Re: [Drakelist] What have I done now?
Hi Curt, Thanks for your advice. I have copied the list in now as you suggest. I do have Gary's excellent CD. Regrettably I did not catch it in time. Great pity it was all tested out okay all bands ready for an antenna! 73 Damien Date: Thu, 13 Mar 2014 13:24:28 -0500 From: cptc...@flash.net To: damienman...@hotmail.com; drakelist@zerobeat.net Subject: Re: [Drakelist] What have I done now? Hi Damien: Yes, especially when replying to posts, be sure to note where the reply is directed address-wise. Always good to copy the list as well as any direct message so others can follow along with the discussion responses. The scenario Garey outlined is very likely indeed. It kind of was an extension of my comment about it is sometimes hard to tell exactly what was going to happen in all stages of the rig. He went into the schematic a little deeper than I did--All of those guys are very knowledgeable in the Drake line-up. If you plan to do much work at all on these rigs, Garey's CD with annotated pictures and notes is the best available as far as I know. Hopefully, you caught it before the finals or other parts got damaged. BTW, a fan pulling air out of the back of the cage is a great benefit to these rigs to shed some of the heat. That being said, these things will run 24/7 at rated output in tough modes like RTTY and just keep going--they are very robust as long as properly loaded. Cheers Curt On 3/13/2014 11:20 AM, Damien Mannix wrote: Hi Curt, Thanks again. I will do everything you suggest. Actually I am puzzled myself as to how the list works nowadays! I did in fact also hear from Mike Bryce (no call sign given), Evan K9SQG and Gary K4OAH who also kindly invited me to join the DrakeRadio group. Never knew it existed but I will certainly join. Regards, Damien G3XER Date: Thu, 13 Mar 2014 11:07:11 -0500 From: cptc...@flash.net To: damienman...@hotmail.com; drakelist@zerobeat.net Subject: Re: [Drakelist] What have I done now? Hi Damien: Doesn't change my thoughts really. Even tho the relay for Tx would not be engaged, and this keeps the cathodes floating and not grounded, with bias very low or removed from the grids, the tubes will conduct enough to get hot for sure. I think the worst is that the current comes thru the grids so can physically damage the tube internals. Which tubes, finals or driver, or others, is a guess only--perhaps all to some degree. I would just power it up again with a full on AC4 and monitor it closely to be sure nothing has gotten burned or out of tolerance enough to do damage. Especially, confirm that the bias control does what it is supposed to do with adjustment range, verify that the current reading of plate current is close (be careful!) and do an operational check-out. These are very robust rigs but the finals are especially intolerant of unloaded or excessive plate current being that they are TV sweep tubes. Let us know how it goes. Kind of surprised we haven't heard from anyone else on the list. Curt KU8L On 3/13/2014 10:31 AM, Damien Mannix wrote: Hi Curt, Thank you for your two replies. I am most grateful for your input. How one can be misled. I certainly thought I was doing the right thing! No sure if it makes any difference to your conclusions but I never switched to transmit I just left the TR4 in Receive mode. 73 Damien Date: Thu, 13 Mar 2014 08:25:26 -0500 From: cptc...@flash.net To: drakelist@zerobeat.net Subject: Re: [Drakelist] What have I done now? Thinking about it a little more, since it may or may not have transitioned to TX, the driver or any of the other tubes that are bias controlled can do the same at reduced voltages
Re: [Drakelist] What have I done now?
