Re: [Drakelist] Drake 2-B S-Meter Calibration/AVC
Garey and Dennis, thanks agian for the inputs. Regarding tubes, I have replaced those afected by AVC/1 and AVC/2. Nothing changed. Maybe I will need to try to redo this based on what Garey wrote. I will get special attention to the 6BA6 which is driven by AVC/1. These are some effects that I would like to line up and make sure you have the details - After 10-15 minutes Smeter goes to S1. If I turn the radio off and on it will do again, but journey is shorter. The S-meter will come from S4 to S1 in 5-6 minutes. - During the journey to S1, after start up, if I am in Fast AVC and switch to Slow (introducing the 1uf capacitor), the S meter's needle deeps to the left and gets up again. I hear the RX background noise to pulse too. It does that once. - In any circusntance there is a slight S meter difference when I switch from SAVC to FastAVC and vice-versa. In SAVC it reads about half S unit more (to the right). - I have realized that when th BFO is on, the S-Meter moves a bit do the left. Normally I would answer to someone that would have posted something similar to it that the AVC discharge path is malfunctioning. I have checked the resistors in this path. I have also checked the time constant capacitor in the AV/2 and AV/1 circuits. I will have time to check spurios oscillation and/or grid leak whan I get back home. I will be away until year's eve or so. Please send any ideas that are very much welcome. Best regards Fred On Fri, 26 Dec 2008 04:19:24 -0200, Garey Barrell k4...@mindspring.com wrote: Fred - I have been traveling and missed some of this thread. Try subbing tubes in the AVC stages. Often an IF tube will be gassy, and the grid will lose control after 5-20 minutes of warmup. The 12BA6 is particularly susceptible to this problem, even in New Old Stock tubes. You sometimes have to try three or four before finding a good one. The AVC circuit is so hi-z that it takes very little grid current to upset it. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com py...@integral.com.br wrote: Dennis, merry xmas to you and yours, firts of all. Thanks for the input. I don not know if I my explanation was clear enough. The long S-meter journey to S1 just occurs after power the unit up and for 10 or so minutes. After that the behaivor is normal. Yes my first shot was a opened path to discharge the AVC circuitry. Unfortunately I have not found anything to blame. Did you consider that after the initial pb the behaivor seems to be normal ? Regards Fred ___ 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] t4x case type
i need to start saving the trivia facts. this same question has been asked many times over i am sure. thanks On Fri, Dec 26, 2008 at 12:22 AM, Garey Barrell k4...@mindspring.comwrote: Carey - In my experience, Drake started using a spatter finish on the version 3 of the R-4A, which was well into the T-4X production. Early T-4X were indeed smooth satin black finish, as were the R-4 and R-4A version 1 and 2. The spatter finish went through the R-4B and then the textured finish started with the C-Line. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com Carey Lockhart wrote: hi gang and merry christmas does the t-4x have the splatter paint job or a smooth paint on the case? Carey Lockhart, KC5GTT kc5...@gmail.com mailto:kc5...@gmail.com www.kc5gtt.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist -- Carey Lockhart, KC5GTT Boerne, Tx. 78006 www.kc5gtt.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] t4x case type
On Dec 25, 2008, at 7:57 PM12/25/08, Carey Lockhart wrote: hi gang and merry christmas does the t-4x have the splatter paint job or a smooth paint on the case? Mine has smooth paint... Tom WA8PYR ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR3
John - OK. Well, there is definitely something awry (love that word! :-) ), on the decoupled (+245V) bus. The FIRST suspect in any electronic equipment is the electrolytic capacitors, since they are the least reliable component in any piece of equipment over a couple of years old. They ain't particularly reliable even in brand new stuff, ref the stolen electrolyte formula from a few years ago! As you can see from the schematic I sent you, the only two stages on that bus are V16 and V18. Something is also wrong with your readings of the two voltages, since if you were REALLY dropping 117 V across that poor little 3300 ohm, 1/2W resistor, it would be trying to dissipate over 4W, enough to smoke it pretty quickly. So the first order of business is to find out why that voltage appears to be 137V, which it clearly cannot be! So On the other hand, a low voltage here could at least potentially be a cause of your audio distortion situation. A couple of suspects would be the coupling capacitor (C134) to the AF Output stage, V17, and/or the cathode bypass of this stage, C135. A check of R92, cathode resistor of V17 would also be indicated. A problem here is also going to affect your S-Meter, since V17 is one leg of the S-Meter bridge. There are only three resistors that come off of that +245V bus, all high value (220k - 330k). I would start at this point to make voltage measurements on these three tubes to see if we can get a handle on where that voltage is really going. The added 100 ohm resistor in the AF pot / grid circuit is there because someone suspected an RF oscillation in the AF section. It's called a squeal stopper, and while almost certainly not a problem, will do absolutely no harm. The circuit impedance here is very high, and that 100 ohms look like a piece of wire to the desired signals that should be at that point. Yeah, once you get elbow deep into a troubleshooting problem, it's best to fight through it. If you leave it for another, you lose your place and essentially have to start over! I believe your current symptoms are all related, and indicate a single cause, although that cause may be the result of more than one faulty component. I consider Al a good friend, although we have only met a few times in person at Shelby. I used to go every year when I lived in Atlanta, but haven't been in the last couple of years. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com John King wrote: Thanks Garey. I installed R 111 as I remembered it was when I removed it and the TR 3 is receiving. The other early TR3s that I was sent sent pictures of (of the two boards and resistor between then) were wired differently and the incorrect placement of the resistor was causing the smoke. Voltage measurement shows the voltage on one end of R111 to be 254 bolts and on the other endvolts. Sounds LOW on thevolt end. But I am not sure. Upon putting the TR 3 on an antenna and comparing it the the TR 4 as far as sensitivity according to the ear, meter readings, and sound of the audio, I find the following: 1. The TR 4 S meter, while using the same antenna and same SSB signal tuned in, shows about 3 S units more on the S meter. 2. The receive audio on the TR3 sounds MUCH hotter and is loud with the AF gain pot at about 7:30. 3. I notice some distortion when the AF gain pot is raised to provide more than audio necessary for what I consider comfortable listening. 4 I note that the S meter on the TR3 doesn't appear to react in quite the same manner as the TR4 in that it doesn't respond as to signal level changes. (May be my imagination) 5. I also note that someone has added, what appears to be an after market 100 ohm resistor from the center of the AF pot in series with the wire that would normally attach to the center of the pot (rear ganged pot). I hope to get started on the transmitter section SOON!! Garey, words cannot express the appreciation I feel for your assistance. You are so very helpful and assist guys, like me, who don't really enjoy such trouble shooting challenges. When I get a rig going, I feel pride but I can't say I enjoy the frustrations. I probably have over 100 receivers and transmitters made by Collins, Drake, Hallicrafters, National Hammarlund, RME, Heath Elmac, Morrow, WRL Globe, Military and homebrew and if I don't get on a piece of gear and STAY on it until it is repaired, I will never get it working. If I walk away from a piece of gear, and move to another, I will have to start over when I return to it. I have a Hammarlund HX 500 transmitter with what appears to be a parasitic problem in the low level misers that puts a fuzz (not ac hum) on the signal and have been working on it off and on for about five years but haven't found the cause. That is because I become frustrated and walk away and
Re: [Drakelist] NEW twist
John - New twist, but still same basic problem. Voltage checks, V16, V17 and V18! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com John King wrote: Well this morning, I turn the TR3 on and guess what: antenna connected, turn switch on and S meter rises to 40 db over 9 and stays there.doesn't return to S1 and slight HUM from speaker with no audible signals.not even Crystal calibrator. I forgot to mention in my prior email that the S meter, at turn on, was only rising to S 5 before returning to S 1. Now it rises to 40 over and stays there..another Queer electron invades 73, John, K5PGW No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.176 / Virus Database: 270.10.0/1864 - Release Date: 12/25/2008 9:40 AM ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] plug in relay for TR-4C
The relay in my TR-4C is indeed has a 2.5K coil but the resistor in series with the coil is 27 ohms @1/2 watt. It is R192. Lee, w0vt ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] plug in relay for TR-4C
Lee - R192 is not in series with the relay coil It is a fuse resistor in the +250V bus, and first appeared in the Version 9 TR-4C. The 2.5k relay didn't show up until Version 12, at s/n 42500, and the series resistor is R194. It's does not have the 1W designation on the schematic, but the ones I have seen that were factory installed were indeed 1W resistors. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com LEE BAHR wrote: The relay in my TR-4C is indeed has a 2.5K coil but the resistor in series with the coil is 27 ohms @1/2 watt. It is R192. Lee, w0vt ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Drake 2-B S-Meter Calibration/AVC
