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41. Re: [Amps] Transformer in GLA 1000 B : OK for 2xGI 7 ? (score: 1): Author: Steve Thompson <g8gsq@ic24.net>; Date: Tue, 5 Oct 2004 09:31:28 +0100; I think you end up with higher peak and RMS currents in the transformer, leading to a lot extra heat in there. I don't have time right now, but the Duncan Amps PSU designer will predict the numbers.; /archives//html/Amps/2004-10/msg00044.html (7,867 bytes)
42. Re: [Amps] Transformer in GLA 1000 B : OK for 2xGI 7 ? (score: 1): Author: Steve Thompson <g8gsq@ic24.net>; Date: Tue, 5 Oct 2004 18:02:08 +0100; I think that stacks up with the figures I roughed up. My way of judging it is by the rms current - that goes up goes up by around 30%, so the heat goes up by around 70%. Potentially a recipe for a sh; /archives//html/Amps/2004-10/msg00049.html (8,443 bytes)
43. Re: [Amps] Linearity metering (score: 1): Author: Steve Thompson <g8gsq@ic24.net>; Date: Fri, 8 Oct 2004 09:34:46 +0100; Several replies have mention Collins gear having the indicators - optimum tuning indicators and linearity tracers are discussed in 'Single Sideband Principles and Circuits' from 1964. Two of the auth; /archives//html/Amps/2004-10/msg00088.html (7,864 bytes)
44. Re: [Amps] 4CX350 in Dentron Clipperton V ????? (score: 1): Author: "Steve Thompson" <g8gsq@ic24.net>; Date: Sun, 10 Oct 2004 09:04:18 +0100; The control grid of the '350 is much more delicate than in the '250 - it gives better linearity but you have to ensure negligible grid current flows. If it's mostly for FM, and there isn't a sensitiv; /archives//html/Amps/2004-10/msg00125.html (7,200 bytes)
45. Re: [Amps] 4CX350 in Dentron Clipperton V ????? (score: 1): Author: "Steve Thompson" <g8gsq@ic24.net>; Date: Sun, 10 Oct 2004 16:10:04 +0100; I feel sure the ones I've handled were physically identical to 4Cx250s. Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman; /archives//html/Amps/2004-10/msg00132.html (7,596 bytes)
46. Re: [Amps] Looking for a design for a single 4cx250b tube on50Mhz-SixMeters (score: 1): Author: Steve Thompson <g8gsq@ic24.net>; Date: Tue, 12 Oct 2004 17:53:25 +0100; I usually use a series tuned circuit at the input, with a variable capacitor onto the grid to adjust the coupling. That's based on a suggestion I saw that the parallel circuit has the risk of a spuri; /archives//html/Amps/2004-10/msg00179.html (7,742 bytes)
47. Re: [Amps] Blowing off steam (score: 1): Author: Steve Thompson <g8gsq@ic24.net>; Date: Wed, 20 Oct 2004 17:04:51 +0100; Maybe they're not entirely unconnected with the seller? Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps; /archives//html/Amps/2004-10/msg00305.html (7,704 bytes)
48. Re: [Amps] Gettering 4CX800A GU74b (score: 1): Author: Steve Thompson <g8gsq@ic24.net>; Date: Thu, 21 Oct 2004 12:31:57 +0100; http://antennspecialisten.se/~sm5bsz/recondit.htm for example Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo; /archives//html/Amps/2004-10/msg00354.html (8,031 bytes)
49. Re: [Amps] Gettering 4CX800A GU74b (score: 1): Author: Steve Thompson <g8gsq@ic24.net>; Date: Thu, 21 Oct 2004 17:02:53 +0100; The ones I have here don't have one, but the procedure described did improve the hipot results on one that had higher leakage. Steve _______________________________________________ Amps mailing list; /archives//html/Amps/2004-10/msg00362.html (8,919 bytes)
50. [Amps] Gaussmeter (score: 1): Author: "Steve Thompson" <g8gsq@ic24.net>; Date: Sun, 24 Oct 2004 08:56:22 +0100; One with a probe for sale on ebay.co.uk, item 3847257555 Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps; /archives//html/Amps/2004-10/msg00389.html (6,017 bytes)
