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201. Re: [Amps] making sinks black (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Sun, 23 Jul 2006 09:36:46 +0200 (CEST); Somewhen back in the early 1970's (showing my age!) there was an article in one of the professional UK electronics magazines (long defunct). The people had done work on heat transfer from heat sinks.; /archives//html/Amps/2006-07/msg00917.html (9,636 bytes)
202. Re: [Amps] making aluminum heat sinks black (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Sun, 23 Jul 2006 09:57:46 +0200 (CEST); cheek... take note of the radiant heat you feel from the bottom side vs. the dark teflon side. Dramatic to say the least. Almost none is felt from the bottom, the dark side radiates a great deal of h; /archives//html/Amps/2006-07/msg00918.html (8,691 bytes)
203. Re: [Amps] 3cx3000A7 driver (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Sun, 23 Jul 2006 12:50:49 +0200 (CEST); also the aggregated noise properties of the amplifiers and level control loops.< I wasn't strictly considering them, but it's very true, they're another set of limitations. There was a paper at last; /archives//html/Amps/2006-07/msg00921.html (9,246 bytes)
204. Re: [Amps] "Tubes 201" - How Vacuum Tubes Really Work (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Sun, 23 Jul 2006 13:04:53 +0200 (CEST); He does tell you not to leave grids open, though. When you have grid current, you have grid dissipation. Which is why tubes designed for Class C had carbon coatings or whatever to reduce emission. Se; /archives//html/Amps/2006-07/msg00923.html (8,594 bytes)
205. Re: [Amps] 3-500Z convertion (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Sun, 23 Jul 2006 13:14:31 +0200 (CEST); The 4X500A is an external anode tube, so the cooling won't be right, it needs a different socket, and it's a tetrode. You'd need to do soem careful calculation to determine if the grid and screen dis; /archives//html/Amps/2006-07/msg00925.html (7,868 bytes)
206. Re: [Amps] 3-500Z convertion (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Sun, 23 Jul 2006 16:58:55 +0200 (CEST); The big problem will be arranging the cooling. My RCA book says the maximum seal temperature is 150 deg C, and they don't look from the drawing easy to arrange cooling around it. I have little doubt; /archives//html/Amps/2006-07/msg00935.html (7,665 bytes)
207. Re: [Amps] "Tubes 201" - How Vacuum Tubes Really Work (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Sun, 23 Jul 2006 17:09:59 +0200 (CEST); Definitely not, Mr. Chadwick. < Definitely not what? That I'm the only one who doesn't buy the idea of grid fuses as bad idea? That there are published articles that have been around for years about; /archives//html/Amps/2006-07/msg00936.html (9,051 bytes)
208. Re: [Amps] grid fuses (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Sun, 23 Jul 2006 17:21:19 +0200 (CEST); Carl, My feeling is that 572Bs are a bit close to the edge anyway once you get to 28MHz.. They have very long grid leads, especially when compared with a 3-500Z. Even a copper strap to ground from th; /archives//html/Amps/2006-07/msg00937.html (8,368 bytes)
209. Re: [Amps] 572B grid (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Mon, 24 Jul 2006 06:35:20 +0200 (CEST); http://w2dtc.com/1964-waters-tech-bulletin.jpg< I need a large tub of salt for this one. Like the clock that strikes 13 and makes you wary of anything else it says, the claim that running the KWM2 P; /archives//html/Amps/2006-07/msg00986.html (7,275 bytes)
210. Re: [Amps]The maximum amount of 811As and 572Bs in parallel (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Mon, 24 Jul 2006 07:21:49 +0200 (CEST); Adding tubes increases capacitance in the same proportion as it reduces optimum load impedance, and tank operating Q isn't a critical parameter at all as long as it exceeds a certain amount.< Not onl; /archives//html/Amps/2006-07/msg00994.html (7,920 bytes)
