[Drakelist] R4B xtal filter bandwidth problem
Folks Does anyone have experience of the R4B as-fitted xtal fliter showing a -3dB bandwidth of just 250Hz, from 5644.910 to 5644.660kHz This suggests to me that only one crystal is in circuit, but I do not have the circuit of what is in the can so I can be sure. Is there a circuit available? Before I dismantle, suggestions welcome as to any other diagnostics I can do. many thanks 73s, Gwyn Griffiths G3ZIL ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] R4B xtal filter bandwidth problem
Gwyn, Are you really meaning a R4B? I am fairly sure that the B series RX has an LC circuit in the 60Khz range for its selectivity. I didn't think the RX had xtal filters till the C series. 73, Ron WD8SBB --- On Sun, 7/18/10, Griffiths G. g.griffi...@noc.soton.ac.uk wrote: From: Griffiths G. g.griffi...@noc.soton.ac.uk Subject: [Drakelist] R4B xtal filter bandwidth problem To: drakelist@zerobeat.net drakelist@zerobeat.net Date: Sunday, July 18, 2010, 4:47 AM Folks Does anyone have experience of the R4B as-fitted xtal fliter showing a -3dB bandwidth of just 250Hz, from 5644.910 to 5644.660kHz This suggests to me that only one crystal is in circuit, but I do not have the circuit of what is in the can so I can be sure. Is there a circuit available? Before I dismantle, suggestions welcome as to any other diagnostics I can do. many thanks 73s, Gwyn Griffiths G3ZIL ___ 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] R4B xtal filter bandwidth problem
Ron The R4B does have a roofing xtal filter at the first IF. But you are right, in that the main selectivity (at four switched bandwidths) is at the second IF at 50kHz with LC filters. The problem here is that at the input to the second mixer grid, the bandwidth is only 250Hz after the supposed roofing filter. 73s Gwyn From: Ron [wd8...@yahoo.com] Sent: 18 July 2010 11:39 To: drakelist@zerobeat.net; Griffiths G. Subject: Re: [Drakelist] R4B xtal filter bandwidth problem Gwyn, Are you really meaning a R4B? I am fairly sure that the B series RX has an LC circuit in the 60Khz range for its selectivity. I didn't think the RX had xtal filters till the C series. 73, Ron WD8SBB --- On Sun, 7/18/10, Griffiths G. g.griffi...@noc.soton.ac.uk wrote: From: Griffiths G. g.griffi...@noc.soton.ac.uk Subject: [Drakelist] R4B xtal filter bandwidth problem To: drakelist@zerobeat.net drakelist@zerobeat.net Date: Sunday, July 18, 2010, 4:47 AM Folks Does anyone have experience of the R4B as-fitted xtal fliter showing a -3dB bandwidth of just 250Hz, from 5644.910 to 5644.660kHz This suggests to me that only one crystal is in circuit, but I do not have the circuit of what is in the can so I can be sure. Is there a circuit available? Before I dismantle, suggestions welcome as to any other diagnostics I can do. many thanks 73s, Gwyn Griffiths G3ZIL ___ Drakelist mailing list Drakelist@zerobeat.net/mc/compose?to=drakel...@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist -- This message has been scanned for viruses and dangerous content by MailScannerhttp://www.mailscanner.info/, and is believed to be clean. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] R4B xtal filter bandwidth problem
Gwyn - Certainly sounds like a bad filter. Can't say I've ever seen or heard of one failing that way. Seems highly unlikely. I'd start by just connecting a wire between the leads going to the input and output of the filter, after disconnecting them from the filter itself. The filter is most likely just a series of four (it's a four pole filter) crystals connected in series with small caps to ground between them. It's a little hard to imagine THREE crystals all failing or coming 'unglued' at the same time. I assume this was a catastrophic failure. Does the receiver still seem about the same sensitivity, just restricted? Let us know what you find! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com Griffiths G. wrote: Folks Does anyone have experience of the R4B as-fitted xtal fliter showing a -3dB bandwidth of just 250Hz, from 5644.910 to 5644.660kHz This suggests to me that only one crystal is in circuit, but I do not have the circuit of what is in the can so I can be sure. Is there a circuit available? Before I dismantle, suggestions welcome as to any other diagnostics I can do. many thanks 73s, Gwyn Griffiths G3ZIL ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Fan on R4B and linears
