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181. [AMPS] More on the SB220 (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Sat, 20 Mar 1999 00:25:04 +0000; I've heard of both gas inclusions and surface imperfections that might be the same as Eimac's 'barnacles'. Whatever the cause, improvements such as pure, gas-free metals and better processing can cer; /archives//html/Amps/1999-03/msg00504.html (9,670 bytes)
182. [AMPS] More on the SB220 (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Sat, 20 Mar 1999 12:03:51 +0000; It's been years since I worked on an SB-220, so I didn't have the circuit handy, but have now downloaded it from Rich's web site (thanks!). R3 is not involved in the normal anode-cathode HV current p; /archives//html/Amps/1999-03/msg00506.html (10,605 bytes)
183. [AMPS] Big Tetrodes at UHF (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Mon, 22 Mar 1999 00:29:19 +0000; As I understand it, gas-induced arcs wouldn't the tube to be biased on, because the arc doesn't need electrons in order to get going - it only needs HV and a source of material to ionize. The arc the; /archives//html/Amps/1999-03/msg00531.html (8,388 bytes)
184. [AMPS] Info needed: Soild Statte Relays (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Sun, 21 Mar 1999 23:48:15 +0000; To: <amps@contesting.com> Are they also OK for power OFF, as part of a fast protection setup? In addition to their normal current carrying rating, do SSRs have a separate (hopefully much higher) over; /archives//html/Amps/1999-03/msg00532.html (8,350 bytes)
185. [AMPS] More on the SB220 (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Sun, 21 Mar 1999 23:40:56 +0000; A normal silicon rectifier diode has no detectable effect on meter calibration at 500mV (I checked with a DMM) but it starts to conduct significantly at around 600mV. That's why it's nice to design t; /archives//html/Amps/1999-03/msg00533.html (10,001 bytes)
186. [AMPS] High watt Zeners ! (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Mon, 22 Mar 1999 21:23:58 +0000; A TL431 "adjustable zener" with a cheap PNP darlington transistor such as a TIP147 will give continuously adjustable bias voltage that is rockstable up to at least 2A (which a zener or a transistor+z; /archives//html/Amps/1999-03/msg00566.html (8,186 bytes)
187. [AMPS] PA loading and tube life (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Mon, 29 Mar 1999 14:44:39 +0100; Another significant issue is that 30 or more years ago, in the period up to the time when the Eimac application note was written, VHF amps were notorious for their hit-and-miss output coupling arrang; /archives//html/Amps/1999-03/msg00671.html (8,257 bytes)
188. [AMPS] morse code on ships (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Mon, 1 Feb 1999 13:53:19 +0000; It is also something that people want to use, simply because they enjoy using it. In *amateur* radio - done for the love of it - we don't have to use the "best" mode or the "most efficient". Simply e; /archives//html/Amps/1999-02/msg00021.html (8,227 bytes)
189. [AMPS] Metering a GG amp (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Mon, 1 Feb 1999 20:14:22 +0000; Shunts are better when everything is working normally, because they produce the minimum voltage drop, -BUT- in the event of current surge (due to an arc or whatever) it's more difficult to protect sh; /archives//html/Amps/1999-02/msg00039.html (8,939 bytes)
190. [AMPS] FW: Mail failure (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Mon, 1 Feb 1999 21:44:14 +0000; ...followed by 136 lines of quotes from previous messages. Did somebody mention unwanted messages? 73 from Ian G3SEK Editor, 'The VHF/UHF DX Book' 'In Practice' columnist for RadCom (RSGB) http://www; /archives//html/Amps/1999-02/msg00051.html (7,786 bytes)
191. [AMPS] Input Tuned Circuits with Powdered Iron Toroids (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Wed, 10 Feb 1999 07:45:04 +0000; It seems that the input network is actually providing a reflection for harmonic energy, not a matched termination. So... just speculating... in a multi-band amplifier, would it make sense to wire the; /archives//html/Amps/1999-02/msg00295.html (9,403 bytes)
192. [AMPS] coil form plastics (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Sat, 13 Feb 1999 09:31:07 +0000; Probably by not using it in situations of high RF stress (voltage gradient) or high temperature. I've managed to melt Delrin by putting it in a particularly stupid place in a 144MHz PA running only 2; /archives//html/Amps/1999-02/msg00357.html (11,174 bytes)
193. [AMPS] coil form plastics (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Sun, 14 Feb 1999 11:28:09 +0000; ... I think Dick's examples illustrate the point very well - it's much more about *where* you use it than the material you choose. Unfortunately it's not much more than an intuition based on my physi; /archives//html/Amps/1999-02/msg00372.html (10,620 bytes)
194. [AMPS] coil form plastics (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Mon, 15 Feb 1999 00:05:05 +0000; Yes, it is clear that external heating could not cause the internal bubbling. But that tells you nothing about whether they will work well enough in a particular situation. As Dick has pointed out, t; /archives//html/Amps/1999-02/msg00387.html (9,761 bytes)
195. [AMPS] coil form plastics (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Mon, 15 Feb 1999 00:18:09 +0000; Fair enough - anything involving high RF potentials (and probably high temperatures too) is a risky application that would need careful testing before committing to production. It's more difficult fo; /archives//html/Amps/1999-02/msg00388.html (9,936 bytes)
196. [AMPS] Screen stabilization in 30S-1? (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Sat, 27 Feb 1999 14:16:13 +0000; Someone e-mailed to ask how to stabilize the screen voltage in the Collins 30S-1. The 30S-1 uses a 4CX1000 with a DC-grounded screen, and it derives its total anode-cathode voltage from a positive an; /archives//html/Amps/1999-02/msg00688.html (7,994 bytes)
197. [AMPS] Smoking/Eating in the Multi Op Room!? (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Fri, 1 Jan 1999 07:40:26 +0000; Only Dan could say that, and still live to see a New Year! Have a good one, everybody. 73 from Ian G3SEK Editor, 'The VHF/UHF DX Book' 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.dem; /archives//html/Amps/1999-01/msg00008.html (6,776 bytes)
198. [AMPS] Plate load charts (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Tue, 5 Jan 1999 15:25:13 +0000; There are various methods for calculating the Pi and Pi-L network values, some more approximate than others. As has been pointed out already, approximate methods are actually OK for this application.; /archives//html/Amps/1999-01/msg00073.html (12,396 bytes)
199. [AMPS] Plate load charts (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Tue, 5 Jan 1999 18:54:30 +0000; Well, there's always the old VHF/UHF trick of pressurizing the whole output compartment. Cold air circulates all around the tank circuit and the lower part of the tube, and then flows out through the; /archives//html/Amps/1999-01/msg00075.html (10,111 bytes)
200. [AMPS] HV Connectors (score: 1): Author: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK); Date: Sat, 16 Jan 1999 11:11:13 +0000; IMO a coaxial connection *is* necessary, for safety reasons. The "nightmare scenario" that you're trying to avoid is where the two chassis are at different potentials because they're interconnected o; /archives//html/Amps/1999-01/msg00214.html (9,957 bytes)

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