the most important. When I try to adjust the bias current, I get no change in the current as I adjust the potentiometer. I think that it is working because I can tweak the bias pot when transmitting CW (dummy load) and the plate current changes indicating to me that the bias is changing. Am I correct in this assumption? Why doesn't the meter show the bias current? I have used another AC-4 with same result on the TR-4C, and I have used both AC-4's with the B and C line transmitters and the bias adjust works perfectly. Thanks. Richard kc9ub___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C Bias
I have a TR-4C that I cant set the bias on. When adjusting the bias control on the power supply it has no effect on the radio. I have 2 power supplies and both have no effect. I can remove the bottom cover from the supply and set the bias to the proper - voltage using my volt meter but it does not set the bias on the radio. Where do I start looking. Tnx in advance for the helpde Bill..KY4U PS. I have checked the cable from both supplies and the connector on the radio for loose connections but nothing wrong there.Bill___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias
Bill - I'm guessing here, since you didn't specify. Do you mean when you key the transceiver you have NO PLATE current, or LOTS of PLATE current??? Assuming you have NO PLATE current, which is most likely, consider that the PA tube normally want to draw as much current as possible when keyed, the BIAS is to LIMIT that current. If this is the case, then the transceiver PA is not really being keyed. Since you have eliminated the PS as the problem, there are only a couple of things to check. First, has the TR-4C been modified for use with TC-2 or TC-6? If it has, then there must be a jumper connected between two jacks on the upper rear panel to apply Screen voltage to the PA. IF not, then 'something' is open. IF the voltages on the PA tubes are correct, e.g., 650 VDC on plate caps, 260 VDC on Screen pins, and the Cathode is grounded, the PA WILL draw maximum current. Pin 3 of each final tube goes to a 15 ohm, 1W resistor. All three resistor leads then go to RFC2. The other lead of RFC2 connects to a ceramic feedthrough on the shield wall to R45. The other lead of R45 goes to a relay contact that is grounded in transmit. If this circuit is unbroken, including the relay contacts closing, and the Plate and Screen voltages are correct, the PA WILL draw current. Regardless of ANY other fault or problem in the transceiver. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Billy Loyd wrote: I have a TR-4C that I cant set the bias on. When adjusting the bias control on the power supply it has no effect on the radio. I have 2 power supplies and both have no effect. I can remove the bottom cover from the supply and set the bias to the proper - voltage using my volt meter but it does not set the bias on the radio. Where do I start looking. Tnx in advance for the helpde Bill..KY4U PS. I have checked the cable from both supplies and the connector on the radio for loose connections but nothing wrong there.Bill ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias
What does the PA current read with the RF gain at zero and the PTT switched to transmit? If it is high, then that might suggest an issue with the circuitry at the finals. Hard to guess if it is low and not adjustable. Curt KU8L Billy Loyd wrote: I have a TR-4C that I cant set the bias on. When adjusting the bias control on the power supply it has no effect on the radio. I have 2 power supplies and both have no effect. I can remove the bottom cover from the supply and set the bias to the proper - voltage using my volt meter but it does not set the bias on the radio. Where do I start looking. Tnx in advance for the helpde Bill..KY4U PS. I have checked the cable from both supplies and the connector on the radio for loose connections but nothing wrong there.Bill ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] tr-4c s-meter abnormality and reduced sensitivity
My TR-4C's s-meter points to S-9 under no signal condition. Adjusting the sensitivity and the zero pot won't correct it. I also noticed its reduced sensitivity compared to other Drakes that I have. The s-meter moves as expected when RF gain is lowered. Checked/replaced all tubes. I also checked the RF gain pot and it's fine. Resistances and voltages on the V13 12AX7 pins seem okay. I would appreciate any suggestions. Kihwal, K9SUL ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] tr-4c s-meter abnormality and reduced sensitivity
Kihwal - Check Pin 2 of V17 for resistance to ground (270 Ohms) and voltage ~7.5 VDC. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Kihwal Lee wrote: My TR-4C's s-meter points to S-9 under no signal condition. Adjusting the sensitivity and the zero pot won't correct it. I also noticed its reduced sensitivity compared to other Drakes that I have. The s-meter moves as expected when RF gain is lowered. Checked/replaced all tubes. I also checked the RF gain pot and it's fine. Resistances and voltages on the V13 12AX7 pins seem okay. I would appreciate any suggestions. Kihwal, K9SUL ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] tr-4c s-meter abnormality and reduced sensitivity
It's 290 ohm and the following are the voltage levels. pin1 0.2v pin2 12v pin5 237v pin6 246v Probably I should check the R's around the meter as the pin6 voltage seems a bit high. Any other suggestion? Thanks Kihwal K9SUL On Apr 14, 2011, at 2:29 PM, Garey Barrell k4...@mindspring.com wrote: Kihwal - Check Pin 2 of V17 for resistance to ground (270 Ohms) and voltage ~7.5 VDC. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Kihwal Lee wrote: My TR-4C's s-meter points to S-9 under no signal condition. Adjusting the sensitivity and the zero pot won't correct it. I also noticed its reduced sensitivity compared to other Drakes that I have. The s-meter moves as expected when RF gain is lowered. Checked/replaced all tubes. I also checked the RF gain pot and it's fine. Resistances and voltages on the V13 12AX7 pins seem okay. I would appreciate any suggestions. Kihwal, K9SUL ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] tr-4c s-meter abnormality and reduced sensitivity
Kihwal - OK. Most likely problem is a leaky C212. That Cathode (pin 1) voltage is way too high. the stage is drawing ~42 mA rather than the 28 mA it should be. Check R185, and disconnect C212. The Cathode voltage should drop to around 7.5 VDC. R92 is about 7% high, so in tolerance, but ... I suggest replacing R92 and C135 while you're in there! The Screen (pin 6) is also too high, but that may be a function of a damaged tube from overcurrent. It's possible that you are seeing AC ripple voltage if the Twist-Lok cap is original. You can check for AC voltage on Pin 6 with AF GAIN full CCW. If you read several volts AC here you'll need to replace C145. Replacements for the caps are available from www.hayseedhamfest.com. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Kihwal Lee wrote: It's 290 ohm and the following are the voltage levels. pin1 0.2v pin2 12v pin5 237v pin6 246v Probably I should check the R's around the meter as the pin6 voltage seems a bit high. Any other suggestion? Thanks Kihwal K9SUL On Apr 14, 2011, at 2:29 PM, Garey Barrellk4...@mindspring.com wrote: Kihwal - Check Pin 2 of V17 for resistance to ground (270 Ohms) and voltage ~7.5 VDC. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Kihwal Lee wrote: My TR-4C's s-meter points to S-9 under no signal condition. Adjusting the sensitivity and the zero pot won't correct it. I also noticed its reduced sensitivity compared to other Drakes that I have. The s-meter moves as expected when RF gain is lowered. Checked/replaced all tubes. I also checked the RF gain pot and it's fine. Resistances and voltages on the V13 12AX7 pins seem okay. I would appreciate any suggestions. Kihwal, K9SUL ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C Microphone
Hi group, My crysral element went bad in my old D-104. What would you recommend to replace it and have good transmit audio with my TR-4C. Thanks, Don ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Microphone
Hi Don, Some guy had a bunch of mic elements a short while ago on eBay that he claimed were replacements (albeit physically smaller) for the crystal cartridges inside the D-104... They were priced right, too, as I recall (a single digit)---but they looked like the old made-in-Japan-type of mic element that used to be a staple item at Radio Shack in days of yore, IMHO... ~73~ de Eddy VE3CUI - VE3XZ ** - Original Message - From: Don Miller To: drakelist@zerobeat.net Sent: Monday, February 28, 2011 1:38 PM Subject: [Drakelist] TR-4C Microphone Hi group, My crysral element went bad in my old D-104. What would you recommend to replace it and have good transmit audio with my TR-4C. Thanks, Don ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Microphone
Don, I use Shure 444D microphones with my Drakes and have always received good reports. Wyatt On Mon, Feb 28, 2011 at 12:38 PM, Don Miller k4...@hotmail.com wrote: Hi group, My crysral element went bad in my old D-104. What would you recommend to replace it and have good transmit audio with my TR-4C. Thanks, Don ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Microphone