I can endorse the Panasonic Panaflo series. It is not only a quality fan, it is relatively quiet. Dennis AE6C On Sat, Jul 17, 2010 at 7:55 AM, Jim Shorney jshor...@inebraska.com wrote: On Sat, 17 Jul 2010 09:16:50 -0500, Don Cunningham wrote: Evan, Would you share the make and model of the fans that work so well for you?? Sounds like something I need to do here. Well, I'm not Evan, but I will share what I am doing with my L-4PS. The larger the fan, the slower (and quieter) it needs to run to move a certain amount of air. Or, the more volume it will move for a given speed. I have a pair of ebm-papst 12 volt fans pulled from server computers, model 4412 F / 2M. They are about 4.75 inches (120mm) in size, and I run the two in series from a 12 volt power source, pulling air OUT on top of the PS. They seem to work very well, and I can't hear them running when I am sitting practically right on top of the PS. I have to check with my hand to feel the air to make sure they are running. They can be mounted as Evan describes, or some thin stick-on weather stripping material can be cut into small strips and affixed to the fans. I currently have mine just sitting there with nothing between the fan and the PS, they are so lightweight and made of plastic that they don't scuff. What is probably more important here than the type of fan is the quality. Avoid cheap sleeve-bearing PC fans like the plague, they will die on you. Guaranteed. The ebm-papst seem to be a decent product. Panasonic Panaflo fans are excellent, they seem to go forever. Be cautious of PC fans labeled as ball bearing, some of the small ones that I have taken apart have a ball bearing at one end of the impeller shaft, and a sleeve bearing at the other. I don't see this as an improvement. The new Sunon Maglev design looks interesting and seems to have better longevity, but they haven't been around long enough to make an accurate judgement. And remember to clean the blades once in a while, a little dust can reduce the airflow by a surprising amount. I'm sure Evan will have some great recommendations as well! 73 -Jim -- Ham Radio NU0C Lincoln, Nebraska, U.S.S.A. TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time! Give a man a URL, and he will learn for an hour; teach him to Google, and he will learn for a lifetime. HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/ http://radiojim.exofire.net http://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org ___ 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] R4B xtal filter bandwidth problem
Garey - Many thanks. Linking across the (disconnected) filter brings the bandwidth to what one would expect with just the IFTs at first IF. The selectivity is then properly controlled at the bandpass LC filter as it should be. I removed T6, the xtal filter can. There are only two xtals in a simple half lattice configuration (marked 5645 and 5642kHz), no internal capacitors, and the matching transformer at the output is not quite as in the circuit in the manual I have. There it is shown as an autotransformer, in reality it has two windings, the common output of the two xtals being to the hot end of the low impedance primary winding at the earthy end of the secondary. Hence, electrically, virtually no different to the circuit. Out of the receiver, the filter tests OK with a sig gen, the two xtals working, no sign of a problem, with series resonance at 5644.7 and 5641.0kHz. So the next test when I have a workshop session will be on T5 secondary, perhaps the secondary connected to the 5642kHz xtal has a problem. By the way, the receiver is about 40dB low on sensitivity as well (I bought it that way earlier this year - in need of a challenge!). So far, I have the RF amplifier documented, but ideally would be good to compare to a fully working set. T1 has a measured Q of 60 at 3.6MHz, and a step up of about 2.5. gm of the 6BZ6 at the bias point is about 2mA/V, and with the calculated dynamic impedance of T2 at 3.6MHz of 4500 ohms, the stage gain is theoretically 9, though I measure 7, so not far off. I intend to go through like this, stage by stage, as I've yet to find whether this level of detail is already available. 73 Gwyn G3ZIL From: drakelist-boun...@zerobeat.net [drakelist-boun...@zerobeat.net] On Behalf Of Garey Barrell [k4...@mindspring.com] Sent: 18 July 2010 14:46 To: drakelist Subject: Re: [Drakelist] R4B xtal filter bandwidth problem Gwyn - Certainly sounds like a bad filter. Can't say I've ever seen or heard of one failing that way. Seems highly unlikely. I'd start by just connecting a wire between the leads going to the input and output of the filter, after disconnecting them from the filter itself. The filter is most likely just a series of four (it's a four pole filter) crystals connected in series with small caps to ground between them. It's a little hard to imagine THREE crystals all failing or coming 'unglued' at the same time. I assume this was a catastrophic failure. Does the receiver still seem about the same sensitivity, just restricted? Let us know what you find! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com Griffiths G. wrote: Folks Does anyone have experience of the R4B as-fitted xtal fliter showing a -3dB bandwidth of just 250Hz, from 5644.910 to 5644.660kHz This suggests to me that only one crystal is in circuit, but I do not have the circuit of what is in the can so I can be sure. Is there a circuit available? Before I dismantle, suggestions welcome as to any other diagnostics I can do. many thanks 73s, Gwyn Griffiths G3ZIL ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] R4B xtal filter bandwidth problem
Gwyn - Very interesting. I've been fortunate to avoid this sort of problem in almost 50 years of working on Drake gear! :-) I would suspect T5 at this point as well because it's about the only other thing around! I assume you have subbed a 12BE6, a 'shaky' tube at best. I HAVE seen transformers like T5 'partially' fail due to a Screen-Suppressor short in V2, sometimes burning R9 in the process. The excess current damages the insulation on the winding, causing shorted turn(s). The 'repairman' replaces the tube, and fried resistor, and when that doesn't fix it, sells it as 'working perfectly' :-) It's possible your low sensitivity is related to damage in T5 as well. The only information I have that might be useful is to expect ~1.5 to 2V p-p of BAND, PTO and PRESELECTOR signal. I'll be interested to hear of your progress. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com Griffiths G. wrote: Garey - Many thanks. Linking across the (disconnected) filter brings the bandwidth to what one would expect with just the IFTs at first IF. The selectivity is then properly controlled at the bandpass LC filter as it should be. I removed T6, the xtal filter can. There are only two xtals in a simple half lattice configuration (marked 5645 and 5642kHz), no internal capacitors, and the matching transformer at the output is not quite as in the circuit in the manual I have. There it is shown as an autotransformer, in reality it has two windings, the common output of the two xtals being to the hot end of the low impedance primary winding at the earthy end of the secondary. Hence, electrically, virtually no different to the circuit. Out of the receiver, the filter tests OK with a sig gen, the two xtals working, no sign of a problem, with series resonance at 5644.7 and 5641.0kHz. So the next test when I have a workshop session will be on T5 secondary, perhaps the secondary connected to the 5642kHz xtal has a problem. By the way, the receiver is about 40dB low on sensitivity as well (I bought it that way earlier this year - in need of a challenge!). So far, I have the RF amplifier documented, but ideally would be good to compare to a fully working set. T1 has a measured Q of 60 at 3.6MHz, and a step up of about 2.5. gm of the 6BZ6 at the bias point is about 2mA/V, and with the calculated dynamic impedance of T2 at 3.6MHz of 4500 ohms, the stage gain is theoretically 9, though I measure 7, so not far off. I intend to go through like this, stage by stage, as I've yet to find whether this level of detail is already available. 73 Gwyn G3ZIL From: drakelist-boun...@zerobeat.net [drakelist-boun...@zerobeat.net] On Behalf Of Garey Barrell [k4...@mindspring.com] Sent: 18 July 2010 14:46 To: drakelist Subject: Re: [Drakelist] R4B xtal filter bandwidth problem Gwyn - Certainly sounds like a bad filter. Can't say I've ever seen or heard of one failing that way. Seems highly unlikely. I'd start by just connecting a wire between the leads going to the input and output of the filter, after disconnecting them from the filter itself. The filter is most likely just a series of four (it's a four pole filter) crystals connected in series with small caps to ground between them. It's a little hard to imagine THREE crystals all failing or coming 'unglued' at the same time. I assume this was a catastrophic failure. Does the receiver still seem about the same sensitivity, just restricted? Let us know what you find! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com Griffiths G. wrote: Folks Does anyone have experience of the R4B as-fitted xtal fliter showing a -3dB bandwidth of just 250Hz, from 5644.910 to 5644.660kHz This suggests to me that only one crystal is in circuit, but I do not have the circuit of what is in the can so I can be sure. Is there a circuit available? Before I dismantle, suggestions welcome as to any other diagnostics I can do. many thanks 73s, Gwyn Griffiths G3ZIL ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] R4B xtal filter bandwidth problem