Hi Garey, Thank you for going to so much trouble. I am embarrassed by your kindness. I have followed your advice as far as possible and appreciate the reminder about lethal voltages. Having inspected the P.A. compartment, above and below the chassis, in minute detail I cannot see any sign of overheating or stress. The 3 x 15 ohm resisters look like brand new and check out okay. The P.A. tubes have opaque silver circles, about the size of a Quarter, on opposite sides of the glass envelope. Probably that is normal! Unfortunately that is as far as I can go as the radio is pretty well dead. So irritating when on Monday of this week it checked out fine on all bands and was just waiting for a proper antenna instead of a dummy load. I really have screwed things up! To be more specific, when powered it lights up the tubes, the ones I can tell in daylight anyway, including the heaters in the one P.A. tube I have left in place. However the S meter does not move at all and there is no hiss in the speaker. The Plate meter does not move at all no matter what I do with any tuning control. As you so rightly put it ' there are probably other failed components that will have to be identified and replaced'. Unless something really simple comes to your mind I doubt that I am the right person to pursue this. Whilst I am anxious to learn about and maintain this equipment eventually, I doubt that with my present so limited knowledge I will be able to cope with the problem. What I am going to do is ask the net if any British Drake fans know who is the best person over here with Drake service experience. Again many thanks for your help. 73 Damien G3XER Date: Thu, 13 Mar 2014 12:27:53 -0400 From: k4...@mindspring.com To: damienman...@hotmail.com Subject: Re: [Drakelist] What have I done now? Damien - We're glad to have you join us.! It's a good group, and they all love Drake gear :-) Unfortunately, no. The problem is almost certainly that at one point the Plate and Screen voltages on the PA were 'up' and the BIAS voltage was not high enough to keep the T-R relay cut off. The causes the radio to go into TRANSMIT mode and probably being un-tuned, the PA had to dissipate well in excess of it's rated power. Depending upon how things worked out, you most likely have damaged one or more of the PA tubes. If so, it will be impossible to evaluate the transmitter condition accurately until they have been replaced. ***CAREFUL! THERE ARE LETHAL VOLTAGES BOTH ABOVE AND BELOW CHASSIS. WAIT AT LEAST 5 MINUTES AFTER SWITCHING OFF BEFORE TOUCHING ANYTHING INSIDE THE RADIO. *** What I would suggest is to disconnect the power supply from the radio, and carefully examine the chassis area under the PA. Check the 15 ohm resistors across each of the three sockets for value and condition, and look for any evidence of overheating. Then remove two of the PA tubes, placing the plate caps well clear of the shielding. Reconnect the power supply, let the radio warm up for 10 minutes in Receive. Set the XMTR GAIN control to minimum and switch to 'X-CW'. The PLATE meter should read about 30 mA. If it does NOT, adjust the BIAS pot on the power supply to set it to 30 mA. Then switch to SSB, power off, wait five minutes, and then remove the single PA tube and put another one in the SAME socket. Power on and NOTE the PLATE current reading. Hopefully it will be very close to 30 mA. If not, write down the reading and power down. Repeat for the third tube as above. If all three are reasonably close to 30 mA, you can proceed. IF one or more are considerably different (30 +/- 10%) you will need new PA tubes. If NO PLATE current is displayed, there are probably other failed components that will have to be identified and replaced. Report back with your progress!! 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 Damien Mannix wrote: Gary, Thanks, I will be delighted to join your group. Did not know it existed! Sorry. Obviously I have received bad advice about bringing old equipment to life. Something to do with reforming electrolytics I believe! The TR4 was never switched to transmit just left in Receive mode. May I trouble you again by asking if you think that makes an difference to your views? 73, Damien G3XER Date: Wed, 12 Mar 2014 13:45:57 -0400 From: k4...@mindspring.com To: damienman...@hotmail.com Subject: [Drakelist] What have I done now? Damien - Sorry for the rant! I got so wrapped up in your problem that I forgot to ask you to join us. It just hurts that so much gear is damaged by 'internet engineers' and the 'rules' that they promulgate. I sent you an invitation to the DrakeRadio group. It is a much more active
Re: [Drakelist] What have I done now?
Thinking about it a little more, since it may or may not have transitioned to TX, the driver or any of the other tubes that are bias controlled can do the same at reduced voltages. Hope there was no long term damage. I once worked on a FT101E that had a defective socket on the grid of one of the finals. As soon as HV came on, with that grid floating, it began cooking. Bias measured OK, all voltages lookedOK, but no bias was getting to the actual tube--duh! I finally figured out what was going on after the tube got so hot, the vacuum sucked a hole thru the side of the tube. Still have that tube BTW...reminder.. Curt KU8L On 3/12/2014 12:18 PM, Damien Mannix wrote: Hi all, Still waiting for better weather to put up an antenna but then ready to go with my TR4/AC4 which are fine into a dummy load, or at least they were! Bought a, supposedly good, AC4 as a spare. Decided to power it up gradually with the TR4 as a load. Two hours at 50v, two at 80v, two at 110v, two at 140v. No problems and a fan on the rear behind the PA begins to run at this voltage. Then, ten minutes at 170v and 'wow' what is that smell? I thought it was my shack heater. No it was the TR4. The top, above the forward most PA tube, was unbelievably hot. Switched off immediately of course. Can't spot anything untoward in the PA compartment so after a complete cool down I took it slowly up to 230v with my usual AC4. Not done a full test but it seems perfectly happy again, heat and smell wise, after 30 minutes at 230v. Might I have ruined anything and, presumably, the fault is in the AC4. Thanks in advance for any thoughts. 73 Damien G3XER ___ 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] What have I done now?