I use a sure 444 and it works fine. My friend w2eny sells replacement mic elements for the d104 google him. George ne2i On Feb 28, 2011, at 1:38 PM, Don Miller k4...@hotmail.com wrote: Hi group, My crysral element went bad in my old D-104. What would you recommend to replace it and have good transmit audio with my TR-4C. Thanks, Don ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Repair
Dick - Congratulations! Always nice when one 'behaves' again :-) The TR-4C works a little differently in CW/TUNE than the T-4X(any). Essentially the Carrier Oscillator is shifted by about 800-900 kHz to put it within the passband of the LSB filter. A 750 ohm resistor (R72) is inserted in series with the Screen supply for the PA, limiting the Final plate current. The Balanced Modulator is unbalanced by a DC voltage derived from the XMTR GAIN control and the audio oscillator (V2) is fed to the SIDETONE VOX functions. The biggest difference is that the audio oscillator is NOT applied to the Balanced Modulator to generate the TUNE signal as in the T-4X(any). The Screen voltage to the PA is also reduced in the TUNE mode, but NOT in the CW mode. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com Dick KF4NS wrote: I DID IT ! I DID IT ! I DID IT! HAPPY DAYS ARE HERE AGAIN! Please excuse my slurred speech but I just finished a bottle of champagne. hi,hi ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C 1 meg resistor not connected?
Joe - If you check the schematic, you'll see that the resistor is a Test Point for adjusting the BAND oscillator per section 5-10 of the manual. So yes, it goes 'no where'! :-) 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com joe loverti wrote: Hello Drake List Members, I was doing some visual inspection of the bottom chassis of my TR-4C tonight and noticed an anomaly that I was hoping to get some guidance on. On pin 9 of tube V1 there is a 1meg resistor sticking up through a hole in the chassis (near the PNB-34 blanker circuit) that isn't connected to anything. The blanker IS installed on this radio. Does this resistor need to be connected to something or does this seems normal as is? Thanks in advance for your continued assistance! -Joe WS8X ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C 1 meg resistor not connected?
Hello Drake List Members, I was doing some visual inspection of the bottom chassis of my TR-4C tonight and noticed an anomaly that I was hoping to get some guidance on. On pin 9 of tube V1 there is a 1meg resistor sticking up through a hole in the chassis (near the PNB-34 blanker circuit) that isn't connected to anything. The blanker IS installed on this radio. Does this resistor need to be connected to something or does this seems normal as is? Thanks in advance for your continued assistance! -Joe WS8X ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C RCV / XVCR switch
Joe, If the switch has not been abused, cleaning the contacts should restore it to 100%. A little bit of Caig DeOxit followed by exercising the switch will probably remove any built up oxidation. The RF Output issue could be soft final tubes or the driver tube. Which band you're getting 65 W out? Is that is into a dummy load? How much output do you get on 80M vs 10M ? 73, Tom, AG9X On Tue, Sep 7, 2010 at 7:58 PM, Joe Loverti joelove...@gmail.com wrote: Hello Drake List Members, I have a TR-4C w/ a few gremlins I'm trying to iron out. Was hoping someone may be able to point me on the right direction. The RCVR / XCVR switch on the lower left-hand side of tbd chassis is bad. Does anyone know of a scource for a replacement? I have to hold the switch just so or else the RX goes deaf. Secondly, I'm only able to coax about 65W out on TX. I've been following the instructions on pg 5-8 in the original manual? I'm only getting about .2-.3 amperes of plate current once tuned up. The manual states I should be seeing around .4 ampreres. Any guidance would be much appriciated! Regards and 73, WS8X Joe ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C RCV / XVCR switch
