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1. [Amps] Alpha 78 problem (score: 1): Author: Carsten.Esch at APPELLO.DE (Carsten Esch); Date: Wed Jul 16 08:26:24 2003; Hi, just returned from Albania where there is an Alpha 78. This amp has a problem. When you turn the amp on, there is a huge insertion loss on receive (like the amp would be in operate mode immediate; /archives//html/Amps/2003-07/msg00083.html (6,658 bytes)
2. [Amps] Alpha 78 problem (score: 1): Author: 2 at vc.net (2); Date: Thu Jul 17 08:13:41 2003; ** I would check the input reed-relay first off. If it's bad, the Matsushita RSD RF reed relay is an upgrade since it has Rh-Au contacts. In single-lots, these relays cost $11 ea. Rich, AG6K, 805-38; /archives//html/Amps/2003-07/msg00090.html (7,145 bytes)
3. [AMPS] Alpha 78 problem (score: 1): Author: carsten.esch@olympus-software.com (Carsten Esch); Date: Fri, 09 Oct 1998 15:24:35 +0100; Hi, D44BC got a problem with his Alpha 78 amplifier, maybe some of yourguys can help us to guess what could cause this problem: When switching the amp ok evrything is ok. As soon as you apply drive,; /archives//html/Amps/1998-10/msg00071.html (7,420 bytes)
4. [AMPS] Alpha 78 problem (score: 1): Author: measures@vc.net (Rich Measures); Date: Fri, 9 Oct 98 07:18:06 -0800; I would check each tube [cold] with a high-potential tester. If the anode/grid leakage is over roughly 10uA @ 5000v, it is not good news. If the leakage current decreases substantially with neg. pol; /archives//html/Amps/1998-10/msg00072.html (7,598 bytes)
5. [AMPS] Alpha 78 problem (score: 1): Author: km1h@juno.com (km1h@juno.com); Date: Fri, 9 Oct 1998 12:32:48 -0400; Lacking a HV tester you can try with one tube at a time and go from there. It is unlikely that both tubes will share the same failure. Many contesters have limped along on one tube....just keep the d; /archives//html/Amps/1998-10/msg00076.html (8,950 bytes)
6. [AMPS] Alpha 78 problem (score: 1): Author: aa7bg@3rivers.net (K7BG Matt Trott); Date: Sat, 10 Oct 1998 00:15:47 -0600 (MDT); There's a wirewound resistor in front of the xfrmr. Actually there are three of them. THey can open when hot and cause the amp to shut off. I think the one that went bad in my 374A was a 15w 10 ohm.; /archives//html/Amps/1998-10/msg00082.html (7,737 bytes)
7. [AMPS] Alpha 78 problem (score: 1): Author: w4eto@rmii.com (Richard W. Ehrhorn); Date: Sat, 10 Oct 1998 12:01:30 -0600; If I remember right there should be 10 ohms/25W on each side of the 240V line input. 73, Dick There's a wirewound resistor in front of the xfrmr. Actually there are three of them. THey can open when; /archives//html/Amps/1998-10/msg00091.html (8,459 bytes)
8. [Amps] Alpha 78 problem (score: 1): Author: "Carol Richards" <n2mm@comcast.net>; Date: Sat, 10 Nov 2007 10:45:18 -0500; Hello........ During the last contest I began to develop a problem. When I key the alpha, non qsk mode, everything is fine. When I let up on the key the amp continues to mute the receiver. If I tap o; /archives//html/Amps/2007-11/msg00131.html (7,351 bytes)
9. Re: [Amps] Alpha 78 problem (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Sat, 10 Nov 2007 07:54:06 -0800; I don't know that amp, but it may be a vacuum relay made by Jennings or Kilovac. Check the schematic/parts list. A company called Gigavac makes replacements for both, and sells them to hams at a nice; /archives//html/Amps/2007-11/msg00132.html (7,640 bytes)
10. Re: [Amps] Alpha 78 problem (score: 1): Author: "jeremy-ca" <km1h@jeremy.mv.com>; Date: Sat, 10 Nov 2007 10:54:38 -0500; I dont have the manuals handy but Id suspect that 15A ceramic fuses are sufficient on a 240VAC line. I use 12A in 1200W output amps. Carl KM1H _______________________________________________ Amps mai; /archives//html/Amps/2007-11/msg00133.html (7,920 bytes)
