[Drakelist] Me too...
Add in SBCGLOBAL (ATT) and/or Yahoo Mail! Bob K9JU ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] R4B Audio Distortion
Update: resolved, and another gold star for Garey In early February, I asked for ideas after finding my R4B audio output stage running hot. Positive bias, climbing slowly to +3, would mysteriously appear on the grid after a few minutes of operation, and the audio became distorted. Cooling the tube with forced air mitigated the problem, reducing but not eliminating the weird grid bias. I could find no defective components (leaking caps, thermally-misbehaving cathode resistor, etc.) and had tried three different tubes that behaved the same way. Richard WB6KBL suggested I look for some way that screen voltage might be leaking to the adjacent grid pin on the socket. I could find nothing by inspection, and cleaning made no difference. I began a half-hearted search through my junk box for a replacement socket, but didn't end up going that way. Garey K4OAH thought the symptoms clearly suggested a gassy tube. I was skeptical, having tried several different tubes, both 6EH5 and 6CA5, all of which tested OK (and not gassy) on a borrowed Hickok 600A tester. Garey pointed out that 6CA5 is not an exact replacement and that in his experience it has sometimes been necessary to go through several 6EH5s to find a good one. So I decided it was cheap enough, at $3 each from most sources, to obtain a couple more tubes and see what happened. I've finally done that, and, lo, it appears Garey was correct. One (and only one) of my new tubes behaves properly. Of course (sigh) the R4B has now gone of the rails for some entirely new reason, but I'll open it up soon and see what's what. 73, and thanks for the help. Randy WB4SPB ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] R4B Audio Distortion
Out of curiosity, how many 6EH5 tubes did you have to go through to find a good one? Al, n7ioh Payson, Arizona, USA On Fri, Mar 9, 2012 at 11:24 AM, Randy WB4SPB wb4...@earthlink.net wrote: Update: resolved, and another gold star for Garey In early February, I asked for ideas after finding my R4B audio output stage running hot. Positive bias, climbing slowly to +3, would mysteriously appear on the grid after a few minutes of operation, and the audio became distorted. Cooling the tube with forced air mitigated the problem, reducing but not eliminating the weird grid bias. I could find no defective components (leaking caps, thermally-misbehaving cathode resistor, etc.) and had tried three different tubes that behaved the same way. Richard WB6KBL suggested I look for some way that screen voltage might be leaking to the adjacent grid pin on the socket. I could find nothing by inspection, and cleaning made no difference. I began a half-hearted search through my junk box for a replacement socket, but didn't end up going that way. Garey K4OAH thought the symptoms clearly suggested a gassy tube. I was skeptical, having tried several different tubes, both 6EH5 and 6CA5, all of which tested OK (and not gassy) on a borrowed Hickok 600A tester. Garey pointed out that 6CA5 is not an exact replacement and that in his experience it has sometimes been necessary to go through several 6EH5s to find a good one. So I decided it was cheap enough, at $3 each from most sources, to obtain a couple more tubes and see what happened. I've finally done that, and, lo, it appears Garey was correct. One (and only one) of my new tubes behaves properly. Of course (sigh) the R4B has now gone of the rails for some entirely new reason, but I'll open it up soon and see what's what. 73, and thanks for the help. Randy WB4SPB __**_ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/**mailman/listinfo/drakelisthttp://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] R4B Audio Distortion
Randy, Great news! Glad it is resolved...I'll keep that one in mind for future bugs. One more GOLD star for Garey is right! He is super and If he actually had a gold start for all of the things he has helped us with...it would take a very large wall indeed to display them! 73, Lee -Original Message- From: Randy WB4SPB wb4...