Joe, On the TX power level. Check to make sure you have correct voltages on the AC4. Does the AC4 work well on another rig? Also have a look at your bias setting. Too much toward Class A lowers your output. Then of course check the output at 10M vs 80M. The tubes tend to soften earlier on higher frequencies, an easy way to tell the tubes are soft. Of course it could also be the 12BY7 driver, or alignment. Unless you think someone tuned up the alignment, I would try all the other items first. It still amazes me that these rigs hold their alignment so well for so many years. 73, Ron WD8SBB --- On Tue, 9/7/10, Joe Loverti joelove...@gmail.com wrote: From: Joe Loverti joelove...@gmail.com Subject: [Drakelist] TR-4C RCV / XVCR switch To: drakelist@zerobeat.net drakelist@zerobeat.net Date: Tuesday, September 7, 2010, 8:58 PM Hello Drake List Members, I have a TR-4C w/ a few gremlins I'm trying to iron out. Was hoping someone may be able to point me on the right direction. The RCVR / XCVR switch on the lower left-hand side of tbd chassis is bad. Does anyone know of a scource for a replacement? I have to hold the switch just so or else the RX goes deaf. Secondly, I'm only able to coax about 65W out on TX. I've been following the instructions on pg 5-8 in the original manual? I'm only getting about .2-.3 amperes of plate current once tuned up. The manual states I should be seeing around .4 ampreres. Any guidance would be much appriciated! Regards and 73, WS8X Joe ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C TX issue
Thanks Everyone for your responses and information. Mr. Frost, I just may want to buy one of those switches from you. Do you have any idea on a proper way to mount it? The original is riveted into the chassis, so I'm a little concerned about how the case will fit. As far as the tx is concerned. I am getting more output from the transmitter. I adjusted the power supply bias as per the manual .1 ampreres at idle. Last night I was able to get about 180-190 watts output on 80M into my MN-2000's watt meter. This was on my dummy load. After tune-up, the plate current was reading about .3 amperes. This seemed consistent with what the manual stated was within the normal range. I checked again today, (again on 80M) and noticed that the idle bias had drifted to where it was set last night. It was reading below . 1 amperes. I re-adjusted it back into specs and attempted to tune up the tx again into my D.L. I was able to get about 190W out one time. I attempted tune-up again and was only able to get about 100W out. I am noticing that I have to re-adjust the P.S. bias as it seems to be fluctuating. I tried tuning-up on 40M and the results were about the same in terms of tx output (about 100-120 watts). I've noticed that my load control has to be almost fully clockwise in order to get the max power out. Last night this was not the case. I was achieving nearly 200W out and the load control setting was only at 5. Not sure what is going on here. Any insight would be appreciated! Thanks and 73 with Regards. Joe; WS8X ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C RCV / XVCR switch
Hello Drake List Members, I have a TR-4C w/ a few gremlins I'm trying to iron out. Was hoping someone may be able to point me on the right direction. The RCVR / XCVR switch on the lower left-hand side of tbd chassis is bad. Does anyone know of a scource for a replacement? I have to hold the switch just so or else the RX goes deaf. Secondly, I'm only able to coax about 65W out on TX. I've been following the instructions on pg 5-8 in the original manual? I'm only getting about .2-.3 amperes of plate current once tuned up. The manual states I should be seeing around .4 ampreres. Any guidance would be much appriciated! Regards and 73, WS8X Joe ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C frequency instability
Loren - It's highly unlikely that BOTH PTOs would develop the jitters at the same time, so the problem is probably elsewhere. Does this occur on ALL bands, in particular both 80M and 40M for example? IF it appears on BOTH 80M and 40M, then my next suspect would be the contacts of relay K2. Does it appear on BOTH SSB and CW, or one or the other? V1, the Band Oscillator tube, would be the next suspect, IF the problem appears on 40M, but NOT on 80M or 20M. Lastly, how are you determining the instability? If you're listening to the Calibrator, confirm that it's NOT the Calibrator that is jittery! Let us know!! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com Loren McCullough wrote: What factors could contribute to frequency instability EXTERNAL to the PTO? My TR-4C has just developed a jittery frequency, jumping back and forth around center freq by as much as 50Hz. I know someone (if not many) will refer me to the excellent articles on PTO rebuilds, but before someone does, let me say that I have rebuilt my internal PTO last year and it has been working flawlessly since then. I believe this is external to the PTO because I am seeing the same instability on both the internal PTO (rebuilt last year as stated previously) and also on the RV-4C PTO (factory original, but has always been stable, other than a heat induced drift issue mentioned in another thread). Is this a Oscillator tube going bad, or some other component in the freq. chain? Thanks, Loren - WA3WZR ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C frequency instability
