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1. [Amps] George Badger, W6TC (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Wed, 18 Nov 2009 13:13:56 -0700; George was a FB OM. He and I worked together as supplier and customer over the years also. When the new 4CX3500A came out, he convinced me to make the first non-Eimac VHF cavity amplifier of this tub; /archives//html/Amps/2009-11/msg00200.html (8,114 bytes)
2. [Amps] Dimished Tube Life versus emission (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Fri, 25 Sep 2009 10:32:29 -0600; This reply is based on my own experience, plus talking to various tube manufacturers over the years, dealing with larger power tubes. Emission lifetime, of course, depends a lot on how the tube was s; /archives//html/Amps/2009-09/msg00315.html (12,226 bytes)
3. [Amps] Vacuum variable hipotting (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Fri, 18 Sep 2009 15:39:45 -0600; Yes, you aren't really cooking the vacuum, you are 'spark knocking' the device. By applying controlled HV, the pesky whiskers that tend to cause sparkovers inside the device will be emitting electron; /archives//html/Amps/2009-09/msg00244.html (8,191 bytes)
4. [Amps] 304TH, 304TL, 813 (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Mon, 07 Sep 2009 08:37:11 -0600; I picked up an old copy of Don Stoner's (W6TNS) New Sideband Handbook, dated 1958, CQ Technical Series, at a hamfest last month. Interesting reading, the Heathkit SB10 adapter was hot stuff then, alo; /archives//html/Amps/2009-09/msg00068.html (9,522 bytes)
5. [Amps] DC versus AC filament power (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Thu, 03 Sep 2009 23:36:47 -0600; Bill is spot on with his explanation here. In bigger tubes it even becomes less of a problem, of having nonuniform electron flow in a tube for a particularly biased filament. This is because the frac; /archives//html/Amps/2009-09/msg00037.html (8,220 bytes)
6. [Amps] "noninductive" resistors (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Thu, 03 Sep 2009 23:30:31 -0600; Have to be careful when using "non inductive" style resistors such as listed here, for RF service. As was pointed out, watch for the spiral grooved film resistors. But many of the others that say "no; /archives//html/Amps/2009-09/msg00036.html (9,942 bytes)
7. [Amps] Loaded output circuits (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Sun, 30 Aug 2009 22:41:41 -0600; Thanks, Gary, for explaining that so eloquently. I think yours is the most understandable reply. It should make sense to all AMPS listers. 73 John K5PRO -- ___________________________________________; /archives//html/Amps/2009-08/msg00652.html (7,275 bytes)
8. [Amps] Loaded output circuits (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Sun, 30 Aug 2009 11:27:39 -0600; W4TV posted a satisfactory explanation of why the circulating current goes up with Q in a high powered output circuit. This is fundamental to understanding the trade-offs in high power amplifier desi; /archives//html/Amps/2009-08/msg00639.html (9,303 bytes)
9. [Amps] TH347 filament ramping (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Fri, 28 Aug 2009 16:52:31 -0600; Yes, that's one expensive but fantastic performing tube. I was looking at using it in 1993, for 2 KW CW at 805 MHz, when RCA/Burle pulled the plug on manufacturing the 8501 Cermelox tetrode, which wa; /archives//html/Amps/2009-08/msg00589.html (9,315 bytes)
10. [Amps] TH347 filament ramping (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Fri, 28 Aug 2009 15:03:24 -0600; Gerald, that's unfortunate, I hope you didn't pay list price for those tubes and have them fail like that. Your relay scheme seems like it would have prevented problems. Did the filaments burn out or; /archives//html/Amps/2009-08/msg00583.html (7,401 bytes)
11. [Amps] Not the Diacrode (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Fri, 28 Aug 2009 14:59:38 -0600; Neat idea, once you figure out the size of the iron. I didn't know that an overloaded ferroresonant transformer would drop voltage that much (to a few % of nominal line voltage). I suppose there migh; /archives//html/Amps/2009-08/msg00582.html (9,816 bytes)
12. [Amps] Not the Diacrode (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Fri, 28 Aug 2009 09:31:21 -0600; The filament is DC powered. De big tubes often use DC as the filament may mechanically resonate with powerline frequency and short to grid or itself. I heard and old story of Radio France having a pr; /archives//html/Amps/2009-08/msg00576.html (8,208 bytes)
13. [Amps] Not the Diacrode (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Thu, 27 Aug 2009 19:38:00 -0600; The Diacrode is a decent high power UHF tube, it is a double-ended tetrode, but it has the same transit time effects as a similar "bottom" circuited tetrode. It merely allows placement in the center; /archives//html/Amps/2009-08/msg00564.html (7,628 bytes)
14. [Amps] Running iron in oil (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Thu, 27 Aug 2009 14:46:26 -0600; At work we have dozens of tanked transformers in use. Being at 7000 feet above sea level, with high voltages, made it a requirement for some systems. They have been running for 40 years this way. We; /archives//html/Amps/2009-08/msg00554.html (8,762 bytes)
15. [Amps] Tube gain vs frequency (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Thu, 27 Aug 2009 11:14:06 -0600; Alex and Gerald pretty much gave you replies that explained this. Here is more 'free' information. Usually the output circuit is the most difficult to design as you push tubes in Power x Freq. Output; /archives//html/Amps/2009-08/msg00551.html (12,837 bytes)
16. [Amps] PL259 connectors for LDF4 Heliax (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Wed, 26 Aug 2009 14:05:01 -0600; I am probably repeating info that was already posted, but I see that RF Industries has a replacement male and female UHF connector for Andrew LDF4-50, and RFS LCF12-50 cables (1/2 inch diameter Helia; /archives//html/Amps/2009-08/msg00512.html (6,994 bytes)
17. [Amps] parasitic oscillation techniques (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Sun, 23 Aug 2009 10:15:42 -0600; The discussion of they what, why and how of parasitic suppression has always been controversial on this forum, especially when AG6K was here with his own retrofit kits and QST articles. I think there; /archives//html/Amps/2009-08/msg00410.html (12,609 bytes)
18. [Amps] PIN diodes and QSK (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Fri, 7 Aug 2009 09:30:28 -0600; Thanks, Lon, k5jv, for the work on PIN diodes that you reported.. Makes me think the same thing, why pay for the $$ diodes if silicon power rectifiers will do? 73 john K5PRO New Mexico ______________; /archives//html/Amps/2009-08/msg00129.html (7,003 bytes)
19. [Amps] RF 103A plate transformer (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Fri, 24 Jul 2009 09:24:05 -0600; Since that amplifier uses a conventional choke input filter for the HV power supply, and the DC voltage is marked as 3300 VDC on the schematic, one would assume that the transformer RMS rating is 350; /archives//html/Amps/2009-07/msg00323.html (7,827 bytes)
20. Re: [Amps] Gettering 572B (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Tue, 23 Jun 2009 07:36:57 -0600; Bill Sounds like some internet 'folklore' has become interjected with conditioning of large power tubes. With large tubes, it is imperative to condition them before first use, and if they sit for a l; /archives//html/Amps/2009-06/msg00097.html (12,605 bytes)

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