@earthlink.net To: drakelist drakelist@zerobeat.net Sent: Fri, Mar 9, 2012 1:33 pm Subject: Re: [Drakelist] R4B Audio Distortion Update: resolved, and another gold star for Garey In early February, I asked for ideas after finding my R4B audio output stage running hot. Positive bias, climbing slowly to +3, would mysteriously appear on the grid after a few minutes of operation, and the audio became distorted. Cooling the tube with forced air mitigated the problem, reducing but not eliminating the weird grid bias. I could find no defective components (leaking caps, thermally-misbehaving cathode resistor, etc.) and had tried three different tubes that behaved the same way. Richard WB6KBL suggested I look for some way that screen voltage might be leaking to the adjacent grid pin on the socket. I could find nothing by inspection, and cleaning made no difference. I began a half-hearted search through my junk box for a replacement socket, but didn't end up going that way. Garey K4OAH thought the symptoms clearly suggested a gassy tube. I was skeptical, having tried several different tubes, both 6EH5 and 6CA5, all of which tested OK (and not gassy) on a borrowed Hickok 600A tester. Garey pointed out that 6CA5 is not an exact replacement and that in his experience it has sometimes been necessary to go through several 6EH5s to find a good one. So I decided it was cheap enough, at $3 each from most sources, to obtain a couple more tubes and see what happened. I've finally done that, and, lo, it appears Garey was correct. One (and only one) of my new tubes behaves properly. Of course (sigh) the R4B has now gone of the rails for some entirely new reason, but I'll open it up soon and see what's what. 73, and thanks for the help. Randy WB4SPB ___ 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 Audio Distortion
Altogether, I bought two 6EH5s and one 6CA5. I already had a spare 6EH5, so, considering those alone, I had to try three to get one. If I count the 6CA5 that I bought, I had to try four to get one. The 6CA5 IS very similar. Some sources do not even have the 6EH5 and refer you to 6CA5. The tube that originally manifested the problem was a 6CA5 that had been in the radio for many years before these symptoms appeared. Whether the difference in 6EH5 and 6CA5 is important here, I cannot say. I'll stick with 6EH5s in the future, while I can get them. For sources I've seen that have both, the price is the same. 73, Randy WB4SPB - Original Message - From: Al Al Out of curiosity, how many 6EH5 tubes did you have to go through to find a good one? Al, n7ioh Payson, Arizona, USA ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] DUH
One of the reasons the list is archived is to allow subscribers a way to see if the list is generating mail, even if they are not receiving messages, You can access the archives at http://www.mail-archive.com/drakelist@zerobeat.net/ I have received a lot of messages from folks who use Comcast and other ISPs that have recently reject mail, both from the list and myself. Apparently old dns information about the server was stored in their cache, and their automatic spam traps rejected the mail. The mailing list software on myserver disables mail to accounts that have excessive bounces...so if your ISP blocks message from here, sooner or later your account gets disabled. I manually reviewed all accounts and reactivated accounts that had been disabled. So, you ask, how come Thom did not answer my email? Well, if thom answered it, and your ISP was blocking mail from my server...then you never got the answer. So, if the mail stops for you...look in the archive and see if the list is still alive. If it is, your ISP may be blocking the mail. You might want to experience further frustration by contacting your ISP. Sorry for the inconvenience. Thom k3hrn ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] R4B Audio Distortion
I wonder. when drake assembled the radios, did they go through three or fours tubes per radio to get one that worked correctly? dosen't seem logical. And although you can't argue with the fact that the subing out the tube fixed the problem, I wonder if there is something hidden down someplace in the design that causes the problem just a thought Mike, wb8vge On Mar 9, 2012, at 4:25 PM, Randy WB4SPB wrote: Altogether, I bought two 6EH5s and one 6CA5. I already had a spare 6EH5, so, considering those alone, I had to try three to get one. If I count the 6CA5 that I bought, I had to try four to get one. The 6CA5 IS very similar. Some sources do not even have the 6EH5 and refer you to 6CA5. The tube that originally manifested the problem was a 6CA5 that had been in the radio for many years before these symptoms appeared. Whether the difference in 6EH5 and 6CA5 is important here, I cannot say. I'll stick with 6EH5s in the future, while I can get them. For sources I've seen that have both, the price is the same. 73, Randy WB4SPB - Original Message - From: Al Al Out of curiosity, how many 6EH5 tubes did you have to go through to find a good one? Al, n7ioh Payson, Arizona, USA ___ 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 Audio Distortion