Hi Damien: Doesn't change my thoughts really. Even tho the relay for Tx would not be engaged, and this keeps the cathodes floating and not grounded, with bias very low or removed from the grids, the tubes will conduct enough to get hot for sure. I think the worst is that the current comes thru the grids so can physically damage the tube internals. Which tubes, finals or driver, or others, is a guess only--perhaps all to some degree. I would just power it up again with a full on AC4 and monitor it closely to be sure nothing has gotten burned or out of tolerance enough to do damage. Especially, confirm that the bias control does what it is supposed to do with adjustment range, verify that the current reading of plate current is close (be careful!) and do an operational check-out. These are very robust rigs but the finals are especially intolerant of unloaded or excessive plate current being that they are TV sweep tubes. Let us know how it goes. Kind of surprised we haven't heard from anyone else on the list. Curt KU8L On 3/13/2014 10:31 AM, Damien Mannix wrote: Hi Curt, Thank you for your two replies. I am most grateful for your input. How one can be misled. I certainly thought I was doing the right thing! No sure if it makes any difference to your conclusions but I never switched to transmit I just left the TR4 in Receive mode. 73 Damien Date: Thu, 13 Mar 2014 08:25:26 -0500 From: cptc...@flash.net To: drakelist@zerobeat.net Subject: Re: [Drakelist] What have I done now? Thinking about it a little more, since it may or may not have transitioned to TX, the driver or any of the other tubes that are bias controlled can do the same at reduced voltages. Hope there was no long term damage. I once worked on a FT101E that had a defective socket on the grid of one of the finals. As soon as HV came on, with that grid floating, it began cooking. Bias measured OK, all voltages lookedOK, but no bias was getting to the actual tube--duh! I finally figured out what was going on after the tube got so hot, the vacuum sucked a hole thru the side of the tube. Still have that tube BTW...reminder.. Curt KU8L On 3/12/2014 12:18 PM, Damien Mannix wrote: Hi all, Still waiting for better weather to put up an antenna but then ready to go with my TR4/AC4 which are fine into a dummy load, or at least they were! Bought a, supposedly good, AC4 as a spare. Decided to power it up gradually with the TR4 as a load. Two hours at 50v, two at 80v, two at 110v, two at 140v. No problems and a fan on the rear behind the PA begins to run at this voltage. Then, ten minutes at 170v and 'wow' what is that smell? I thought it was my shack heater. No it was the TR4. The top, above the forward most PA tube, was unbelievably hot. Switched off immediately of course. Can't spot anything untoward in the PA compartment so after a complete cool down I took it slowly up to 230v with my usual AC4. Not done a full test but it seems perfectly happy again, heat and smell wise, after 30 minutes at 230v. Might I have ruined anything and, presumably, the fault is in the AC4. Thanks in advance for any thoughts. 73 Damien G3XER ___ Drakelist mailing list Drakelist@zerobeat.net mailto: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] What have I done now?
