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201. Re: [Amps] MTBF - was Ameritron Amps (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Mon, 31 Jul 2006 11:20:59 -0400; ..and you can't blindly grab a number like "2000 hours" NOT apply it to the component manufacturer's formula for using that very number to determine life, and think you know the actual MTBF. 2000 ho; /archives//html/Amps/2006-07/msg01437.html (8,273 bytes)
202. Re: [Amps] Ameritron Amps (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Mon, 31 Jul 2006 11:27:04 -0400; The factory should have been smart enough to tell your buddy to check the resistors first Mike. That's their fault. The best capacitor in the world would have failed the same way with bad resistors.; /archives//html/Amps/2006-07/msg01438.html (9,386 bytes)
203. [Amps] Glass failures Chinese tubes (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Mon, 31 Jul 2006 13:52:38 -0400; Peter, Don't let yourself get trolled OM. The glass failures in the Chinese tubes were soft spots that sucked in about midway down the side walls. It wasn't anywhere near where the electric field wo; /archives//html/Amps/2006-07/msg01444.html (9,176 bytes)
204. Re: [Amps] Low Pass Filter capacitor ratings for 1.5kw level (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Tue, 1 Aug 2006 13:32:16 -0400; Mike, The biggest worry is generally current rating, not voltage rating. A secondary worry is impedance of leads if you intend to reject very high frequency harmonics. The caps must of course have t; /archives//html/Amps/2006-08/msg00009.html (8,208 bytes)
205. Re: [Amps] Ameritron Amps (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Tue, 1 Aug 2006 13:40:57 -0400; If that is true I wonder why tubes in push-pull amplifiers don't blow up, why the output of a PP amp isn't zero, why a push-pull self excited oscillator is easily possible to build and why it works; /archives//html/Amps/2006-08/msg00010.html (9,373 bytes)
206. Re: [Amps] Low Pass Filter capacitor ratings for 1.5kw level (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 2 Aug 2006 04:49:37 -0400; In the 50's and 60's or earlier that might have been good advice. Not any longer though. Anyone who has ever looked at a modern Ham radio (i.e. a real amateur transceiver like a Y K I) on a spectrum; /archives//html/Amps/2006-08/msg00034.html (9,871 bytes)
207. Re: [Amps] Limits of a Power transformer (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 2 Aug 2006 04:56:03 -0400; I think you'll find a 160 ohm ESR transformer has horrible regulation. The hypersil in the AL12 series for example has about 10 ohms of secondary resistance. The AL-811 around 20 ohms ESR. With 160; /archives//html/Amps/2006-08/msg00035.html (7,695 bytes)
208. Re: [Amps] AL811, AL811H or AL572 mods to 6m (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 2 Aug 2006 05:06:09 -0400; The 811A and 572 have two problems that can affect this. First, they have high feedthrough capacitance. This requires neutralization even at upper HF if you use two or more 572 and four or more 811A; /archives//html/Amps/2006-08/msg00036.html (8,254 bytes)
209. Re: [Amps] Limits of a Power transformer (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 2 Aug 2006 06:53:25 -0400; I should have been clearer. Of course the ERS is a combination of losses that are the effective resistance. We can be sure the actual ESR is always higher than the dc secondary resistance. 73 Tom __; /archives//html/Amps/2006-08/msg00042.html (7,917 bytes)
210. Re: [Amps] AL811, AL811H or AL572 mods to 6m (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 2 Aug 2006 13:30:44 -0400; The only problem doing that is stability. It generally works OK to do that with a very stable tube like a 3CX1500A7 or 3CX800A7, but tubes with long grid leads can get a bit squirrelly. 73 Tom _____; /archives//html/Amps/2006-08/msg00051.html (8,577 bytes)
211. Re: [Amps] grid resonance (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 2 Aug 2006 21:26:49 -0400; It's not too complicated Carl. You have to know what frequency is the parallel resonance. Series resonances, which mean the grid is most effective, will show up on a GDO. You are also measuring outs; /archives//html/Amps/2006-08/msg00060.html (9,277 bytes)
212. Re: [Amps] grid resonance (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 2 Aug 2006 22:13:01 -0400; Say what? I thought GDOs only detected parallel resonances. I was taught that to check a series resonance one had to connect the two open ends together, thus making a parallel resonance.>> Think a li; /archives//html/Amps/2006-08/msg00062.html (7,035 bytes)
213. Re: [Amps] grid resonance (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Thu, 3 Aug 2006 06:04:42 -0400; Constant voltage swept frequency source, and you detect voltage at the anode. 73 Tom _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com; /archives//html/Amps/2006-08/msg00079.html (7,958 bytes)
214. Re: [Amps] Limits of a Power transformer (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Thu, 3 Aug 2006 06:13:29 -0400; I think you are using the approximation where a full wave rectifier center tapped transformer is used in a bridge. You would How do you get 155mA at no load? With load The figure you always use is w; /archives//html/Amps/2006-08/msg00080.html (8,692 bytes)
215. Re: [Amps] grid resonance (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Thu, 3 Aug 2006 07:08:44 -0400; You missed the point of my question. You stated that a GDO can be used to find a series resonance. My understanding is that's not You missed my point also. We shouldn't apply a snip of fact to a comp; /archives//html/Amps/2006-08/msg00081.html (9,772 bytes)
216. Re: [Amps] Grid Vs cathode drive (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Thu, 3 Aug 2006 07:32:29 -0400; Do you mean the S1? If you look at actual tests of IM all these "clean" grid driven 4CX800 tetrodes are nowhere as good as a cathode driven 3CX800 or similar. When you look at the regulation and pro; /archives//html/Amps/2006-08/msg00082.html (7,803 bytes)
217. Re: [Amps] grid resonance (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Thu, 3 Aug 2006 17:31:32 -0400; -- REPLY SEPARATOR -- In an earlier post you said "Series resonances, which mean the grid is most effective, will show up on a GDO.">> That's correct, because it is not a lunmped two compoennt netwo; /archives//html/Amps/2006-08/msg00109.html (9,096 bytes)
218. Re: [Amps] Grid Vs cathode drive (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Thu, 3 Aug 2006 17:56:44 -0400; CB screwed it up, not the FCC. Hams not only gve up 11 meters, the CB amplifier builders and users wound up forcing the power gain limitations, the 50 watt minimum drive, automatic (RF) keying ban,; /archives//html/Amps/2006-08/msg00110.html (9,730 bytes)
219. Re: [Amps] grid resonance (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Thu, 3 Aug 2006 19:29:32 -0400; I've got a problem with a measurement. I wanted to compare a GDO reading with a network analyzer S12 reading, but I'm having some difficulties getting a reading on my old Heath meter. I can't get any; /archives//html/Amps/2006-08/msg00113.html (8,589 bytes)
220. Re: [Amps] Grid Vs cathode drive (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Fri, 4 Aug 2006 05:59:23 -0400; That's absolutely true. There is little doubt all radios would remain about 100 watts. The bulk of radios always were in that range, and as many people or more didn't use amps as who do use amps. Th; /archives//html/Amps/2006-08/msg00136.html (8,388 bytes)

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