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141. Re: [Amps] Relais for an antenna crossover switch (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Wed, 27 Jun 2007 13:34:34 +0200; I do not think that you have to worry about the ratings of the 30A relays, but to be sure you are better to make an actual RF current carrying test to check for heating of the relay contacts. The rea; /archives//html/Amps/2007-06/msg00152.html (11,735 bytes)
142. Re: [Amps] suppressors (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Sat, 14 Jul 2007 11:19:13 +0200; Even in smaller transmitters, similar metods had to be used. The very "temperamental" 5 kW PEP Granger 172-2 MF/HF transmitters had several Morganite 100 ohm resistors placed around the anode cooler; /archives//html/Amps/2007-07/msg00219.html (9,882 bytes)
143. Re: [Amps] Gassy Tubes/Technology Museum looking for artifacts (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Thu, 26 Jul 2007 18:21:50 +0200; It is very likely that the 1625 was war-time development to accommodate the 28 V system voltage in larger aircraft. The 1625 is not listed in my RCA TT-3 from 1940, so it must have been introduced la; /archives//html/Amps/2007-07/msg00438.html (10,790 bytes)
144. Re: [Amps] Gassy Tubes/Technology Museum looking for artifacts (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Fri, 27 Jul 2007 13:13:44 +0200 (MEST); It appears that the date quoted on the German web-site for the 1625 was wrong. In the 1942 edition of the "RCA Guide for Transmitting Tubes" that went to press in October/November 1941 the 1625 was i; /archives//html/Amps/2007-07/msg00456.html (11,031 bytes)
145. Re: [Amps] 1625SS (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Tue, 7 Aug 2007 19:54:47 +0200; There is a brief story of the ARC-5/SCR-274 command set evolution, with emphasis on the VHF units, in the document http://www.scr-274-n.info/css.pdf from CQ November 1964. Nothing specific was howeve; /archives//html/Amps/2007-08/msg00022.html (11,492 bytes)
146. Re: [Amps] Off topic question (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Sun, 30 Sep 2007 11:56:15 +0200; The Heathkit HW 12/22/32 single-banders used parallel 6GE5 in their final stages. Also the novice transceivers HW-16 and the 160m transceiver HW-18 used these valve. 73/ Karl-Arne SM0AOM ____________; /archives//html/Amps/2007-09/msg00505.html (7,798 bytes)
147. Re: [Amps] 4CX250 IMD (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Mon, 1 Oct 2007 17:29:41 +0200; The 1961 RCA data sheet for the 4CX250B can be found at: http://frank.pocnet.net/sheets/079/7/7203.pdf 73/ Karl-Arne SM0AOM -- Original Message -- From: "Steve Thompson" <g8gsq@eltac.co.uk> To: <amps; /archives//html/Amps/2007-10/msg00011.html (8,783 bytes)
148. Re: [Amps] 8877 Grid Trip timing (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Tue, 2 Oct 2007 20:04:16 +0200; Actually the "crowbars" in large transmitters are there to save the "tube innards" (grids, cathode) in case of internal arcs which are common occurrence. The sense circuit is connected in the plate r; /archives//html/Amps/2007-10/msg00021.html (9,851 bytes)
149. Re: [Amps] Blocking capacity identity? (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Sun, 4 Nov 2007 18:47:19 +0100; My junkbox also contains such a capacitor. It comes out of the 5 kW Granger Associates 172-2 MF/HF transmitters which were assembled by KW, and was used as the plate blocking capacitor between an Eim; /archives//html/Amps/2007-11/msg00055.html (9,418 bytes)
150. Re: [Amps] 4CX250 MSDS SHEET (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Wed, 12 Dec 2007 13:34:52 +0100 (CET); Years ago, I contacted CPI/Eimac about the possible use of BeO in ordinary power tubes, and got the answer that the external anode/air cooled types did not use BeO in their construction. The only cur; /archives//html/Amps/2007-12/msg00141.html (13,978 bytes)
151. Re: [Amps] 3 1/8 to 7/16 ? (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Wed, 16 Apr 2008 19:05:38 +0200; Years ago, I came across exactly this type of adapter at work. It was manufactured by Spinner GmbH in Germany. Unfortunately, I cannot remember the item number, and the current Spinner on-line catalo; /archives//html/Amps/2008-04/msg00213.html (9,062 bytes)
152. Re: [Amps] Anyone know RF properties of Acrylic?? (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Fri, 23 May 2008 09:12:28 +0200 (CEST); "Reference data for Radio Engineers" lists the dissipation factor for polymethylmethacrylate (the acrylic monomer used in i.a. Plexiglas) as 0.0140 at 1 MHz and 0.0057 at 3 GHz This is about two orde; /archives//html/Amps/2008-05/msg00168.html (8,298 bytes)
153. Re: [Amps] How to test a balun? (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Mon, 26 May 2008 18:44:30 +0200; The "classical" way to check balun performance, at least on lower frequencies, is to connect a balanced resistive load with the correct impedance and the center tap "grounded". Using an RF voltmeter; /archives//html/Amps/2008-05/msg00193.html (9,876 bytes)
154. Re: [Amps] W3NQN band pass filters (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Wed, 11 Jun 2008 17:43:30 +0200; First, I would suggest that you check that the indicated return loss is > 30 dB when the MFJ-269 is terminated with a known good 50 ohm termination. It is difficult to optimise return loss performanc; /archives//html/Amps/2008-06/msg00092.html (10,036 bytes)
155. Re: [Amps] Damage? (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Fri, 25 Jul 2008 22:05:08 +0200; It is very unlikely that modern cars, which are built to very strict EMC specifications, could be interfered with or damaged by amateur power levels, even if parked in the near field of quite large a; /archives//html/Amps/2008-07/msg00267.html (10,881 bytes)
156. [Amps] Ang: Re: Inductor Software? (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Fri, 5 Dec 2008 14:11:10 +0100 (CET); The answer may be closer than you expect. Visit http://www.zerobeat.net/G4FGQ/page3.html and download SOLNOID3. exe This program calculates the inductance of cylindrical air-core coils with reasonabl; /archives//html/Amps/2008-12/msg00103.html (8,289 bytes)
157. Re: [Amps] switchable zener cathode bias (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Wed, 31 Dec 2008 10:33:13 +0100; The easiest way would be to use a single-pole relay or switch contact to parallel the lower-voltage Zener with the higher-voltage one. When in circuit, the lower-voltage Zener will go into conduction; /archives//html/Amps/2008-12/msg00385.html (9,596 bytes)
158. Re: [Amps] measurement of Screen grid current (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Sun, 4 Jan 2009 15:47:40 +0100; There is a slight problem called "LED threshold voltage" in this concept. Most LED:s want a voltage of at least 1 V to produce any light, so it would take at least one ampere of screen current to get; /archives//html/Amps/2009-01/msg00027.html (9,244 bytes)
159. Re: [Amps] Roller Inductor specs (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Sun, 15 Feb 2009 20:22:13 +0100; This is the roller inductor from the BC-375 airborne transmitter. If memory serves me right it is about 18 uH inductance with an approx. 5 ampere RF current rating. 73/ Karl-Arne SM0AOM -- No virus f; /archives//html/Amps/2009-02/msg00481.html (8,364 bytes)
160. Re: [Amps] Roller Inductor specs (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Mon, 16 Feb 2009 09:09:50 +0100 (CET); On a "sunny day" the BC-375 put out about 60 - 100 W CW or AM carrier. The roller inductor was part of a matching network that series-tuned the aircraft wire antennas at the lower HF frequencies. Rat; /archives//html/Amps/2009-02/msg00490.html (10,186 bytes)

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