Mike - I think the problem is that 'new' tubes are 50 years old.. Even a few molecules of air a day adds up after that long. When Drake assembled the radios, the tubes were _really_ new!! The 6EH5 gets 'really' hot in normal operation, and perhaps the heat/cool cycles are harder on the metal/glass seals at the pins. Some tubes definitely are more prone to 'gas' (grid emission), the 12BA6 comes to mind. That one shows as a 'drifting' S-Meter as the tubes heat up. The 6EJ7 is prone to noise in 3rd Mixer service, probably for a similar reason. The only answer I have come up with is to keep trying tubes until you get a 'good' one. 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 Mike Bryce wrote: I wonder. when drake assembled the radios, did they go through three or fours tubes per radio to get one that worked correctly? dosen't seem logical. And although you can't argue with the fact that the subing out the tube fixed the problem, I wonder if there is something hidden down someplace in the design that causes the problem just a thought Mike, wb8vge On Mar 9, 2012, at 4:25 PM, Randy WB4SPB wrote: Altogether, I bought two 6EH5s and one 6CA5. I already had a spare 6EH5, so, considering those alone, I had to try three to get one. If I count the 6CA5 that I bought, I had to try four to get one. The 6CA5 IS very similar. Some sources do not even have the 6EH5 and refer you to 6CA5. The tube that originally manifested the problem was a 6CA5 that had been in the radio for many years before these symptoms appeared. Whether the difference in 6EH5 and 6CA5 is important here, I cannot say. I'll stick with 6EH5s in the future, while I can get them. For sources I've seen that have both, the price is the same. 73, Randy WB4SPB - Original Message - *From:*Al Al mailto:wenj...@gmail.com Out of curiosity, how many 6EH5 tubes did you have to go through to find a good one? Al, n7ioh Payson, Arizona, USA _ ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] R4B Audio Distortion
I just wound up fixing an R-4C - and one of the things I did was to swap V4 and V6. That single exchange did more to reduce the noise in the receiver than anyting else I could have done. I did go on and convert the third mixer to cathode-feed, and that improved things a bit more, but you're on to something with respect to the audio output. OTOH, I still sit here and wonder. At audio frequencies, is everything as designed by Drake really that critical? It might be a good time to replace components to find out... Yeah - I'm a troublemaker... Steve Wedge, W1ES/4 I can't complain, but sometimes I still do. - Joe Walsh If the above message appears, it came from Steve's Son of Laptop! - Original Message - From: Garey Barrell k4...@mindspring.com To: Mike Bryce proso...@sssnet.com Cc: Randy WB4SPB wb4...@earthlink.net; drakelist@zerobeat.net Sent: Friday, March 09, 2012 10:21 PM Subject: Re: [Drakelist] R4B Audio Distortion Mike - I think the problem is that 'new' tubes are 50 years old.. Even a few molecules of air a day adds up after that long. When Drake assembled the radios, the tubes were _really_ new!! The 6EH5 gets 'really' hot in normal operation, and perhaps the heat/cool cycles are harder on the metal/glass seals at the pins. Some tubes definitely are more prone to 'gas' (grid emission), the 12BA6 comes to mind. That one shows as a 'drifting' S-Meter as the tubes heat up. The 6EJ7 is prone to noise in 3rd Mixer service, probably for a similar reason. The only answer I have come up with is to keep trying tubes until you get a 'good' one. 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 Mike Bryce wrote: I wonder. when drake assembled the radios, did they go through three or fours tubes per radio to get one that worked correctly? dosen't seem logical. And although you can't argue with the fact that the subing out the tube fixed the problem, I wonder if there is something hidden down someplace in the design that causes the problem just a thought Mike, wb8vge On Mar 9, 2012, at 4:25 PM, Randy WB4SPB wrote: Altogether, I bought two 6EH5s and one 6CA5. I already had a spare 6EH5, so, considering those alone, I had to try three to get one. If I count the 6CA5 that I bought, I had to try four to get one. The 6CA5 IS very similar. Some sources do not even have the 6EH5 and refer you to 6CA5. The tube that originally manifested the problem was a 6CA5 that had been in the radio for many years before these symptoms appeared. Whether the difference in 6EH5 and 6CA5 is important here, I cannot say. I'll stick with 6EH5s in the future, while I can get them. For sources I've seen that have both, the price is the same. 73, Randy WB4SPB - Original Message - *From:*Al Al mailto:wenj...@gmail.com Out of curiosity, how many 6EH5 tubes did you have to go through to find a good one? Al, n7ioh Payson, Arizona, USA _ ___ 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
