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281. Re: [Amps] HN connectors (score: 1): Author: Steve Thompson <g8gsq@qsl.net>; Date: Mon, 29 Sep 2003 14:47:04 +0100; A personal opinion. Don't use any connector where: (a) it's possible to touch the centre pin of either half (b) the shield is not guaranteed to make first and break last. Hard wire or buy SHV. Anythi; /archives//html/Amps/2003-09/msg00203.html (7,405 bytes)
282. Re: [Amps] Power meter calibration (score: 1): Author: Steve Thompson <g8gsq@qsl.net>; Date: Mon, 6 Oct 2003 14:48:07 +0100; There isn't a simple single formula, it depends on the characteristics of the diode, and the rf voltage and dc current. In some designs, the diodes are used with rf voltages where the diode drop is s; /archives//html/Amps/2003-10/msg00049.html (8,224 bytes)
283. Re: [Amps] Soft 8877??? (score: 1): Author: Steve Thompson <g8gsq@qsl.net>; Date: Tue, 7 Oct 2003 11:19:36 +0100; Could it be that the loading is much too heavy, so the plate sees too low a resistance? Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contes; /archives//html/Amps/2003-10/msg00057.html (7,959 bytes)
284. Re: [Amps] Conditioning Spare Tubes After Storage (score: 1): Author: "Steve Thompson" <g8gsq@qsl.net>; Date: Sun, 12 Oct 2003 09:11:11 +0100; It's difficult to see how it could cause any harm. I've used the guidelines in SM5BSZ's site. I still go that route if a tube is leaky on a hipot test. Steve _________________________________________; /archives//html/Amps/2003-10/msg00089.html (7,897 bytes)
285. Re: [Amps] Transistor Bias (score: 1): Author: "Steve Thompson" <g8gsq@qsl.net>; Date: Sat, 18 Oct 2003 12:23:16 +0100; It's a common, but poor, substitute for doing it properly. Have a read of http://www.ifwtech.co.uk/g3sek/tr-bias/tr-bias1.htm and/or look up some Motorola hf amp app. notes which use a circuit with a; /archives//html/Amps/2003-10/msg00159.html (8,172 bytes)
286. Re: [Amps] Tuned Input and the MFJ-259B (score: 1): Author: "Steve Thompson" <g8gsq@qsl.net>; Date: Fri, 24 Oct 2003 07:59:47 +0100; Zero, but if it's a grounded grid amp, the tuning needs to be done at power, not small signal. Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists; /archives//html/Amps/2003-10/msg00225.html (7,343 bytes)
287. Re: [Amps] About single 4CX250b output power (score: 1): Author: Steve Thompson <g8gsq@qsl.net>; Date: Mon, 27 Oct 2003 10:36:25 +0000; The STC datasheet gives typical 2 tone operating figures of -30dBc 3rd order and -50dBc 5th order at 325W pep, 2kV anode supply and 100mA quiescent.. I reckon you do well to get that much output in p; /archives//html/Amps/2003-10/msg00245.html (7,518 bytes)
288. Re: [Amps] About single 4CX250b output power (score: 1): Author: Steve Thompson <g8gsq@qsl.net>; Date: Mon, 27 Oct 2003 14:06:25 +0000; I guess that some unbypassed cathode resistance might also work to improve linearity. I have a vague memory of seeing an article about cathode driven '250s, but can't recall when/where. Steve _______; /archives//html/Amps/2003-10/msg00251.html (8,002 bytes)
289. Re: [Amps] matched MOSFETs (score: 1): Author: Steve Thompson <g8gsq@qsl.net>; Date: Thu, 30 Oct 2003 14:18:47 +0000; Provide separate bias setting pots and there's no need to match Vgs. +/- 10% on gm was a normal selection when I was on that side of things. If the devices come from the same batch code, use separate; /archives//html/Amps/2003-10/msg00300.html (7,274 bytes)
290. Re: [Amps] H2O cooled tubes (score: 1): Author: "Steve Thompson" <g8gsq@qsl.net>; Date: Fri, 31 Oct 2003 07:55:46 -0000; I think I remember a design in VHF Communications that used oil. A tiny bit of conductivity might not be a bad thing. One place I worked (just before my time unfortunately) prototyped a really compac; /archives//html/Amps/2003-10/msg00305.html (7,778 bytes)
291. Re: [Amps] 4CX800 Linear (score: 1): Author: Steve Thompson <g8gsq@qsl.net>; Date: Wed, 5 Nov 2003 12:08:53 +0000; Problems with a variable - possible unwanted resonances, and still a poor current path to earth through bearings/bushes etc. Better is to replace the disk with an 'L' shaped flapper, screwed solidly; /archives//html/Amps/2003-11/msg00053.html (8,747 bytes)
292. Re: [Amps] plate transformers (score: 1): Author: "Steve Thompson" <g8gsq@qsl.net>; Date: Fri, 7 Nov 2003 08:04:34 -0000; Then measure the winding resistances and use the Duncan Amps PSU program to get a good prediction of what they will do in practice. Steve _______________________________________________ Amps mailing; /archives//html/Amps/2003-11/msg00085.html (7,393 bytes)
293. Re: [Amps] slow down circuits for 240v blower (score: 1): Author: Steve Thompson <g8gsq@qsl.net>; Date: Tue, 18 Nov 2003 14:37:57 +0000; Have you tried a series capacitor? Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps; /archives//html/Amps/2003-11/msg00251.html (7,961 bytes)
294. Re: [Amps] AC or DC better for indirectly heated cathodes? (score: 1): Author: Steve Thompson <g8gsq@qsl.net>; Date: Wed, 19 Nov 2003 15:36:18 +0000; Repays itself in no time at all if you're ever going to operate portable. Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailm; /archives//html/Amps/2003-11/msg00273.html (8,010 bytes)
295. Re: [Amps] AL-1200 Questions (score: 1): Author: Steve Thompson <g8gsq@qsl.net>; Date: Tue, 25 Nov 2003 10:35:50 +0000; My knowledge of atomic physics is limited, but it strikes me as much more likely that some of the gold balls have cathode material on them. Steve _______________________________________________ Amps; /archives//html/Amps/2003-11/msg00360.html (8,356 bytes)
296. Re: [Amps] AL-1200 Questions (score: 1): Author: Steve Thompson <g8gsq@qsl.net>; Date: Wed, 26 Nov 2003 17:42:58 +0000; I'd be surprised if it was there in large enough lumps to see. Do you see the effect once the balls are out of the tube? Steve _______________________________________________ Amps mailing list Amps@c; /archives//html/Amps/2003-11/msg00373.html (9,113 bytes)
297. Re: [Amps] AL-1200 Questions (score: 1): Author: Steve Thompson <g8gsq@qsl.net>; Date: Thu, 27 Nov 2003 11:17:33 +0000; I think they don't need to be. If something delivers enough energy to spray melted gold from the grid everywhere, I reckon that it's highly likely that some cathode material gets sprayed around as we; /archives//html/Amps/2003-11/msg00379.html (9,348 bytes)
298. Re: [Amps] Homebrew solid state amps? (score: 1): Author: Steve Thompson <g8gsq@qsl.net>; Date: Fri, 12 Dec 2003 10:19:51 +0000; Helge Granberg did some designs using 4 x MRF150s for 600W out, and the MRF157 datasheet includes a design for a 1kW amp. Another layer or two of combining should get you there. If your amp doesn't n; /archives//html/Amps/2003-12/msg00197.html (7,444 bytes)
299. Re: [Amps] MLA-2500 question (score: 1): Author: Steve Thompson <g8gsq@qsl.net>; Date: Fri, 12 Dec 2003 10:29:31 +0000; From memory, it's used to peak the directivity of the coupler. Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo; /archives//html/Amps/2003-12/msg00198.html (7,210 bytes)
300. Re: [Amps] Input Matching for 8877 on 2m (score: 1): Author: Steve Thompson <g8gsq@qsl.net>; Date: Fri, 12 Dec 2003 10:28:16 +0000; Wind an airspaced coil of similar size, and manually squeeze/stretch it (and the second L) until you get a match that tunes nicely with the variable C. Rewind for more/less L as you find necessary. S; /archives//html/Amps/2003-12/msg00199.html (7,667 bytes)

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