Hi Damien: Yes, especially when replying to posts, be sure to note where the reply is directed address-wise. Always good to copy the list as well as any direct message so others can follow along with the discussion responses. The scenario Garey outlined is very likely indeed. It kind of was an extension of my comment about it is sometimes hard to tell exactly what was going to happen in all stages of the rig. He went into the schematic a little deeper than I did--All of those guys are very knowledgeable in the Drake line-up. If you plan to do much work at all on these rigs, Garey's CD with annotated pictures and notes is the best available as far as I know. Hopefully, you caught it before the finals or other parts got damaged. BTW, a fan pulling air out of the back of the cage is a great benefit to these rigs to shed some of the heat. That being said, these things will run 24/7 at rated output in tough modes like RTTY and just keep going--they are very robust as long as properly loaded. Cheers Curt On 3/13/2014 11:20 AM, Damien Mannix wrote: Hi Curt, Thanks again. I will do everything you suggest. Actually I am puzzled myself as to how the list works nowadays! I did in fact also hear from Mike Bryce (no call sign given), Evan K9SQG and Gary K4OAH who also kindly invited me to join the DrakeRadio group. Never knew it existed but I will certainly join. Regards, Damien G3XER Date: Thu, 13 Mar 2014 11:07:11 -0500 From: cptc...@flash.net To: damienman...@hotmail.com; drakelist@zerobeat.net Subject: Re: [Drakelist] What have I done now? Hi Damien: Doesn't change my thoughts really. Even tho the relay for Tx would not be engaged, and this keeps the cathodes floating and not grounded, with bias very low or removed from the grids, the tubes will conduct enough to get hot for sure. I think the worst is that the current comes thru the grids so can physically damage the tube internals. Which tubes, finals or driver, or others, is a guess only--perhaps all to some degree. I would just power it up again with a full on AC4 and monitor it closely to be sure nothing has gotten burned or out of tolerance enough to do damage. Especially, confirm that the bias control does what it is supposed to do with adjustment range, verify that the current reading of plate current is close (be careful!) and do an operational check-out. These are very robust rigs but the finals are especially intolerant of unloaded or excessive plate current being that they are TV sweep tubes. Let us know how it goes. Kind of surprised we haven't heard from anyone else on the list. Curt KU8L On 3/13/2014 10:31 AM, Damien Mannix wrote: Hi Curt, Thank you for your two replies. I am most grateful for your input. How one can be misled. I certainly thought I was doing the right thing! No sure if it makes any difference to your conclusions but I never switched to transmit I just left the TR4 in Receive mode. 73 Damien Date: Thu, 13 Mar 2014 08:25:26 -0500 From: cptc...@flash.net mailto:cptc...@flash.net To: drakelist@zerobeat.net mailto:drakelist@zerobeat.net Subject: Re: [Drakelist] What have I done now? Thinking about it a little more, since it may or may not have transitioned to TX, the driver or any of the other tubes that are bias controlled can do the same at reduced voltages. Hope there was no long term damage. I once worked on a FT101E that had a defective socket on the grid of one of the finals. As soon as HV came on, with that grid floating, it began cooking. Bias measured OK, all voltages lookedOK, but no bias was getting to the actual tube--duh! I finally figured out what was going on after the tube got so hot, the vacuum sucked a hole thru the side of the tube. Still have that tube BTW...reminder.. Curt KU8L On 3/12/2014 12:18 PM, Damien Mannix wrote: Hi all, Still waiting for better weather to put up an antenna but then ready to go with my TR4/AC4 which are fine into a dummy load, or at least they were! Bought a, supposedly good, AC4 as a spare. Decided to power it up gradually with the TR4 as a load. Two hours at 50v, two at 80v, two at 110v, two at 140v. No problems and a fan on the rear behind the PA begins to run at this voltage. Then, ten minutes at 170v and 'wow' what is that smell? I thought it was my shack heater. No it was the TR4. The top, above the forward most PA tube, was unbelievably hot. Switched off immediately of course. Can't spot anything untoward in the PA compartment so after a complete cool down I took it slowly up to 230v with my usual AC4. Not done a full
Re: [Drakelist] What have I done now?
I may get disagreement on this but I would NEVER bring up a PS like this attached to a transmitter. When you do that, the bias is minimal, and ven at low plate voltage, the finals are going to be conducting I suspect. Really hard to tell what is going to be happening. If you want to bring the supply itself up slowly, thats fine...THEN attached the rig and power it up normally. Curt KU8L A line, B line, TR4 TR3, TR7 On 3/12/2014 12:18 PM, Damien Mannix wrote: Hi all, Still waiting for better weather to put up an antenna but then ready to go with my TR4/AC4 which are fine into a dummy load, or at least they were! Bought a, supposedly good, AC4 as a spare. Decided to power it up gradually with the TR4 as a load. Two hours at 50v, two at 80v, two at 110v, two at 140v. No problems and a fan on the rear behind the PA begins to run at this voltage. Then, ten minutes at 170v and 'wow' what is that smell? I thought it was my shack heater. No it was the TR4. The top, above the forward most PA tube, was unbelievably hot. Switched off immediately of course. Can't spot anything untoward in the PA compartment so after a complete cool down I took it slowly up to 230v with my usual AC4. Not done a full test but it seems perfectly happy again, heat and smell wise, after 30 minutes at 230v. Might I have ruined anything and, presumably, the fault is in the AC4. Thanks in advance for any thoughts. 73 Damien G3XER ___ 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