Hi Garey, I will have to try what you are suggesting and see if the instability is localized to 40m (where I am mostly), or is on the other bands. Will let you know. As to how I am determining it, I am mostly on digital modes (mainly PSK31) and I am seeing the jumps when viewing the digital signal traces on the computer display, as well as hearing the freq shifts (I'm a musician in my spare time, so I am well tuned to audio frequency changes). Thanks, Loren - WA3WZR On 6/2/2010 9:26 AM, Garey Barrell wrote: Loren - It's highly unlikely that BOTH PTOs would develop the jitters at the same time, so the problem is probably elsewhere. Does this occur on ALL bands, in particular both 80M and 40M for example? IF it appears on BOTH 80M and 40M, then my next suspect would be the contacts of relay K2. Does it appear on BOTH SSB and CW, or one or the other? V1, the Band Oscillator tube, would be the next suspect, IF the problem appears on 40M, but NOT on 80M or 20M. Lastly, how are you determining the instability? If you're listening to the Calibrator, confirm that it's NOT the Calibrator that is jittery! Let us know!! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com Loren McCullough wrote: What factors could contribute to frequency instability EXTERNAL to the PTO? My TR-4C has just developed a jittery frequency, jumping back and forth around center freq by as much as 50Hz. I know someone (if not many) will refer me to the excellent articles on PTO rebuilds, but before someone does, let me say that I have rebuilt my internal PTO last year and it has been working flawlessly since then. I believe this is external to the PTO because I am seeing the same instability on both the internal PTO (rebuilt last year as stated previously) and also on the RV-4C PTO (factory original, but has always been stable, other than a heat induced drift issue mentioned in another thread). Is this a Oscillator tube going bad, or some other component in the freq. chain? Thanks, Loren - WA3WZR ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.819 / Virus Database: 271.1.1/2912 - Release Date: 06/02/10 02:25:00 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C issues
just FYI, I took the TR-4C back to my work bench and looked it over again out of the case. Saw nothing, then I tried it on my spare AC4 (both AC4s have been rebuilt btw) and found no issues, took it back to the shack and tried it again and now all is functioning again. Have no idea. Still interested in a source for a replacement RFC13. Loren - WA3WZR ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C frequency instability
What factors could contribute to frequency instability EXTERNAL to the PTO? My TR-4C has just developed a jittery frequency, jumping back and forth around center freq by as much as 50Hz. I know someone (if not many) will refer me to the excellent articles on PTO rebuilds, but before someone does, let me say that I have rebuilt my internal PTO last year and it has been working flawlessly since then. I believe this is external to the PTO because I am seeing the same instability on both the internal PTO (rebuilt last year as stated previously) and also on the RV-4C PTO (factory original, but has always been stable, other than a heat induced drift issue mentioned in another thread). Is this a Oscillator tube going bad, or some other component in the freq. chain? Thanks, Loren - WA3WZR ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C issues
Was just putting my TR-4C back in service after having done some minor maintenance on it, now I am having some issues and need some assistance. Here are the symptoms: was tuning it up on 40m and could only get a maximum of about 80 watts out of it. I started going to different bands to check the output, on 80m I was getting about 150 watts out when the relay started oscillating in and out of transmit. Now it oscillates on all bands. Tried adjusting the vox controls and it does vary the oscillation, but not enough to stop it in the on position.. I don't have a spare 6EV7 for V19 (will have to get one on order), is this simply a VOX/RELAY problem, or should I be looking for something else? This TR-4C is s/n 39366. Also, is there a good source for the RF chokes? Thanks, Loren - WA3WZR ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C issues
