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1. [Amps] Step-start and 3-500Z filament life (score: 1): Author: "Bill W5WVO" <w5wvo@cybermesa.net>; Date: Sat, 5 Dec 2009 20:41:35 -0700; I understand why turning a tube's filaments off and on repeatedly shortens the tube's useful life. However, I'm not clear about the effects of doing this when a step-start circuit is included (as in; /archives//html/Amps/2009-12/msg00143.html (6,995 bytes)
2. Re: [Amps] Step-start and 3-500Z filament life (score: 1): Author: Ron Youvan <ka4inm@tampabay.rr.com>; Date: Sun, 06 Dec 2009 04:25:48 +0000; I think of "step-start" as applying to the plate supply, to minimize the initial capacitor charging current and preventing a hV over shoot, and inrush limiting to be applied to initial filament heat; /archives//html/Amps/2009-12/msg00144.html (8,035 bytes)
3. Re: [Amps] Step-start and 3-500Z filament life (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Sat, 5 Dec 2009 23:37:14 -0500; It is my understanding that the SB220 doesn't need step start for the filaments as the transformer has enough internal resistance/inductance to limit the inrush to a safe value for the tubes. 73 Gary; /archives//html/Amps/2009-12/msg00145.html (9,092 bytes)
4. Re: [Amps] Step-start and 3-500Z filament life (score: 1): Author: vk3pa@vk3pa.com; Date: Sat, 05 Dec 2009 22:38:27 -0600; _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps; /archives//html/Amps/2009-12/msg00146.html (8,335 bytes)
5. Re: [Amps] Step-start and 3-500Z filament life (score: 1): Author: "Jim W7RY" <w7ry@arrl.net>; Date: Sat, 5 Dec 2009 21:11:00 -0800; Negative. There are 2 transformers in a SB-220. 1 filament and 1 for HV. The step start mod (from harbaugh) is wired in series with both transformer primaries. So step start helps both HV and filamen; /archives//html/Amps/2009-12/msg00149.html (9,559 bytes)
6. Re: [Amps] Step-start and 3-500Z filament life (score: 1): Author: "Carl" <km1h@jeremy.mv.com>; Date: Sun, 6 Dec 2009 09:30:18 -0500; You might ask Merit Arnold, W6NQ, of RF Parts that question as he is a regular reader of this forum. The SB-220 filament transformer is self limiting by design and allows a rather gentle start up. Iv; /archives//html/Amps/2009-12/msg00156.html (9,380 bytes)

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