Re: [Drakelist] TR7 problem
On Wed, 10 Aug 2011 21:03:32 -0700, dpetersen tds.net wrote: > the frequency (for 20 meters) goes to around 11.5 MHz and starts tuning > upwards rapidly, finally slowing to a stop after about a minute. 10 meters > starts at about 26 MHz and scrolls the same way. I can hear signals go by as > it scrolls. All other bands seem OK. > >Any ideas from the think tank? Oxidized Molex pin connectors on the PC boards. Lots of talk on this subject in the list archive. 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://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR7 problem
Hello Group: I am the recent recipient of a Drake TR7 with the PS7 power supply. It has evidently been in its original carton since 1987 and is in pristine condition. I fired it up to check it out and all seems well except on 20 and 10 meters. When switched to those bands the frequency (for 20 meters) goes to around 11.5 MHz and starts tuning upwards rapidly, finally slowing to a stop after about a minute. 10 meters starts at about 26 MHz and scrolls the same way. I can hear signals go by as it scrolls. All other bands seem OK. Any ideas from the think tank? -- 73, Dan - W7OIL *=== = = = = === === === === = = = === === === = = = === = = ** * ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Okay, so what IS the big brown thing?
Steve - No, that is a glass cap. Painted white with marks of color coding. The numbers refer to the capacitance AND the temperature characteristic. These hardly EVER go bad. The large, brown cap is the Dur Mica silver mica cap and is the one that we are trying to eliminate as the problem. Try to not disturb the arrangement of the leads of these 'flying' caps as they are part of the t/c and affect the temperature compensation. Others are just small value trimming caps to fine tune the coil and affect the linearity of the PTO. 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 Steve Wedge wrote: I was assuming that the "dogbone" cap in the PTO was the one that goes to the front of the inductor, has two white "dumb-bell" caps connected to that lead and then connects at the other end to what is actually the 3000 pf SM. It appears to be some sort of ceramic and is marked (from the end) BRN-WHT-ORG-BLK-RED, which, if normal colour codes were used would be 1-9-3-0-2 or 2-0-3-9-1. It seems to correspond in placement to C143-144-145, except that the two dumb-bells aren't in parallel. Isn't this the capacitor that has gone funky on a few PTO's? ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Okay, so what IS the big brown thing?
I was assuming that the "dogbone" cap in the PTO was the one that goes to the front of the inductor, has two white "dumb-bell" caps connected to that lead and then connects at the other end to what is actually the 3000 pf SM. It appears to be some sort of ceramic and is marked (from the end) BRN-WHT-ORG-BLK-RED, which, if normal colour codes were used would be 1-9-3-0-2 or 2-0-3-9-1. It seems to correspond in placement to C143-144-145, except that the two dumb-bells aren't in parallel. Isn't this the capacitor that has gone funky on a few PTO's? 73, Steve Wedge, W1ES/4 To be is to do - Socrates To do is to be - Plato Do be do be do. - Sinatra All my computers have my signature with various pearls of wisdom appended thereto. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] L7 arc/short
sounds like a dirty plate choke at the rear of the amplifier deck, rgds Jeff/9Y4J From: "Johanson, Paul" To: "drakelist@zerobeat.net" Sent: Wednesday, August 10, 2011 2:34 PM Subject: [Drakelist] L7 arc/short My L7 has developed a perplexing problem. Occasionally. when the power switch is energized a loud pop and sparks can be seen in the back of the amplifier. The HV remains fine, the power supply does not trip out, and the amplifier seems to be completely unaffected. I have opened the RF deck and there is no sign of any arcing. Has anyone else experienced anything like this? I don't want to keep turning it on and off to try and see the exact location of the arc as I'm sure it will eventually destroy something. It doesn't do it every time I turn it on; it malfunctions about once every ten tries. Any ideas? Many thanks! Paul N1OD ___ 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] Drake 2B Looong warmup
Try a shot of DeoxIT on the grounding wipers of the MAIN TUNING capacitor. If no luck, try subbing V3, V4 and/or V7. Report back! :-) 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 rhule...@comcast.net wrote: I own a Drake 2B which recently seems to take about an hour to achieve stable operation. By that, I mean listening to a cw signal, the tone will sound like a sick canary for about an hour after turning on the receiver. After that, operation is normal. This behavior happens regardless of band used. Anyone else ever experience similar behavior? ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] L7 arc/short
My L7 has developed a perplexing problem. Occasionally. when the power switch is energized a loud pop and sparks can be seen in the back of the amplifier. The HV remains fine, the power supply does not trip out, and the amplifier seems to be completely unaffected. I have opened the RF deck and there is no sign of any arcing. Has anyone else experienced anything like this? I don't want to keep turning it on and off to try and see the exact location of the arc as I'm sure it will eventually destroy something. It doesn't do it every time I turn it on; it malfunctions about once every ten tries. Any ideas? Many thanks! Paul N1OD ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Drake 2B Looong warmup
I own a Drake 2B which recently seems to take about an hour to achieve stable operation. By that, I mean listening to a cw signal, the tone will sound like a sick canary for about an hour after turning on the receiver. After that, operation is normal. This behavior happens regardless of band used. Anyone else ever experience similar behavior? ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
