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121. [Amps] Reposting subject line, oops, there i go again (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Sat, 03 Apr 2010 11:52:14 -0600; When I hit reply in two different emailers, it puts in the subject line "RE: Amps Digest, Vol xx, Issue yy" (fill in the numbers). I use the digest mode to reduce constant emailing bings on my comput; /archives//html/Amps/2010-04/msg00045.html (7,437 bytes)
122. [Amps] STUBS, subject name may have changed (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Sat, 03 Apr 2010 12:26:37 -0600; I know it may not apply to 99% of the cases here, but my interest is STUBS - the ones made with rigid transmission line, at QRO+ levels. This is why I asked a question here a week ago as there are so; /archives//html/Amps/2010-04/msg00051.html (12,773 bytes)
123. Re: [Amps] Reposting subject line, oops, there i go again (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Sat, 03 Apr 2010 12:57:27 -0600; Thanks Bill, that is constructive advice. I will look into doing it, for home (Thunderbird). However, I am not certain it will work in the important location, at the salt mine, as I use a different p; /archives//html/Amps/2010-04/msg00054.html (9,544 bytes)
124. [Amps] Liquid Cooling (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Mon, 5 Apr 2010 11:33:59 -0600; At work we use oil cooling for a number of situations with high voltage. The oil gives a great benefit for insulation and allows more compact layouts. I don't know of any RF amplifiers this way, only; /archives//html/Amps/2010-04/msg00103.html (9,621 bytes)
125. [Amps] contact bounce (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Mon, 5 Apr 2010 16:34:35 -0600; Don, k4kyv, wrote a good description of how he tackled sequencing, for old buzzard AM stations, in the following: http://amfone.net/Amforum/index.php?topic=6211.0 Maybe something there that can be le; /archives//html/Amps/2010-04/msg00133.html (10,029 bytes)
126. [Amps] Liquid Cooling (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Tue, 6 Apr 2010 09:54:14 -0600; The 200-400 uA leakage is excellent, within the recommendations of CPI/Eimac for their H2O cooled tubes. Your Russian tubes should last a long time if the emission is strong. I use water cooling in 1; /archives//html/Amps/2010-04/msg00152.html (9,178 bytes)
127. [Amps] IGBT-controlled grid voltage (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Thu, 15 Apr 2010 12:57:46 -0600; Using the TH628 tetrode-style tube in my amplifier project, I need to pulse the control grid in and out of conduction for the repetition rate of my amplifier. This is because the plate dissipation is; /archives//html/Amps/2010-04/msg00473.html (7,681 bytes)
128. [Amps] V. O. Stokes book obtained (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Tue, 27 Apr 2010 20:18:26 -0600; I got a copy, it wasn't cheap and it appears to have been in a very damp environment for a long time. So it is musky smelling. What should I do to freshen up this classic book so that I feel like rea; /archives//html/Amps/2010-04/msg00681.html (7,485 bytes)
129. [Amps] contaminated V.O.Stokes book (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Fri, 30 Apr 2010 13:21:19 -0600; Thanks, all, for your advice. I tried a simple approach last night, I zipped the Stokes transmitter book in a large baggie with a quantity of sodium bicarbonate, and changed it once with fresh powder; /archives//html/Amps/2010-04/msg00712.html (6,750 bytes)
130. [Amps] 5CX1500A (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Fri, 7 May 2010 17:43:00 -0600; This tube was also used in Collins 2.5 kW FM broadcast transmitters. Many are probably still in service in smaller stations. I worked on one in college days. There was a reliability problem related t; /archives//html/Amps/2010-05/msg00107.html (7,806 bytes)
131. [Amps] Rebuilding oxide cathode tubes (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Tue, 6 Jul 2010 15:19:24 -0600; I believe the answer is that thoriated tungsten filaments are much easier to copy and replace, than oxide cathodes. Its my impression that calcium, barium, strontium oxide chemistry is somewhat propr; /archives//html/Amps/2010-07/msg00064.html (10,544 bytes)
132. [Amps] large tubes in VHF service, tetrode p. suppressors (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Thu, 15 Jul 2010 22:24:54 -0600; I built 5 kW class C power amplifiers using the 4CX5000A and 4CX3000A on 108 MHz broadcast. Both were used in the industry for years (RCA) but were terrible compared to the short Eimac 4CX3500A. They; /archives//html/Amps/2010-07/msg00146.html (7,500 bytes)
133. [Amps] parasitic suppressor voodoo (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Fri, 16 Jul 2010 12:30:00 -0600; I try to stay out of these discussions but this reply was spot on: -- Date: Fri, 16 Jul 2010 13:20:37 +0100 From: Dave White <mausoptik@btinternet.com> Subject: Re: [Amps] parasitic suppressor voodoo; /archives//html/Amps/2010-07/msg00180.html (13,047 bytes)
134. [Amps] PS (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Fri, 30 Jul 2010 11:37:38 -0600; Amen... Years ago (20) I got into an argument with a respected experienced and seasoned RF oscillator designer (making dielectric heating machines) of equipment that was 10 kW and up, in the HF to VH; /archives//html/Amps/2010-07/msg00355.html (9,341 bytes)
135. [Amps] big PS (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Fri, 30 Jul 2010 18:31:57 -0600; This is the final power, the driver is 14 kV at 25 amps. I don't have a key for it, only a PLC command on a screen to energize it. Cannot send morse with it, not fast enough, unless i key a pin diode; /archives//html/Amps/2010-07/msg00366.html (8,454 bytes)
136. [Amps] soft start on filament (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Sun, 29 Aug 2010 11:22:07 -0600; Commercially, what is usually done to protect thoriated-tungsten filaments (for tubes with handles) from excess inrush current is to limit the current to no more than 2 X the rated current at nominal; /archives//html/Amps/2010-08/msg00441.html (9,523 bytes)
137. [Amps] soft start on filament (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Sun, 29 Aug 2010 14:26:18 -0600; No I mean a transformer that is designed with shunt or gap, I cannot remember how it is done. Basically the filament transformer will not go beyond 2 X the normal current without voltage falling off.; /archives//html/Amps/2010-08/msg00444.html (9,483 bytes)
138. [Amps] Holes vs. screen for chassis ventilation? (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Wed, 6 Oct 2010 09:39:58 -0600; For high power HF and VHF amplifiers where I need to pass air through a hole, I have been using copper hardware cloth, sold by McMaster Carr, instead of aluminum screening. It is made from heavy copp; /archives//html/Amps/2010-10/msg00054.html (8,755 bytes)
139. [Amps] Switching Supplies for High Current Filaments (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Thu, 7 Oct 2010 13:05:40 -0600; I am using a switcher to power the filament for a TH781 tetrode, as a driver for a TH628 Diacrode final PA. The tetrode needs 9.5 VDC at 325 Amps, and the switcher works very well. I was nervous doin; /archives//html/Amps/2010-10/msg00104.html (9,795 bytes)
140. [Amps] loss of cooling interlock (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Mon, 8 Nov 2010 11:25:23 -0700; I ran a 4CX1000A at 100 MHz, 1.5 kW CW, with a plugged cooling duct years ago. It started drifting out of tune, and eventually baked some of the nickle plating to a dark tarnish. It was still working; /archives//html/Amps/2010-11/msg00047.html (7,597 bytes)

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