Did you spray a lot of some sort of spray cleaner on the switch contacts and all over the tube socket pins? If you did, you could have set up leakage paths over insulation. Lee, w0vt - Original Message - From: Loren McCullough loren...@verizon.net To: drakelist Drakelist@zerobeat.net Sent: Sunday, May 30, 2010 9:59 PM Subject: [Drakelist] TR-4C issues Was just putting my TR-4C back in service after having done some minor maintenance on it, now I am having some issues and need some assistance. Here are the symptoms: was tuning it up on 40m and could only get a maximum of about 80 watts out of it. I started going to different bands to check the output, on 80m I was getting about 150 watts out when the relay started oscillating in and out of transmit. Now it oscillates on all bands. Tried adjusting the vox controls and it does vary the oscillation, but not enough to stop it in the on position.. I don't have a spare 6EV7 for V19 (will have to get one on order), is this simply a VOX/RELAY problem, or should I be looking for something else? This TR-4C is s/n 39366. Also, is there a good source for the RF chokes? Thanks, Loren - WA3WZR ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C issues
Why would you want to know about the chokes? There are more then one type in the radio. One is in the final plate lead or are you talking about the small ones or all of them? Is there more to this story? You need to give more information for help. Such as, how did it work prior to your cosmetic maintenance. If all you did was cosmetic stuff and it worked before you worked on it, I would suspect something simple such as the wrong tube in the wrong socket, or is the same tube in it's same socket? Lee, w0vt - Original Message - From: Loren McCullough To: LEE BAHR Cc: drakelist Sent: Sunday, May 30, 2010 10:11 PM Subject: Re: [Drakelist] TR-4C issues No, hasn't been cleaned like that in many years. I should mention the maintenance I was doing was cosmetic, not electrical/mechanical. Loren - WA3WZR On 5/30/2010 11:08 PM, LEE BAHR wrote: Did you spray a lot of some sort of spray cleaner on the switch contacts and all over the tube socket pins? If you did, you could have set up leakage paths over insulation. Lee, w0vt - Original Message - From: Loren McCullough loren...@verizon.net To: drakelist Drakelist@zerobeat.net Sent: Sunday, May 30, 2010 9:59 PM Subject: [Drakelist] TR-4C issues Was just putting my TR-4C back in service after having done some minor maintenance on it, now I am having some issues and need some assistance. Here are the symptoms: was tuning it up on 40m and could only get a maximum of about 80 watts out of it. I started going to different bands to check the output, on 80m I was getting about 150 watts out when the relay started oscillating in and out of transmit. Now it oscillates on all bands. Tried adjusting the vox controls and it does vary the oscillation, but not enough to stop it in the on position.. I don't have a spare 6EV7 for V19 (will have to get one on order), is this simply a VOX/RELAY problem, or should I be looking for something else? This TR-4C is s/n 39366. Also, is there a good source for the RF chokes? Thanks, Loren - WA3WZR ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.819 / Virus Database: 271.1.1/2906 - Release Date: 05/30/10 05:21:00 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C issues
The cosmetic stuff was for the case, needed a touch up on the paint on the case. Didn't touch any of the tubes or electronics, just pulled the case off and touched up the paint while I was also working on my RV-4C. Rig was working perfectly before I pulled it out of the shack. 180+ watts out on 40/80 and slightly less than that on the other bands. As to the RF choke, interested in RFC13 in particular. I have it patched together and just need to replace it one of these days. A lead broke when I was doing some relay maintenance about a year ago and I patched it together. Been running fine ever since, but thought I might get a replacement on hand in case I need one. Loren - WA3WZR On 5/30/2010 11:23 PM, LEE BAHR wrote: Why would you want to know about the chokes? There are more then one type in the radio. One is in the final plate lead or are you talking about the small ones or all of them? Is there more to this story? You need to give more information for help. Such as, how did it work prior to your cosmetic maintenance. If all you did was cosmetic stuff and it worked before you worked on it, I would suspect something simple such as the wrong tube in the wrong socket, or is the same tube in it's same socket? Lee, w0vt - Original Message - *From:* Loren McCullough mailto:loren...