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21. [Amps] 8877 failures and GE Medical (score: 1): Author: peter.chadwick at Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Tue Mar 4 03:49:27 2003; manufacturing would know. Even small >receiving tubes operating in low-voltage systems were the most likely components to fail in old tube I suspect one problem is that a lot of manufacturing 'know h; /archives//html/Amps/2003-03/msg00087.html (7,917 bytes)
22. [Amps] Why hasn't solid state replaced tubes? (score: 1): Author: peter.chadwick at Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Tue Mar 4 07:49:26 2003; tells This is probably because the International Radio Regulations don't call close in IMD 'spurious emissions' either. In professional circles, they are called 'Out of Band Emissions'. Out of Band e; /archives//html/Amps/2003-03/msg00093.html (9,629 bytes)
23. [Amps] Why hasn't solid state replaced tubes? (score: 1): Author: peter.chadwick at Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Tue Mar 4 09:13:52 2003; Maritime specifications required -31dB rel PEP or -25dB rel tone at the full output. A number of commercial HF rigs in the 100 watt class that I was involved with were rated at -28dB rel PEP: they we; /archives//html/Amps/2003-03/msg00100.html (9,611 bytes)
24. [Amps] Why hasn't solid state replaced tubes? (score: 1): Author: peter.chadwick at Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Fri Mar 7 05:20:00 2003; It is interesting that in landline SSB, IMD was measured by loading the channel with a noise signal: this had a 'slot' in the spectrum with no noise in it, and the IMD was measured as the amount of n; /archives//html/Amps/2003-03/msg00291.html (9,485 bytes)
25. [Amps] Re: COLLINS Engineering (score: 1): Author: peter.chadwick at Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Mon Mar 24 04:59:36 2003; of Take your pick from Marconi, Racal, Redifon, Plessey (only up to about 1kW at HF), STC. Racal and Marconi and STC were big in the point to point stuff. Marconi were for a long time the naval suppl; /archives//html/Amps/2003-03/msg00806.html (7,658 bytes)
26. [Amps] HT power supplies? (score: 1): Author: peter.chadwick at Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Mon Mar 24 12:38:30 2003; Have you checked the actual resonant frequency? My understanding of the tuned choke filter is that it should be tuned slightly higher in frequency. This makes the circuit look like a very much bigger; /archives//html/Amps/2003-03/msg00813.html (7,385 bytes)
27. [Amps] Filament Inrush Control (score: 1): Author: peter.chadwick at Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Wed Mar 26 04:54:42 2003; I guess from that you don't have any YL contest ops down there! Considering the operating abilities of some of the YL ops (such as Ann, WA1S, who really is a superb contest and DXpedition operator) t; /archives//html/Amps/2003-03/msg00838.html (8,529 bytes)
28. [Amps] Parasites (parasitics) (score: 1): Author: peter.chadwick at Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Thu Mar 27 11:27:35 2003; Just to complicate the issue, I've seen a number of transmitters where very effective parasitic suppression was achieved with a 100 ohm 50 watt carbon stick resistor sitting with one end attached to; /archives//html/Amps/2003-03/msg00873.html (8,648 bytes)
29. [Amps] Parasites (parasitics) (score: 1): Author: peter.chadwick at Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Fri Mar 28 04:28:21 2003; If the plate circuit is tuned lower in frequency than the grid circuit, then it doesn't matter how much feedback capacity there is, the tube cannot oscillate. See Mr. Terman on the subject. Which is; /archives//html/Amps/2003-03/msg00903.html (8,032 bytes)
30. [Amps] 100 Watt WW resistor Voltages (score: 1): Author: peter.chadwick at Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Tue Feb 4 11:52:01 2003; I've used a 100k vitreous enamelled w/w that is about 14 inches long at 3500v for some years, with no problems. I think it's about 150 or 200 watts: it's 1.5inches in diameter. 73 Peter G3RZP; /archives//html/Amps/2003-02/msg00072.html (6,740 bytes)
