[Drakelist] WTB: L4B L7 power supply boards or rails

Fellow enthusiasts, Perhaps you've done the upgrade for the power supply used on the L4B and L7 linear amplifiers by installing the Harbach Electronics or Heathkit Shop boards. If so, you might be wondering what to do with the old, unused boards and/or rails. I have a need for some of

Re: [Drakelist] R-4A PTO, Round 1

Steve - Yes, it's quite possible that the internal Zener is 'sorta' conducting. They often fail in this way. The internal Zener is 10V. Cold spray is often helpful in isolating the troublemaker. How MUCH is the frequency shifting? Other parts that can cause these kinds of problems are the

Re: [Drakelist] R-4A PTO, Round 1

Paul brings up a good point. Does the frequency jump when tuning, or even when stopped? 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 Paul Christensen wrote: Steve, No doubt others with more experience will jump in.

Re: [Drakelist] R-4A PTO, Round 1

Hi Joe, NOW I understand---thanks for the clarification. I *think* those style of capacitors are called tubular temperature-compensating types---but the design is so very old I don't think they're even manufactured anymore...? My first fix with my PTO was traced to a bad solder connection

Re: [Drakelist] Drakelist Digest, Bias current Low

Fred - The first thing that comes to mind is that ONE of the PA tubes is DEAD. You can check by measuring the voltage across R32 or R33 in TUNE. Other possibilities are an open Screen or Cathode resistor (R30, 31, 32 or 33) Another possibility is that the HV power supply (AC-4), isn't.

Re: [Drakelist] TR-7 Off Frequency (1Khz)

Hi Brian, On Tue, 05 Jul 2011 13:26:33 -0400, bjon...@mindspring.com wrote: Finally I remembered my freq counter (keeps track of my 10Mhz frequency standard) so I hooked the drake up to it directly and threw a 1W cw tone at it and was off by 1Khz (i.e the DR7 displayed 14.2140, but the counter

[Drakelist] R-4C Cabinet Bumpers

With all the R-4C work going on here, I have managed to loose (or break and then loose) the two small top cabinet bumpers located at the top rear of the R-4C. These are black in color, flat, and are press-fit into the back top lip of the chassis. Anyone have a pair to sell or is the OEM still

Re: [Drakelist] R-4A PTO, Round 1

The frequency jumps when stopped and gets worse when it's fully warmed up. Re the dog-bone caps: can these be replaced by silver mica units? Or do they have a temperature coefficient that's different? I would still love to get a working PTO to swap in so I can not fear wrecking this one.

Re: [Drakelist] R-4A PTO, Round 1

- Original Message - From: Steve Wedge w1es1...@earthlink.net To: Drake List drakelist@zerobeat.net Sent: Tuesday, July 05, 2011 5:52 PM Subject: Re: [Drakelist] R-4A PTO, Round 1 The frequency jumps when stopped and gets worse when it's fully warmed up. Re the dog-bone caps: can

Re: [Drakelist] R-4A PTO, Round 1

Steve - OK. Well that's more likely to be a Zener or cap problem. Perhaps bad solder. The brown mica caps are just NP0 mica's. They are still being made and available. The TC caps, (the white, tubular ones,) are no longer made, and unfortunately the color codes are not consistent. Some

Re: [Drakelist] R-4A PTO, Round 1

On Tue, 5 Jul 2011 18:37:35 -0700, Richard Knoppow wrote: While Freeze Mist or its clones, have gotten expensive they are still available. You don't need much. Canned air can be used as freeze mist, just hold the can upside down. 73 -Jim -- Ham Radio NU0C Lincoln, Nebraska, U.S.S.A.

Re: [Drakelist] R-4A PTO, Round 1

Shh, Jim, don't tell the Feds or they will outlaw it :-) 73, Don ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist