- 1. [AMPS] PA-77 musings (score: 1)
- Author: N7CXI@SiliconPixels.com (Jim Barber)
- Date: Sun, 27 May 2001 17:11:24 -0700
- Hi folks, I recently bought a "basket case" PA-77. (single 8877) The OM decided to shoehorn a Dahl A77S transformer (1.2A CCS) and a 32uf filter into the case. He succeeded mechanically, but moved mo
- /archives//html/Amps/2001-05/msg00468.html (8,895 bytes)
- 2. [AMPS] PA-77 musings (score: 1)
- Author: 2@vc.net (2)
- Date: Sun, 27 May 2001 20:33:20 -0700
- ? Jim ? RF-switching shifts to non-linear bias during soft syllables. The amplifier's T/R bias should always be in sync with the T/R state in the transceiver. ? 8 - 10 % drop is more likely for a C-
- /archives//html/Amps/2001-05/msg00472.html (8,860 bytes)
- 3. [AMPS] PA-77 musings (score: 1)
- Author: N7CXI@SiliconPixels.com (Jim Barber)
- Date: Mon, 28 May 2001 02:55:54 -0700
- Rich, .. Agreed. I'm tempted to rebuild the original board just to be able to look at it with the spectrum analyzer, but it probably isn't worth the trouble. My DSO/analyzer only goes to 16mhz anyway
- /archives//html/Amps/2001-05/msg00474.html (9,051 bytes)
- 4. [AMPS] PA-77 musings (score: 1)
- Author: philk5pc@tyler.net (Phil Clements)
- Date: Mon, 28 May 2001 05:06:30 -0500
- . Okay, then make it 3900/3510 . I found the CC curve sheet for the 8877 on a site somewhere, but have no idea what idling current (thus first-approximation bias voltage) Eimac recommends for a 8877
- /archives//html/Amps/2001-05/msg00475.html (7,554 bytes)
- 5. [AMPS] PA-77 musings (score: 1)
- Author: drkirkby@ntlworld.com (David Kirkby)
- Date: Mon, 28 May 2001 11:27:46 +0100
- There's an 8877 data sheet on my site at http://www.david-kirkby.co.uk Just follow the links to ham and tube data bits - it should be obvious. -- Dr. David Kirkby Ph.D, email: drkirkby@ntlworld.com f
- /archives//html/Amps/2001-05/msg00476.html (8,537 bytes)
- 6. [AMPS] PA-77 musings (score: 1)
- Author: N7CXI@SiliconPixels.com (Jim Barber)
- Date: Mon, 28 May 2001 03:45:19 -0700
- Phil, Thanks. I was guessing 12V, (and remember seeing a confirming design somewhere) and that helps. Do you use a transistor switch, or a relay? I ask because of the voltage drop across the transist
- /archives//html/Amps/2001-05/msg00477.html (7,721 bytes)
- 7. [AMPS] PA-77 musings (score: 1)
- Author: 2@vc.net (2)
- Date: Mon, 28 May 2001 06:55:19 -0700
- ? JIM ? agreed. The feculence that is generated by RF bias switching is hard to see on a typical spectrum analyzer due to lack of skirt selectivity. A double-filter SSB receiver works quite well in
- /archives//html/Amps/2001-05/msg00480.html (9,851 bytes)
- 8. [AMPS] PA-77 musings (score: 1)
- Author: na9d@speakeasy.net (Jon Ogden)
- Date: Tue, 29 May 2001 07:07:51 -0500
- Rich's switching circuitry works absolutely outstandingly well! Your vacuum variable in the amp is probably sufficient or better than an RJ1-A. One minor correction that I would add to Rich's circuit
- /archives//html/Amps/2001-05/msg00488.html (8,739 bytes)
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