51. Re: [Amps] re: baking out tubes (score: 1): Author: Steve Thompson <g8gsq@ic24.net>; Date: Tue, 26 Oct 2004 09:15:35 +0100; For what it's worth, my theory is that a well used tube with an oxide cathode has minute amounts of cathode material spread around the inside, and this leads to a leakage level that won't reduce. Ste; /archives//html/Amps/2004-10/msg00419.html (8,226 bytes)
52. Re: [Amps] GU43B amp for 2m ? (score: 1): Author: "Steve Thompson" <g8gsq@ic24.net>; Date: Wed, 27 Oct 2004 07:58:15 +0100; Do tell more, please. Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps; /archives//html/Amps/2004-10/msg00435.html (7,565 bytes)
53. Re: [Amps] re: baking out tubes (score: 1): Author: Steve Thompson <g8gsq@ic24.net>; Date: Wed, 27 Oct 2004 10:10:25 +0100; My thought was that the cathode material is more likely to be very fine films, maybe even closer to atomic level deposits, formed from low level long term evaporation rather than significant particle; /archives//html/Amps/2004-10/msg00437.html (9,054 bytes)
54. Re: [Amps] SB-220 (score: 1): Author: Steve Thompson <g8gsq@ic24.net>; Date: Wed, 3 Nov 2004 18:45:59 +0000; There certainly are parasitics (unwanted vhf oscillation) - especially with tubes with long grid leads - but not every amplifier will have the gain/feedback/load to allow oscillation if suppressors a; /archives//html/Amps/2004-11/msg00039.html (8,311 bytes)
55. Re: [Amps] SB-220 parasitic suppressors (score: 1): Author: "Steve Thompson" <g8gsq@ic24.net>; Date: Thu, 4 Nov 2004 08:15:05 -0000; Feedback C on the data sheet is almost certainly measured at low frequency. The feedback characteristics at V/UHF might be different. By now there's lots of amps out there using the Russian planar tr; /archives//html/Amps/2004-11/msg00063.html (9,012 bytes)
56. Re: [Amps] SB-220 parasitic suppressors (score: 1): Author: Steve Thompson <g8gsq@ic24.net>; Date: Thu, 4 Nov 2004 15:10:48 +0000; The dielectric won't alter, but the impedances probably will. Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/; /archives//html/Amps/2004-11/msg00071.html (9,798 bytes)
57. Re: [Amps] A Meeting Ground (score: 1): Author: Steve Thompson <g8gsq@ic24.net>; Date: Fri, 5 Nov 2004 09:29:04 +0000; Sounds right to me. By 1000 MHz I suspect that the phase angle of the internal feedback might not be exactly -90 degrees - but I also doubt that it's zero. Yes. Consider what happens in a hf amp if t; /archives//html/Amps/2004-11/msg00094.html (9,753 bytes)
58. Re: [Amps] parasitic LC>load? (score: 1): Author: "Steve Thompson" <g8gsq@ic24.net>; Date: Fri, 12 Nov 2004 07:42:49 -0000; I might depend on what's happening to cause the oscillation. A high pass filter from the plate to a load will dampen things if the problem occurs where the plate sees a high impedance but will do lit; /archives//html/Amps/2004-11/msg00163.html (7,912 bytes)
59. Re: [Amps] How to drive 6M 8877 with DownEast 50-28 ... IPA? (score: 1): Author: "Steve Thompson" <g8gsq@ic24.net>; Date: Mon, 29 Nov 2004 22:46:37 -0000; If you want a nice, linear, driver don't waste time with 12V transistors. 28 or 50V makes a world of difference. Something like MRF173 or MRF150 (fets) from RF Parts won't break the bank but will be; /archives//html/Amps/2004-11/msg00459.html (8,537 bytes)
60. Re: [Amps] How to drive 6M 8877 with DownEast 50-28 ... IPA? (score: 1): Author: "Steve Thompson" <g8gsq@ic24.net>; Date: Tue, 30 Nov 2004 22:04:57 -0000; Probably easier to bypass it, or run at 100s mW max output so it's in class A. A modern FET will give you 20+dB gain at 50MHz, so 60W out will mean 0.5W or less input. For comparison, we ran a 2m con; /archives//html/Amps/2004-11/msg00465.html (9,783 bytes)

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