@verizon.net *To:* LEE BAHR mailto:pulsa...@embarqmail.com *Cc:* drakelist mailto:Drakelist@zerobeat.net *Sent:* Sunday, May 30, 2010 10:11 PM *Subject:* Re: [Drakelist] TR-4C issues No, hasn't been cleaned like that in many years. I should mention the maintenance I was doing was cosmetic, not electrical/mechanical. Loren - WA3WZR On 5/30/2010 11:08 PM, LEE BAHR wrote: Did you spray a lot of some sort of spray cleaner on the switch contacts and all over the tube socket pins? If you did, you could have set up leakage paths over insulation. Lee, w0vt - Original Message - From: Loren McCullough loren...@verizon.net To: drakelist Drakelist@zerobeat.net Sent: Sunday, May 30, 2010 9:59 PM Subject: [Drakelist] TR-4C issues Was just putting my TR-4C back in service after having done some minor maintenance on it, now I am having some issues and need some assistance. Here are the symptoms: was tuning it up on 40m and could only get a maximum of about 80 watts out of it. I started going to different bands to check the output, on 80m I was getting about 150 watts out when the relay started oscillating in and out of transmit. Now it oscillates on all bands. Tried adjusting the vox controls and it does vary the oscillation, but not enough to stop it in the on position.. I don't have a spare 6EV7 for V19 (will have to get one on order), is this simply a VOX/RELAY problem, or should I be looking for something else? This TR-4C is s/n 39366. Also, is there a good source for the RF chokes? Thanks, Loren - WA3WZR ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist No virus found in this incoming message. Checked by AVG -www.avg.com Version: 9.0.819 / Virus Database: 271.1.1/2906 - Release Date: 05/30/10 05:21:00 No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.819 / Virus Database: 271.1.1/2906 - Release Date: 05/30/10 05:21:00 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C tube shields
Even though I've had this TR-4C (#40249) about 2 years I've only just today took the top cover off for a look. I noticed that the metal shields are missing from V6 (12BY7A) driver and V12 (12BA6). Is this something I should be concerned about? Where, if anywhere, can I find replacement shields? Ken - N0VA___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C tube shields
Ken, Drake stopped installing tubes shields on those tubes a long time ago. The TR-4C never had them installed. 73, Gary W8PU http://home.roadrunner.com/~w8pu ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Keying Problem
Hi Paul: Regarding the fan. I have used fans on my A and B series and am installing in the TR's now. A standard 80mm square fan will fit perfectly on the back of the final cage. While you will get advice suggesting both directions of air, I think the best is to have it drawing air OUT of the cage. This way, it draws air from the entire interior of the rig. It is amazing how much cooler they run this way. I have used 12V fans but switched over to 24V but running on 12V so they are quieter. Search thru Jameco or MCM or Mouser or Digikey etc to find the quietest, highest flow 80mm fan. On the TR4 and Tx4A,B, the holes in the cage exactly lined up with mounting holes in the fans so no holes were ever drilled. I U can use some small nylon thread inserts to mount. I have also used foam mounting tape strips and this works just fine and is very quiet. For power, use the 12Vac filament lines--I use a bridge diode rectifier assy and a 100mFd 25-35V cap. and snake the wires out without drilling any new holes. I'm sure others will chime in on this as well..this has been my experience. Keep em glowin Curt KU8L Paul Strickland wrote: I acquired this TR-4C from my father a decade ago, W9LKZ (SK). I've rebuild the power supply with great success a few years ago. Now I have a problem with the xmtr keying circuit. After allowing the rig to warm up for half an hour or so when I key the mic and then release it the transmitter section remains in the transmit mode. Not a whole lot of fun... I also found this 4 section cap # C145. Where can I find a replacement for this device. I love these old glow in the dark rigs, also keeps the shack warm in the winter. I have also seen/heard of a mod to put a fan over the final amp cage. What voltage is being used to power the fan and how big of a fan? Thanks for all the other good info I've gleaned from this site Paul Strickland WB9SUG ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Keying Problem