Gwyn - Sorry, read 'Plate-Suppressor' short below. Very interesting. I've been fortunate to avoid this sort of problem in almost 50 years of working on Drake gear! :-) I would suspect T5 at this point as well because it's about the only other thing around! I assume you have subbed a 12BE6, a 'shaky' tube at best. I HAVE seen transformers like T5 'partially' fail due to a Screen-Suppressor short in V2, sometimes burning R9 in the process. The excess current damages the insulation on the winding, causing shorted turn(s). The 'repairman' replaces the tube, and fried resistor, and when that doesn't fix it, sells it as 'working perfectly' :-) It's possible your low sensitivity is related to damage in T5 as well. The only information I have that might be useful is to expect ~1.5 to 2V p-p of BAND, PTO and PRESELECTOR signal. I'll be interested to hear of your progress. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com Griffiths G. wrote: Garey - Many thanks. Linking across the (disconnected) filter brings the bandwidth to what one would expect with just the IFTs at first IF. The selectivity is then properly controlled at the bandpass LC filter as it should be. I removed T6, the xtal filter can. There are only two xtals in a simple half lattice configuration (marked 5645 and 5642kHz), no internal capacitors, and the matching transformer at the output is not quite as in the circuit in the manual I have. There it is shown as an autotransformer, in reality it has two windings, the common output of the two xtals being to the hot end of the low impedance primary winding at the earthy end of the secondary. Hence, electrically, virtually no different to the circuit. Out of the receiver, the filter tests OK with a sig gen, the two xtals working, no sign of a problem, with series resonance at 5644.7 and 5641.0kHz. So the next test when I have a workshop session will be on T5 secondary, perhaps the secondary connected to the 5642kHz xtal has a problem. By the way, the receiver is about 40dB low on sensitivity as well (I bought it that way earlier this year - in need of a challenge!). So far, I have the RF amplifier documented, but ideally would be good to compare to a fully working set. T1 has a measured Q of 60 at 3.6MHz, and a step up of about 2.5. gm of the 6BZ6 at the bias point is about 2mA/V, and with the calculated dynamic impedance of T2 at 3.6MHz of 4500 ohms, the stage gain is theoretically 9, though I measure 7, so not far off. I intend to go through like this, stage by stage, as I've yet to find whether this level of detail is already available. 73 Gwyn G3ZIL From: drakelist-boun...@zerobeat.net [drakelist-boun...@zerobeat.net] On Behalf Of Garey Barrell [k4...@mindspring.com] Sent: 18 July 2010 14:46 To: drakelist Subject: Re: [Drakelist] R4B xtal filter bandwidth problem Gwyn - Certainly sounds like a bad filter. Can't say I've ever seen or heard of one failing that way. Seems highly unlikely. I'd start by just connecting a wire between the leads going to the input and output of the filter, after disconnecting them from the filter itself. The filter is most likely just a series of four (it's a four pole filter) crystals connected in series with small caps to ground between them. It's a little hard to imagine THREE crystals all failing or coming 'unglued' at the same time. I assume this was a catastrophic failure. Does the receiver still seem about the same sensitivity, just restricted? Let us know what you find! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com Griffiths G. wrote: Folks Does anyone have experience of the R4B as-fitted xtal fliter showing a -3dB bandwidth of just 250Hz, from 5644.910 to 5644.660kHz This suggests to me that only one crystal is in circuit, but I do not have the circuit of what is in the can so I can be sure. Is there a circuit available? Before I dismantle, suggestions welcome as to any other diagnostics I can do. many thanks 73s, Gwyn Griffiths G3ZIL ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] WTB Drake TR4C +AC4
WTB Drake TR4C +AC4 paypal , shipping to NJ please offers to email Thanks Serge___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Wanted AC-4
I need a good working AC-4. I really do. KB8NXO ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
