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81. [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)
82. [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)
83. [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)
84. [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)
85. [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)
86. [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)
87. [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)
88. [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)
89. [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)
90. [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)
91. [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)
92. [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)
93. [Amps] power meters for HF/VHF (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Wed, 02 Dec 2009 13:22:09 -0700; The Cantenna in question (70 ohms) is no good. As others said, replace the element, someone cooked it too hard. Dr. Dave K. is spot on, Bird 43 is not a laboratory instrument. Just a rough indicator.; /archives//html/Amps/2009-12/msg00042.html (8,661 bytes)
94. [Amps] Decent HF directional coupler for RF power meas. (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Wed, 02 Dec 2009 20:54:56 -0700; The best directional couplers that I have used for HF power are the Werlatone model C1460, rated for 2 kW through power, with -50 dB coupling (+/-0.5), from 0.01 - 250 MHz. Over the HF portion they h; /archives//html/Amps/2009-12/msg00066.html (7,636 bytes)
95. [Amps] Sources of Hot Sticks (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Thu, 10 Dec 2009 22:45:21 -0700; Salisbury (used to be White Safety Line) http://www.whsalisbury.com/additional_grounding/index.htm Ross Engineering http://www.rossengineeringcorp.com/grounding_rods.htm If you make your own, be sure; /archives//html/Amps/2009-12/msg00293.html (7,552 bytes)
96. [Amps] water cooling (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Thu, 17 Dec 2009 20:09:53 -0700; I would recommend to check into the datasheet for flow volume versus dissipation, if it is a well-spec'd tube. As for size of condensor, you are talking vapor cooling I guess. One good source of info; /archives//html/Amps/2009-12/msg00409.html (9,085 bytes)
97. [Amps] water conductivity and hose length (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Sat, 19 Dec 2009 12:43:39 -0700; Here is the exact method for determining the length of hose needed for a particular water cooling system having High Voltage DC across the hoses. This is how i do it for big amplifiers with high volt; /archives//html/Amps/2009-12/msg00497.html (8,792 bytes)
98. [Amps] water cooling tips (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Tue, 22 Dec 2009 13:58:13 -0700; Jim Tonne is correct, not only for the filter but for the bottles that clean up big cooling loops. They call this technique a sliptstream process, where it is a side loop with about 5-10% of the main; /archives//html/Amps/2009-12/msg00524.html (8,619 bytes)
99. [Amps] HV connector (score: 1): Author: John Lyles <jtml@losalamos.com>; Date: Tue, 12 Jan 2010 22:52:04 -0700; SHV, MHV all good. I thought I remember MHV being a 10 kV rating, but maybe its another one. The only thing I dislike about these is that they are mostly used on RG58/59 sized cables. If you want to; /archives//html/Amps/2010-01/msg00128.html (6,649 bytes)
100. [Amps] Ferrite sources (score: 1): Author: "John Lyles" <jtml@losalamos.com>; Date: Tue, 26 Jan 2010 17:33:33 -0700; Another very reputable source for 'soft' ferrite toroids is Ferroxcube. They used to be Philips from Eindoven. They make some very good quality LF, MF and HF range ferrites in lower and high mu. They; /archives//html/Amps/2010-01/msg00362.html (7,270 bytes)

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