C-145 is under attack on general principles of age. The birth certificate shows the date of September 21, 1973. This device needs to be replaced before it causes all sorts of problems. A gassy tube had crossed my mind but this one still glows a nice warm orange. Past experience is that a gassy tube will take on a slightly blue tint around the edges. R106 sorta slipped under my radar. Forgot that these resistors used Fullers Earth that dries out over time. Not like these new thin/thick etched film ones we have today. Thanks for the ideas. I will get into these and check them out. More Later as progress to healing this ol' girl goes on. 73's Paul Strickland WB9SUG___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Keying Problem
Paul - Gassy tubes don't always glow blue.. When enough cathode material deposits itself on the grid, the grid begins to emit electrons, causing the grid to go more positive. Called gassy, but really grid emission. End result is when the grid gets hot enough to emit, the grid goes more positive, and is no longer able to cut off plate current with a given bias applied. Typically happens when a tube is turned on hard, then when the normal cutoff bias tries to turn it off, there's not enough bias and it stays on. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com Paul Strickland wrote: C-145 is under attack on general principles of age. The birth certificate shows the date of September 21, 1973. This device needs to be replaced before it causes all sorts of problems. A gassy tube had crossed my mind but this one still glows a nice warm orange. Past experience is that a gassy tube will take on a slightly blue tint around the edges. R106 sorta slipped under my radar. Forgot that these resistors used Fullers Earth that dries out over time. Not like these new thin/thick etched film ones we have today. Thanks for the ideas. I will get into these and check them out. More Later as progress to healing this ol' girl goes on. 73's Paul Strickland WB9SUG ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C Keying Problem
I acquired this TR-4C from my father a decade ago, W9LKZ (SK). I've rebuild the power supply with great success a few years ago. Now I have a problem with the xmtr keying circuit. After allowing the rig to warm up for half an hour or so when I key the mic and then release it the transmitter section remains in the transmit mode. Not a whole lot of fun... I also found this 4 section cap # C145. Where can I find a replacement for this device. I love these old glow in the dark rigs, also keeps the shack warm in the winter. I have also seen/heard of a mod to put a fan over the final amp cage. What voltage is being used to power the fan and how big of a fan? Thanks for all the other good info I've gleaned from this site Paul Strickland WB9SUG ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Keying Problem
Paul, Go to www.hayseedhamfest.com and check Tom's site. I think he is out of the TR4C caps right now, but is tooling up to produce all the parts in house and will be back on line soon. You might get on the list, hi. He builds VERY high quality multiple capacitor cans and has reasonable prices, in my opinion. No commercial interest in his business, but am one of his happy customers with several cans sitting here that I got from him and more on the way, hi. 73, Don, WB5HAK - Original Message - From: Paul Strickland To: drakelist@zerobeat.net Sent: Monday, January 25, 2010 9:59 PM Subject: [Drakelist] TR-4C Keying Problem I acquired this TR-4C from my father a decade ago, W9LKZ (SK). I've rebuild the power supply with great success a few years ago. Now I have a problem with the xmtr keying circuit. After allowing the rig to warm up for half an hour or so when I key the mic and then release it the transmitter section remains in the transmit mode. Not a whole lot of fun... I also found this 4 section cap # C145. Where can I find a replacement for this device. I love these old glow in the dark rigs, also keeps the shack warm in the winter. I have also seen/heard of a mod to put a fan over the final amp cage. What voltage is being used to power the fan and how big of a fan? Thanks for all the other good info I've gleaned from this site Paul Strickland WB9SUG -- ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist -- No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.432 / Virus Database: 271.1.1/2645 - Release Date: 01/25/10 19:36:00 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
