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References: [ +from:Peter.Chadwick@zarlink.com: 335 ]

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281. Re: [Amps] power vacuum tube hi-pot and "conditioning" (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Mon, 3 May 2004 17:41:32 +0100; Traian, is the effect you're seeing the same as the 'vac ion pump' that some big tubes have? As I understand it, the ionisation attracts the gas ions to the electrode and keeps the vacuum up. I first; /archives//html/Amps/2004-05/msg00035.html (7,875 bytes)
282. Re: [Amps] List (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Fri, 7 May 2004 08:40:35 +0100; I'm going to be there, God and American Airlines willing (American are the dodgy part!), staying at the Crowne Plaza Hotel (33 East 5th St) from Wednesday through Saturday nights. Flying out 1850 on; /archives//html/Amps/2004-05/msg00070.html (6,671 bytes)
283. Re: [Amps] DVM recomendation (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Fri, 7 May 2004 08:42:28 +0100; If you are looking to do measurements round an amplifier when there's RF around, get an analogue meter! I haven't found a digital voltmeter yet that behaves with a lot of RF around. 73 Peter G3RZP __; /archives//html/Amps/2004-05/msg00071.html (7,288 bytes)
284. Re: [Amps] Kenwood 830S Filters (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Mon, 24 May 2004 09:02:15 +0100; Try http://www.qth.com/inrad/ for crystal filters. George, W2VJN, (as far as I know, he hasn't changed his call) is very knowledgeable about these matters. 73 Peter G3RZP ____________________________; /archives//html/Amps/2004-05/msg00212.html (6,983 bytes)
285. Re: [Amps] feeding the input (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Mon, 31 May 2004 11:44:05 +0100; Carl was asking about feedback resistors in cathode/filament circuits. The answer it that it seems to vary. The Mullard data sheet for the QY3-125 (which is basically a 6151/ 4-125, as opposed to 4D2; /archives//html/Amps/2004-05/msg00275.html (7,584 bytes)
286. Re: [Amps] feeding the input (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Tue, 1 Jun 2004 07:35:25 +0100; Carl, Mtybe I didn't say it well enough. Which side of the filament the RF return (which is the input in g-g) goes to seems sometimes to be specified, and sometimes not. In the case of the 572B's, if; /archives//html/Amps/2004-06/msg00001.html (7,121 bytes)
287. Re: [Amps] Fwd: High Voltage inverter? (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Thu, 8 Jul 2004 19:56:31 +0200; can Certainly doesn't HAVE to. Anyone using the ISM band has to accept any interference they get. If the microwave oven next door wipes out your WLAN, tough. 73 Peter G3RZP __________________________; /archives//html/Amps/2004-07/msg00044.html (7,594 bytes)
288. Re: [Amps] HV fuse (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Fri, 23 Jul 2004 09:19:31 +0100; Asbestos powder has also been used in the past, but not these days. The filling is called 'anti rupture powder': the idea is to keep the fuse wire intact although molten until it reaches a sufficient; /archives//html/Amps/2004-07/msg00154.html (8,914 bytes)
289. Re: [Amps] RE: 4CX250B Screen Supplies (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Tue, 27 Jul 2004 09:17:25 +0100; Some professional tests use a very narrow spacing between tones - as low as 30Hz - to simulate the syllabic nature of voice, and to exercise the power supply regulation. Another approach, which, if I; /archives//html/Amps/2004-07/msg00209.html (11,112 bytes)
290. Re: [Amps] RE: 4CX250B Screen Supplies (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Thu, 29 Jul 2004 09:40:44 +0100; The HP141T will just about do it to 30dB down or so on the 10Hz RBW position. Of course, it needs to be well warmed up, and takes a long time on narrow sweep with the persistence up. No good for a sw; /archives//html/Amps/2004-07/msg00224.html (10,132 bytes)
291. Re: [Amps] Resonant choke filter (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Mon, 2 Aug 2004 10:03:35 +0100; Is actual resonance what you want? The argument I've seen runs as follows; In a choke input supply, there's a critical minimum value of inductance for regulation. At low currents, this is very high,; /archives//html/Amps/2004-08/msg00008.html (8,129 bytes)
292. Re: [Amps] Resonant choke filter (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Wed, 4 Aug 2004 09:00:10 +0100; Because the critical choke inductance in a choke input filter varies inversely with the current, the swinging choke can have less air gap i.e. less reluctance than a non swinging choke. This means th; /archives//html/Amps/2004-08/msg00030.html (11,199 bytes)
293. Re: [Amps] Line Isolators for RF feedback (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Tue, 10 Aug 2004 09:23:21 +0200; I found that the measured common mode impedance ona supposedly identical arrangement to the W2AU balun gave rather less common mode suppression. However, the losses about 5%, or about 0.22dB. That st; /archives//html/Amps/2004-08/msg00081.html (9,993 bytes)
294. Re: [Amps] Line Isolators for RF feedback (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Tue, 10 Aug 2004 15:47:31 +0200; Ferrites used in non-transmission line transformers can get quite hot at high power levels e.g.40kW. I've seen 50 - 600 ohm 40kW xfmrs: they used 2 legs, each with 24 rings stacked. Each ring was 6 i; /archives//html/Amps/2004-08/msg00086.html (8,770 bytes)
295. Re: [Amps] Line Isolators for RF feedback (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Wed, 11 Aug 2004 17:10:35 +0200; tuning, The cores can get hot before they saturate, just by virtue of the energy used moving the domains around the B-H curve. I suspect that because of their permittivity, a high voltage on them can; /archives//html/Amps/2004-08/msg00100.html (9,216 bytes)
296. Re: [Amps] Large Zeners Follow-up. (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Thu, 12 Aug 2004 09:10:35 +0200; Worth remembering that the forward drop of a silicon diode decreases by 2mV/degree C. Zeners go one way below about 5.6 volts, and the other way above 6, and I can never remember which it is - I thin; /archives//html/Amps/2004-08/msg00107.html (7,571 bytes)
297. Re: [Amps] 20kw Dummy load? (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Fri, 13 Aug 2004 09:26:07 +0200; Robin was asking about water cooling resistors. The old metal film ones from Electrosil in the UK which were 50 watts in air were used professionally at 30kW. If I remember correctly (and it was 40 y; /archives//html/Amps/2004-08/msg00120.html (7,758 bytes)
298. Re: [Amps] 3-500ZG brands (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Fri, 13 Aug 2004 09:54:19 +0200; There's a lot of things described as 'silver solder'. Basically, there are three types - 'soft', 'medium' and 'hard'. Soft solders with some silver in them are relatively low temperature solders, and; /archives//html/Amps/2004-08/msg00121.html (9,394 bytes)
299. Re: [Amps] Suggestions to quiet a blower (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Mon, 16 Aug 2004 09:21:44 +0200; *guess* is related to the ball bearing Ball bearings are noisy. A straight plain bearing would be a lot quieter. but if the fan is supposed to be quiet, it may well be plain bearings anyway. If not,; /archives//html/Amps/2004-08/msg00150.html (7,779 bytes)
300. Re: [Amps] GBR and radiation exposure (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Fri, 20 Aug 2004 11:44:28 +0200; My father in law spent many years working at the big stations at Rugby (new - 30kW HF tx's) and old - the GBR site with a few 100kW tx's, at Leafield with lots of QRO HF, and on the tropo scatter lin; /archives//html/Amps/2004-08/msg00221.html (7,227 bytes)

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