31. [Amps] Yaesu FL-1000 (score: 1): Author: peter.chadwick at Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Fri Feb 28 07:37:09 2003; My father had one. It's a carcass on the floor of the workshop at the moment, awaiting resurrection - as it has been for about 17 years! A weakness is the variability of 6JS6s. They need a separate b; /archives//html/Amps/2003-02/msg00508.html (7,327 bytes)
32. [Amps] T'bolt ideas (score: 1): Author: peter.chadwick@Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Tue, 14 Jan 2003 08:13:41 +0000; Not necesarily. But you do need a well regulated screen supply, a 'stiff' bias supply that doesn't move with grid current (mine moves under 50millivolts), some RF NFB in the filament circuit, and abo; /archives//html/Amps/2003-01/msg00105.html (7,650 bytes)
33. [Amps] Re: Thunderbolt (score: 1): Author: peter.chadwick@Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Tue, 14 Jan 2003 08:29:15 +0000; There is no such thing as a perfect commercially mfg amplifier. Quite right! If there was, nobody could afford it - not even Uncle Sam! 73 Peter G3RZP; /archives//html/Amps/2003-01/msg00106.html (7,109 bytes)
34. [Amps] T'bolt ideas (score: 1): Author: peter.chadwick@Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Tue, 14 Jan 2003 12:38:25 +0000; Pappenfus et al. (and even Eimac) explain why the curvature produced by grid current in AB2 can cancel IMD. But it won't do it in 4-400s without proper circuitry in terms of NFB and regulated supplie; /archives//html/Amps/2003-01/msg00109.html (8,208 bytes)
35. [Amps] re Negative lead filtering (score: 1): Author: peter.chadwick@Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Mon, 2 Dec 2002 08:12:40 +0000; Negative lead filtering works very well. I rectify the volts across the choke in the screen supply to get the bias: the choke is tuned, too. It; /archives//html/Amps/2002-12/msg00019.html (6,864 bytes)
36. [Amps] re Negative lead filtering (score: 1): Author: peter.chadwick@Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Mon, 2 Dec 2002 08:14:29 +0000; Negative lead filtering works very well. I rectify the volts across the choke in the screen supply to get the bias: the choke is tuned, too. It does need a regulator, though. I suspect that if you us; /archives//html/Amps/2002-12/msg00020.html (7,045 bytes)
37. [Amps] MFJ inrush current protector? (score: 1): Author: peter.chadwick@Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Mon, 2 Dec 2002 15:58:02 +0000; the My experience is that they aren't cheap, either. Although I guess it's a truism that you you don't always get what you pay for, but you very rarely get what you don't pay for. If you want energy; /archives//html/Amps/2002-12/msg00029.html (7,530 bytes)
38. [Amps] Q: Chimneys for 3-500/4-400?? (score: 1): Author: peter.chadwick@Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Wed, 4 Dec 2002 08:22:41 +0000; One military transmitter used QY4-250's (which are very similar to 4-250A's, but without the metal base ring) and thus not that different to 4-400's, but only blew from the top - a big (8inch diamete; /archives//html/Amps/2002-12/msg00055.html (8,305 bytes)
39. [Amps] (no subject) (score: 1): Author: peter.chadwick@Zarlink.Com (peter.chadwick@Zarlink.Com); Date: Wed, 11 Dec 2002 09:01:29 +0100; Are any of the Swedish hams still reading the reflector?I'm in Stockholm and free on Friday evening and Saturday. I can be contacted at peter.chadwick@ieee.org. 73 Peter G3RZP; /archives//html/Amps/2002-12/msg00161.html (7,107 bytes)
40. [Amps] 4-400A Plate (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Mon, 11 Nov 2002 12:28:43 -0000; The most impressive glowing plates I've ever seen were 35T triodes. The tantalum plate would (properly) be run so hot (white!) that you could see the shadow of the grid wires through it, illuminated; /archives//html/Amps/2002-11/msg00165.html (8,352 bytes)

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