211. Re: [Amps] "Tubes 201" - How Vacuum Tubes Really Work (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Mon, 24 Jul 2006 07:40:09 +0200 (CEST); with a good vacuum.< It's sad that G6JP is no longer alive. He spent his entire working life doing tube manufacture and applications at the M-O valve company, and he said that flashovers weren't unco; /archives//html/Amps/2006-07/msg00996.html (9,786 bytes)
212. Re: [Amps] 3cx3000A7 driver (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Mon, 24 Jul 2006 07:44:52 +0200 (CEST); If I remember correctly, the Anglian used two TV type turret tuners for band selection, ganged together mechanically, with a ganged switch for the PA. It was about the time that turret tuners were go; /archives//html/Amps/2006-07/msg00998.html (8,503 bytes)
213. Re: [Amps] 3-500Z convertion (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Mon, 24 Jul 2006 07:56:27 +0200 (CEST); Rich a Chinese tube is similar. < Are you saying that you can replace the original 2 tubes with just one? And get the same output, but only have half the plate dissipation? 73 Peter G3RZP ___________; /archives//html/Amps/2006-07/msg00999.html (8,259 bytes)
214. Re: [Amps]The maximum amount of 811As and 572Bs in parallel (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Mon, 24 Jul 2006 07:58:39 +0200 (CEST); Rich, amplifiers.< Were they actually in parallel, or were they a distributed amplifier? 73 Peter G3RZP _______________________________________________ Amps mailing list Amps@contesting.com http://li; /archives//html/Amps/2006-07/msg01001.html (7,461 bytes)
215. Re: [Amps] 3-500Z convertion (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Tue, 25 Jul 2006 10:59:46 +0200 (CEST); Major confusion here........I thought he needed to replace both of them. From what Karl Arne said, it sounds a bit as if the 4X500 is 4-250/4-400 with a different base and an external anode. That mak; /archives//html/Amps/2006-07/msg01066.html (8,988 bytes)
216. Re: [Amps]The maximum amount of 811As and 572Bs in parallel (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Tue, 25 Jul 2006 11:22:34 +0200 (CEST); Distributed amplifiers are a totally different ballgame to putting tubes in parallel. They're not efficient - one, done in the early 1960's used 2 amplifiers in push-pull, each using eight 4CX250Bs.; /archives//html/Amps/2006-07/msg01068.html (8,412 bytes)
217. Re: [Amps] "Tubes 201" - How Vacuum Tubes Really Work (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Tue, 25 Jul 2006 11:41:55 +0200 (CEST); Two things make grids emit. One is heat. You try to minimise that by flashing of gold etc, although if you boil that off, it's not there, so you're left with the basic material. Unfortunately, in oxi; /archives//html/Amps/2006-07/msg01069.html (9,697 bytes)
218. Re: [Amps] Looking for info: SRF7053 device (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Tue, 25 Jul 2006 12:22:19 +0200 (CEST); in replacements.< Generally, it seems that in the semiconductor world, analogue second sources very rarely are. Oh, sometimes, but even such mundane devcies as a 741 op amp can vary enough in some pa; /archives//html/Amps/2006-07/msg01073.html (8,323 bytes)
219. Re: [Amps] "Tubes 201" - How Vacuum Tubes Really Work (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Tue, 25 Jul 2006 12:43:18 +0200 (CEST); between one or two sections.< Might be instructive to see good (or otherwise!) the strong signal performance is, too. The first solid state converters, even with FETS, were pretty awful in comparison; /archives//html/Amps/2006-07/msg01074.html (9,193 bytes)
220. Re: [Amps] setting the grid adrift (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Wed, 26 Jul 2006 10:23:31 +0200 (CEST); stories would be different than what has been reported here.< I have a suspicion that results will depend on the particular tube. 73 Peter G3RZP _______________________________________________ Amps m; /archives//html/Amps/2006-07/msg01145.html (7,078 bytes)

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