11. [Amps] Alpha 78 problem (score: 1): Author: "Carol Richards" <n2mm@comcast.net>; Date: Fri, 16 Nov 2007 22:14:56 -0500; Thank you to all who responded to my request for help with a relay problem...After speaking with the folks at Alpha Power, The conclusion was either a faulty reed relay ($125) of the vacuum relay($15; /archives//html/Amps/2007-11/msg00224.html (6,964 bytes)
12. Re: [Amps] Alpha 78 problem (score: 1): Author: "Carol Richards" <n2mm@comcast.net>; Date: Mon, 3 Dec 2007 20:23:01 -0500; Thanks Jim for the info.... _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps; /archives//html/Amps/2007-12/msg00014.html (7,828 bytes)
13. [Amps] Alpha 78 Problem (score: 1): Author: "isaonuma" <isaonuma@cablenet.ne.jp>; Date: Tue, 29 Dec 2009 20:08:48 +0900; Hello all, I have recently bought Alpha 78 and it's faily clean. I checked inside and seemed OK. So I connected 220V line and swithed on it. High voltage shows 1500V+ at CW, 2000V+ at SSB mode. Air f; /archives//html/Amps/2009-12/msg00554.html (7,005 bytes)
14. Re: [Amps] Alpha 78 Problem (score: 1): Author: k8mlm@aol.com; Date: Tue, 29 Dec 2009 17:05:25 -0500; Isao, The normal warm up time for the Alpha 78 is 3 minutes. However, dur to the age of the caps and/or carbom comp resistors in the timer circuit the timer may not work or take a long tome to turn o; /archives//html/Amps/2009-12/msg00558.html (8,235 bytes)
15. Re: [Amps] Alpha 78 Problem (score: 1): Author: Jim Barber <audioguy@charter.net>; Date: Tue, 29 Dec 2009 14:15:34 -0800; Apologies for hijacking the thread, but speaking of the Alpha 77 bias, is there a preferred method for defeating the "active" part? I remember seeing somewhere that some revs had a pot for adjusting; /archives//html/Amps/2009-12/msg00559.html (9,652 bytes)
16. Re: [Amps] Alpha 78 Problem (score: 1): Author: "Carl" <km1h@jeremy.mv.com>; Date: Tue, 29 Dec 2009 17:50:46 -0500; When the 77 was still in regular use it was easy to spot one by the splatter caused by the electronic bias spike. There has been a lot written about a fix. Carl KM1H _________________________________; /archives//html/Amps/2009-12/msg00560.html (10,350 bytes)
17. Re: [Amps] Alpha 78 Problem (score: 1): Author: Sugiyama <ji3kdh@2333.net>; Date: Wed, 30 Dec 2009 08:39:30 +0900; Isao-san, I also enjoy with the great amp PA-78. It's quiet and useful, you know. 1) You cannot hear the sound of K2, because it has only 100-200ms delay time. 2) You can see the green lamp when you; /archives//html/Amps/2009-12/msg00563.html (8,054 bytes)
18. Re: [Amps] Alpha 78 Problem (score: 1): Author: K8MLM@aol.com; Date: Tue, 29 Dec 2009 20:44:55 EST; Properly adjusted the electronic bias works fine... no chop, no splatter. I installed a pot to fine tune adjust mine. Bob K8MLM In a message dated 12/29/2009 5:51:22 P.M. Eastern Standard Time, km1h@; /archives//html/Amps/2009-12/msg00564.html (11,120 bytes)
19. [Amps] Alpha 78 Problem (score: 1): Author: "Isao Numaguchi" <isaonuma@cablenet.ne.jp>; Date: Wed, 30 Dec 2009 17:45:21 +0900; Hi, Bill Thanks for the tips, I will leave the CW/SSB buttons all out and see what happens. CUL de Isao/JH1ROJ _______________________________________________ Amps mailing list Amps@contesting.com ht; /archives//html/Amps/2009-12/msg00567.html (10,143 bytes)
20. Re: [Amps] Alpha 78 Problem (score: 1): Author: "Paul Christensen" <w9ac@arrl.net>; Date: Wed, 30 Dec 2009 07:58:22 -0500; I spoke with Ray Heaton about this back when I purchased my first 77Dx. On the Dx/Sx models, the EBS can be defeated by adjusting one potentiometer on the bias board. Plate idling current can be adj; /archives//html/Amps/2009-12/msg00569.html (8,501 bytes)

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