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361. Re: [Amps] Some thoughts on a transistorized legallimit amplifier... (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Sun, 14 Oct 2007 23:18:31 +0100; Sorry, I should have said the AM/PM I was thinking of was in the varactor effect in the semiconductor junctions when the output stage drain/collector voltage was modulated. I suspect that it would ge; /archives//html/Amps/2007-10/msg00179.html (8,274 bytes)
362. Re: [Amps] Testing 8874s (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Fri, 02 Nov 2007 07:23:48 +0000; Is there any benefit in a hipot test between those two steps? Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/; /archives//html/Amps/2007-11/msg00015.html (7,365 bytes)
363. Re: [Amps] How to measure output power of a 800W vhf amp (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Sat, 03 Nov 2007 13:28:07 +0000; No, 30dB is just fine - it will give you 0.5-0.8W output which is 5-6V rf. I tried a simple detector at 144MHz with 51R resistor, 1N4148 and 10nF capacitor (very short leads on all of them). Feeding; /archives//html/Amps/2007-11/msg00039.html (7,816 bytes)
364. Re: [Amps] Caddock power resistors (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Tue, 13 Nov 2007 21:06:54 +0000; Farnell/Newark list them at £6.25/$13 each. As an alternative Anaren 250W flange mount stripline resistors and terminations were around £10/$20 ea. when I last bought them some months ago; /archives//html/Amps/2007-11/msg00195.html (9,585 bytes)
365. Re: [Amps] more dangers in our shack (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Sat, 17 Nov 2007 22:09:32 +0000; A lot? The only tube I know of which has BeO in its structure is used in the UK Clansman 353 tank radio. This has BeO between the anode and a conduction cooling mounting flange. CCS1 and 8873 use a B; /archives//html/Amps/2007-11/msg00236.html (7,780 bytes)
366. Re: [Amps] Misconceptions about hazmat in ham radio equip (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Sun, 18 Nov 2007 08:51:39 +0000; I'm intrigued by 'had to' - do you know why? It is also in beryllium-copper metal used for EMI gasket material As I understand it: Be metal in BeCu is very safe. Raw Be is nasty, but no-one will enco; /archives//html/Amps/2007-11/msg00243.html (7,382 bytes)
367. Re: [Amps] more dangers in our shack (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Sun, 18 Nov 2007 08:57:04 +0000; Interesting. In the 4CX250s I've opened up, I don't recall seeing any ceramic in the grid support structures - but these would have been 60/70s date codes. As you say, maybe the original design was d; /archives//html/Amps/2007-11/msg00244.html (7,591 bytes)
368. Re: [Amps] BeO in tubes/tinwhiskers (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Sun, 18 Nov 2007 23:47:07 +0000; Yes - but the average life of iPod/cell phones is something like 6 months before they are tossed in the trash, so it's not a problem and it achieves the aim of restricting the lead going into landfil; /archives//html/Amps/2007-11/msg00265.html (8,865 bytes)
369. Re: [Amps] BeO in tubes/tinwhiskers (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Mon, 19 Nov 2007 08:56:21 +0000; I was musing on this overnight - tin 'whiskers' with lead free solder is an issue in where there's very fine line spacing on component legs/pcbs. I think there's a different problem we'll see, and pr; /archives//html/Amps/2007-11/msg00271.html (8,600 bytes)
370. Re: [Amps] Winding large inductors (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Tue, 20 Nov 2007 22:11:49 +0000; I've used sand very successfully to avoid pipe kinking when bending - although not for inductor winding. With larger coils and heavy wire I anchor the far end and wind the free end onto a former, wal; /archives//html/Amps/2007-11/msg00290.html (7,807 bytes)
371. Re: [Amps] Nicotine from last owner :-( (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Sat, 08 Dec 2007 09:23:20 +0000; Being really pedantic, what's troubling you is mostly tar, not nicotine. That will point you at effective solvents if you want to wash it away. The alternative is to drive off the volatile content w; /archives//html/Amps/2007-12/msg00061.html (7,412 bytes)
372. Re: [Amps] input/output transformer switching (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Thu, 13 Dec 2007 07:48:40 +0000; I doubt it would work. The impedances at the transistor side of the transformer are very low (few ohms) so any inductance from the switching will totally mess up the higher frequency operation. I su; /archives//html/Amps/2007-12/msg00149.html (8,224 bytes)
373. Re: [Amps] input/output transformer switching (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Fri, 14 Dec 2007 18:14:41 +0000; I think that Tempo did a similar sort of thing with the 6N2, and there was a lovely amp using a pair of 3CX800s on the amps projects web site (the address escapes me) using the same idea. I've no id; /archives//html/Amps/2007-12/msg00163.html (8,279 bytes)
374. Re: [Amps] input/output transformer switching (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Sun, 16 Dec 2007 08:48:33 +0000; I've just noticed the prices Henry are selling for on ebay. It's not as big a hole as it used to be. I think I paid close on $500 for the first one I bought years ago. One thing with fets that's som; /archives//html/Amps/2007-12/msg00169.html (7,892 bytes)
375. [Amps] FET bias (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Wed, 26 Dec 2007 08:24:57 +0000; A very common failure mode when FETs blow is to go drain-gate short. If bias feeds for multiple devices are tied together the higher voltage fed into the network from the blown device can apply exce; /archives//html/Amps/2007-12/msg00253.html (7,108 bytes)
376. Re: [Amps] High voltage (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Wed, 26 Dec 2007 08:33:44 +0000; I'd argue it's only butchery if something can't be undone - like modifying metalwork, for example. If I kludge in an ugly string of diodes in a way that means they can be removed without leaving a t; /archives//html/Amps/2007-12/msg00254.html (7,173 bytes)
377. [Amps] 220MHz amp (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Mon, 31 Dec 2007 14:37:04 +0000; I recall a while ago someone was asking for a copy of the W6PO 220MHz amp (based on the 144MHz version). I thought I had a copy but couldn't find it at the time. I bumped into it today. If anyone is; /archives//html/Amps/2007-12/msg00284.html (6,619 bytes)
378. Re: [Amps] My HV supply design. (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Thu, 03 Jan 2008 07:49:32 +0000; In the case of an arc, you end up with a lot of volts across R13 which could have consequences for the tube, insulation and decoupling components depending on how your amp is configured. A low value; /archives//html/Amps/2008-01/msg00024.html (7,371 bytes)
379. Re: [Amps] HV Supplies and Diodes (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Fri, 04 Jan 2008 09:13:18 +0000; It's worth pointing out that the peak current in the transformer is the same as the peak current in the diodes. The heating effect of the current flowing in short peaks (in a cap input supply) is 2.5; /archives//html/Amps/2008-01/msg00056.html (8,543 bytes)
380. Re: [Amps] 3 kV switch mode supply (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Thu, 10 Jan 2008 20:58:59 +0000; For starters, try searching for designs by W5JGV, W3REF and S57UUU. Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/li; /archives//html/Amps/2008-01/msg00092.html (6,513 bytes)

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