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1. [Amps] Subharmonic (score: 1): Author: g4piq@btinternet.com (Andy Cook, G4PIQ); Date: Wed, 22 May 2002 12:46:25 +0100; I've been watching this topic with interest. I can't add anything from a detailed technical perspective to the discussion, but I can say that perhaps it's not so un-common. During one contest I had m; /archives//html/Amps/2002-05/msg00350.html (7,988 bytes)
2. [AMPS] Need AL-811 Schematic (score: 1): Author: g4piq@btinternet.com (Andy Cook, G4PIQ); Date: Mon, 12 Nov 2001 14:14:21 +0000; Can anyone help me with an scanned copy of the 3 tube AL-811 amp. About to leave for XT2 for CQWW CW at the end of the week and we have a couple of AL-811s out there as spare amps which need a little; /archives//html/Amps/2001-11/msg00190.html (6,732 bytes)
3. [AMPS] AL-1500, AL-82, AL-1200, QRO??? (score: 1): Author: g4piq@btinternet.com" <g4piq@btinternet.com (Andy Cook, G4PIQ); Date: Tue, 16 Jan 2001 12:11:10 -0000; I'd just like to counter that by saying that in 15 years of looking after the amps for our multi-multi contest group the ONLY fatal tube failures which I have seen have been 2 grid-filament shorts in; /archives//html/Amps/2001-01/msg00375.html (9,984 bytes)
4. [AMPS] AL-1500, AL-82, AL-1200, QRO??? (score: 1): Author: g4piq@btinternet.com" <g4piq@btinternet.com (Andy Cook, G4PIQ); Date: Tue, 16 Jan 2001 22:52:10 -0000; Yes. The amplifier is a Henry and has a 25 ohm resistor (+ diode) in the path between the -ve side of the filter capacitor and ground. This may well be true - it seems a solid tube with high grid dis; /archives//html/Amps/2001-01/msg00401.html (10,515 bytes)
5. [AMPS] AL-1500, AL-82, AL-1200, QRO??? (score: 1): Author: g4piq@btinternet.com" <g4piq@btinternet.com (Andy Cook, G4PIQ); Date: Wed, 17 Jan 2001 10:42:24 -0000; Piece of education needed for me here. The glitch resistor is there to limit fault current in event of a flash-over. The only source of these big currents is from the filter capacitor and the only ro; /archives//html/Amps/2001-01/msg00408.html (9,937 bytes)
6. Re: [Amps] 8877 grid current going negative etc (score: 1): Author: "Andy Cook, G4PIQ" <g4piq@btinternet.com>; Date: Wed, 7 Dec 2005 11:56:04 -0000; Ian, It's probably either a grid cathode short in the tube (which can be temperature related), but also check for any swarf etc. stuck between the vanes of the input tuning cap on the cathode if it h; /archives//html/Amps/2005-12/msg00057.html (6,678 bytes)
7. [Amps] Applying drive to a cold tube (score: 1): Author: ANDY COOK <g4piq@btinternet.com>; Date: Wed, 24 Jun 2009 10:43:44 +0000 (GMT); Is there any problem with applying full drive (30W) to a completely cold and powered down 3CX800 for extended periods? We all know about the cathode damage issues from applying drive to a powered-up; /archives//html/Amps/2009-06/msg00106.html (6,526 bytes)
8. [Amps] TenTec Titan 425 Idle Grid Current (score: 1): Author: ANDY COOK <g4piq@btinternet.com>; Date: Thu, 27 Sep 2012 13:06:40 +0100 (BST); Mark, Although grid current in a triode amp may not be 'normal' under no drive conditions, I have always seen a few mA indicated on the many Titan 425s which I've used as you go to transmit. It may; /archives//html/Amps/2012-09/msg00304.html (8,089 bytes)
9. Re: [Amps] 425 Amp (score: 1): Author: "Andy Cook, G4PIQ" <g4piq@btinternet.com>; Date: Thu, 4 Apr 2013 11:06:24 +0100; drive Do check the HV filter capacitors which will are very suspect by this age of amp. I've found that when they fail, the overdrive light comes on with just a few watts of drive but not with the n; /archives//html/Amps/2013-04/msg00017.html (7,666 bytes)
10. Re: [Amps] Alpha 76 "SNAP" noise (score: 1): Author: "Andy Cook, G4PIQ" <g4piq@btinternet.com>; Date: Tue, 23 Dec 2014 11:08:02 +0000; Oh yes. I heard this coming from one of our old Alpha 78s during CQWW CW at 5U5Z some years ago. It did this for quite a few hours and then in the middle of the night there was a big bang and the roo; /archives//html/Amps/2014-12/msg00082.html (6,910 bytes)

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