The minor changes to S-meter reading (transient or otherwise) as you introduce or remove AVC path components (Fast vs Slow and BFO) don't seem very revealing to me. The slow drift in the S-meter over several minutes is the revealing symptom. This latter behavior could be caused by a gassy tube whose grid is being fed from that very high impedance AVC line as Garey has suggested or by the grid having become contaminated and thus acting as a virtual cathode. So swapping out all those gain-control tubes with a fresh tube one at a time would be a good experiment. Dennis AE6C On Fri, Dec 26, 2008 at 3:26 AM, py...@integral.com.br wrote: Garey and Dennis, thanks agian for the inputs. Regarding tubes, I have replaced those afected by AVC/1 and AVC/2. Nothing changed. Maybe I will need to try to redo this based on what Garey wrote. I will get special attention to the 6BA6 which is driven by AVC/1. These are some effects that I would like to line up and make sure you have the details - After 10-15 minutes Smeter goes to S1. If I turn the radio off and on it will do again, but journey is shorter. The S-meter will come from S4 to S1 in 5-6 minutes. - During the journey to S1, after start up, if I am in Fast AVC and switch to Slow (introducing the 1uf capacitor), the S meter's needle deeps to the left and gets up again. I hear the RX background noise to pulse too. It does that once. - In any circusntance there is a slight S meter difference when I switch from SAVC to FastAVC and vice-versa. In SAVC it reads about half S unit more (to the right). - I have realized that when th BFO is on, the S-Meter moves a bit do the left. Normally I would answer to someone that would have posted something similar to it that the AVC discharge path is malfunctioning. I have checked the resistors in this path. I have also checked the time constant capacitor in the AV/2 and AV/1 circuits. I will have time to check spurios oscillation and/or grid leak whan I get back home. I will be away until year's eve or so. Please send any ideas that are very much welcome. Best regards Fred On Fri, 26 Dec 2008 04:19:24 -0200, Garey Barrell k4...@mindspring.com wrote: Fred - I have been traveling and missed some of this thread. Try subbing tubes in the AVC stages. Often an IF tube will be gassy, and the grid will lose control after 5-20 minutes of warmup. The 12BA6 is particularly susceptible to this problem, even in New Old Stock tubes. You sometimes have to try three or four before finding a good one. The AVC circuit is so hi-z that it takes very little grid current to upset it. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com py...@integral.com.br wrote: Dennis, merry xmas to you and yours, firts of all. Thanks for the input. I don not know if I my explanation was clear enough. The long S-meter journey to S1 just occurs after power the unit up and for 10 or so minutes. After that the behaivor is normal. Yes my first shot was a opened path to discharge the AVC circuitry. Unfortunately I have not found anything to blame. Did you consider that after the initial pb the behaivor seems to be normal ? Regards Fred ___ 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] t4x case type
A correction to my earlier post. My early R4-B has the spattered not the textured finish. This is consistent with Garey's statement on the crossover point from smooth to textured. Dennis AE6C On Thu, Dec 25, 2008 at 7:21 PM, Dennis Monticelli dennis.montice...@gmail.com wrote: My early R4B is textured. On Thu, Dec 25, 2008 at 5:46 PM, Carey Lockhart kc5...@gmail.com wrote: well i think i will go with the smooth since thats what it is. i can always repaint later. my b line has textured paint but my older tr-4 does not. thanks for the help guys Carey Lockhart, KC5GTT kc5...@gmail.com www.kc5gtt.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
[Drakelist] TR4-CW Question
I continue to restore my TR4-CW/RIT, serial number 44xxx. So far everything is falling in place, except AM receive is dead. V2 is the the AM detector and first audio amp. According to the late schematic, the cathode (pin 2) is connected to a 0.001 cap that floats in the SSB mode and is grounded in the CW-X and AM-X modes. However, in my rig, pin 2 has both a 0.001 and 0.01 caps to ground, and placing the mode switch to AM-X grounds pin 2, thus bypassing both caps. Which is correct, the schematic or the rig? Thanks in advance. 73 Lee WB6SSW **One site keeps you connected to all your email: AOL Mail, Gmail, and Yahoo Mail. Try it now. (http://www.aol.com/?optin=new-dpicid=aolcom40vanityncid=emlcntaolcom0025) ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR4-CW Question
Lee - Looking at the 42500 schematic, it looks to me like the cathode of V2 has NO DC return in position X-CW or X-AM because of C225 !! Circuit in previous schematic (38800) is identical, except no C225, and the DC return is via R65 up by V13B. Without C225, the cathode of V2 is grounded via the switch and the X relay, K2. WITH C225 as drawn, the cathode of V2 has no DC return in ANY mode. The stage can't work without a DC return for the cathode of V2. In CAL, the cathode of V2 is floating and the cathodes of V16 and V5 are grounded. In SSB, the cathode of V2 is floating, cutting off the sidetone and the cathode of V16 is grounded, enabling the PD. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com leecra...@aol.com wrote: I continue to restore my TR4-CW/RIT, serial number 44xxx. So far everything is falling in place, except AM receive is dead. V2 is the the AM detector and first audio amp. According to the late schematic, the cathode (pin 2) is connected to a 0.001 cap that floats in the SSB mode and is grounded in the CW-X and AM-X modes. However, in my rig, pin 2 has both a 0.001 and 0.01 caps to ground, and placing the mode switch to AM-X grounds pin 2, thus bypassing both caps. Which is correct, the schematic or the rig? Thanks in advance. 73 Lee WB6SSW ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
