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21. [Amps] LP filter effects (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Mon, 18 Nov 2002 11:15:25 +0000; In theory, yes. In practice, it's often difficult to measure anything. Steve; /archives//html/Amps/2002-11/msg00305.html (8,167 bytes)
22. Fw: [Amps] LP filter effects (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Mon, 18 Nov 2002 11:17:28 +0000; I think it would have to be reasonably close to, or lower than, the signal frequency for 100W ish to get through the tank circuit and reach the o/p connector. Steve; /archives//html/Amps/2002-11/msg00306.html (7,733 bytes)
23. [Amps] Solid state amp advice needed (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Mon, 25 Nov 2002 10:14:37 +0000; Sounds like the sort of thing that might easily cause Vic's problem. Another area to check is any r/l/c feedback round the transistors, and also the supply decoupling. Faults in either could cause de; /archives//html/Amps/2002-11/msg00361.html (8,375 bytes)
24. [Amps] Solid state amp advice needed (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Tue, 26 Nov 2002 16:17:28 +0000; It's usually capacitor 'failure'. Unless the set is so old that electrolytics might have dried out, the most likely cause in my experience is a broken chip (probably mechanical cause) or dud solder j; /archives//html/Amps/2002-11/msg00374.html (9,337 bytes)
25. [Amps] skin effect (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Fri, 4 Oct 2002 21:41:38 +0100; The longwave guys certainly love it - the key point is that the strands are insulated from each other. A lot of stranded wire is multiple cores of tinned copper - skin effect means that, at hf upward; /archives//html/Amps/2002-10/msg00030.html (8,212 bytes)
26. [Amps] skin effect (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Fri, 4 Oct 2002 22:41:47 +0100; skin **Ok thanks. **Insulated--ok, this is starting to make some sense. like **I'm not sure what some of them are comparing. hi hi **Ok on the tin being lossier than copper, but tin or copper regular; /archives//html/Amps/2002-10/msg00033.html (9,308 bytes)
27. [Amps] skin effect (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Sat, 5 Oct 2002 08:42:02 +0100; At longwave I think the actual skin depth comes into play as well - it's around .15mm/.005" so if the individual strands in a bundle are too thin, you lose out. A useful place for UK readers - www.wi; /archives//html/Amps/2002-10/msg00038.html (8,899 bytes)
28. [Amps] skin effect (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Sat, 5 Oct 2002 08:44:56 +0100; simple the That was my thought, with the advantage that multistrand was much easier to handle and fashion into a coil. It certainly didn't work like that, and the enamel was well and truely fried off; /archives//html/Amps/2002-10/msg00039.html (8,395 bytes)
29. [Amps] Failed 8877 (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Mon, 7 Oct 2002 07:57:59 +0100; DVM, with filament 25% I have a pair of 8877s that do just the same - they come from the 'quality problem' period and came from industrial generator pulls, but I know nothing else of their history. I; /archives//html/Amps/2002-10/msg00054.html (8,500 bytes)
30. [Amps] Failed 8877 (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Mon, 7 Oct 2002 13:04:01 +0000; Sorry, but I don't know and my contact is long gone, so I've no route to find out. Steve; /archives//html/Amps/2002-10/msg00055.html (6,800 bytes)
31. [Amps] Failed 8877 (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Mon, 7 Oct 2002 20:21:20 +0100; then open moment. nothing heater 24hr been Something I should add here, just remembered. I tested both tubes in a 6m PA built by a friend - one tube ran up just like his, stacks of output without any; /archives//html/Amps/2002-10/msg00056.html (9,065 bytes)
32. [Amps] Failed 8877 (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Tue, 8 Oct 2002 12:35:47 +0000; I just dug them out - I can't hear the tinkling noises that I remember from before and one of them is going open when inverted. I never tried to correlate the noise to heater continuity - at the time; /archives//html/Amps/2002-10/msg00070.html (7,173 bytes)
33. [Amps] gg input (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Fri, 11 Oct 2002 23:25:22 +0100; In solid state amps it's seen as good practice to have a narrower bandwidth on the input than the output - avoids driving the amp where the device doesn't have a decent load, and saves expensive tran; /archives//html/Amps/2002-10/msg00109.html (7,252 bytes)
34. Fw: [Amps] How light can you make a 500W amplifier? (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Tue, 15 Oct 2002 08:16:48 +0100; Hz nearly a power Many years ago there was a design in a UK magazine using 3 x 4CX250s with voltage quadrupling off 240V mains - arranged to give +/- 700V so as to minimise the voltage offset to grou; /archives//html/Amps/2002-10/msg00139.html (9,337 bytes)
35. [Amps] Solid State (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Wed, 16 Oct 2002 13:58:43 +0000; Many of these problems can be caused by poor bias circuits, no harmonic filtering, and simply running the devices well beyond their linear capability. You could also have some fun learning about SS a; /archives//html/Amps/2002-10/msg00168.html (7,115 bytes)
36. [Amps] RE: Amps digest, Vol 1 #340 - 18 msgs (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Wed, 16 Oct 2002 18:04:45 +0000; What were the 3rd harmonic levels on 160m and 80m? Thanks Steve; /archives//html/Amps/2002-10/msg00177.html (7,475 bytes)
37. [Amps] Bird 1000H slug adjustment? (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Sun, 27 Oct 2002 09:20:14 -0000; If it's that far out it might need repairing rather than adjusting. Steve; /archives//html/Amps/2002-10/msg00278.html (8,111 bytes)
38. [Amps] Bird 1000H slug adjustment? (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Sun, 27 Oct 2002 16:24:19 +0000; Agreed. In V/UHF slugs, the diode is a UHF germanium type and I've had good success replacing it with a low barrier shottky. In these slugs, there's a series resistor for cal, typically 25-30k. Even; /archives//html/Amps/2002-10/msg00282.html (8,467 bytes)
39. [Amps] Bird 1000H slug adjustment? (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Mon, 28 Oct 2002 09:20:59 +0000; If you measure the V/I characteristic of the good slug, and assume the internal resistor is the same value as the one you have, you could get an idea of the diode turn-on voltage, and look for a simi; /archives//html/Amps/2002-10/msg00290.html (8,340 bytes)
40. [Amps] Distortion (score: 1): Author: g8gsq@qsl.net (Steve Thompson); Date: Tue, 29 Oct 2002 17:15:35 +0000; You design and tune up for maximum required output power, and live with reduced efficiency at lower output powers. Steve; /archives//html/Amps/2002-10/msg00303.html (6,876 bytes)

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