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161. Re: [Amps] plate dissipation and duty factor (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Thu, 12 Mar 2009 18:57:44 +0100; The assumption that duty cycle * peak dissipation = average dissipation holds so long as the pulse lengths or envelope variations are short compared to the thermal time constant of the anode structur; /archives//html/Amps/2009-03/msg00350.html (17,278 bytes)
162. Re: [Amps] Simpson 260 question (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Mon, 3 Aug 2009 21:46:08 +0200; I would strongly advise against measuring non-current limited amplifier plate voltages in the kV region with the standard Simpson 260. The internal and external flash-over distances are not sufficien; /archives//html/Amps/2009-08/msg00062.html (9,966 bytes)
163. Re: [Amps] STP5NB100 - MOSFET from where? (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Tue, 15 Sep 2009 11:00:14 +0200 (CEST); Any 800 - 1000 V 5A N-channel high-voltage MOSFET should work, such as the IRFPF40 or IRFPF50 from International Rectifier. 73/ Karl-Arne SM0AOM Hi to the group. Anyone know where I can get a STP5NB1; /archives//html/Amps/2009-09/msg00191.html (8,100 bytes)
164. Re: [Amps] SRS 360? (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Sun, 1 Nov 2009 09:47:10 +0100; The SRS360 was the DDR manufactured equivalent of the TB3/750 or 5867A. It is a 350 W dissipation medium-mu triode which needs a bias circuit to work properly. An RF amplifier circuit using the TB3/7; /archives//html/Amps/2009-11/msg00000.html (8,676 bytes)
165. Re: [Amps] Right mounting of HV oilfilled C's? (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Mon, 4 Jan 2010 11:24:30 +0100; The "K-film" marking and the capacitance/voltage ratings "rings a bell". Your capacitors may be designed for heart defibrillator use, and those are not suited for filter capacitor service. 73/ Karl-A; /archives//html/Amps/2010-01/msg00014.html (9,247 bytes)
166. Re: [Amps] GU 74 operating parameters (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Wed, 6 Jan 2010 19:56:03 +0100; First, the quoted limits apply to the 4CX800, for the Russian GU74B they are 2000V and 0,5 A respectively. Assuming you will "get away" with the 4CX800 ratings, the plate voltage swing will be limite; /archives//html/Amps/2010-01/msg00030.html (9,170 bytes)
167. Re: [Amps] L section of Pi-L filter (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Wed, 6 Jan 2010 20:16:54 +0100; 1. Toroids have to be quite heavily dimensioned, as they are storing a lot of magnetic energy in a small space. At an L-network Q of 2 they have to store at least 2000 VAr in the toroid magnetic mate; /archives//html/Amps/2010-01/msg00032.html (8,612 bytes)
168. Re: [Amps] Autotune amplifier. How to implement actuator / system for tank switching? (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Sun, 12 Sep 2010 09:42:44 +0200; Take a look at the bandswitch solution used by SM7DLK http://www.qsl.net/sm7dlk/slutsteg.htm at about the middle of the page. It was patterned after a concept used in Marconi 10 kW manually tuned amp; /archives//html/Amps/2010-09/msg00105.html (9,577 bytes)
169. Re: [Amps] Harris AM-7223 AMP (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Thu, 23 Dec 2010 08:31:27 +0100 (CET); Take a look at http://f1frv.free.fr/where a project for operating the RF-353, which is the civilian version of the AM-7223, without the Harris transceiver is described. 73 and Season's Greetings/ Kar; /archives//html/Amps/2010-12/msg00309.html (7,355 bytes)
170. Re: [Amps] Need 35R and 50R 0.25" semi-flexible coax (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Fri, 8 Jul 2011 15:49:02 +0200; The company you are looking after is: http://www.rfmicrowave.it They list both 35 and 50 ohms PTFE semi-rigid coax in small quantities. Not cheap however. 73/ Karl-Arne SM0AOM -- Original Message --; /archives//html/Amps/2011-07/msg00070.html (11,015 bytes)
171. Re: [Amps] Q-value of a plate tank (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Fri, 6 Jan 2012 10:30:41 +0100; The Q-value of a complete pi-tank circuit can be solved by ordinary circuit theory by modeling the circuit as a transducer between the resistive plate impedance of the final tube and a 50 ohm port. A; /archives//html/Amps/2012-01/msg00085.html (9,949 bytes)
172. Re: [Amps] Load testing HV power supplies (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Tue, 25 Sep 2012 07:22:50 +0200 (CEST); When building a 2 x 4-1000A amplifier in the late 70's, I load tested its 3-phase PS using 25 series connected 220 V 200 W light bulbs. With a HV knife switch in series, actuated with a wooden broom; /archives//html/Amps/2012-09/msg00284.html (8,733 bytes)
173. Re: [Amps] Most power ever run on amateur radio :-) (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Wed, 19 Dec 2012 19:29:20 +0100 (CET); I earn part of my living in aeronautical HF since the early 80's. In the mid 80's the 30 kW PEP Telefunken self-tune ransmitters used in Sweden were upgraded with new exciters and a remote control sy; /archives//html/Amps/2012-12/msg00111.html (10,175 bytes)
174. Re: [Amps] Most power ever run on amateur radio :-) (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Wed, 26 Dec 2012 20:44:50 +0100 (CET); Normally, a 10 - 15 kW output amplifier such as the Collins 208U-10 or the Harris RF-126 requires primary fusing using at least 63 A slow-blow to be able to cold-start without risking the fuses (assu; /archives//html/Amps/2012-12/msg00183.html (11,343 bytes)
175. Re: [Amps] Shortwave Returns? [Was: testing the biggest one] (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Sat, 3 Aug 2013 21:09:03 +0200 (CEST); It is all about "price/performance", or cost per prospective listener. The Ministries of Propaganda have decided to use their funds for other purposes than HF broadcast. There's still a lot of Africa; /archives//html/Amps/2013-08/msg00030.html (9,844 bytes)
176. Re: [Amps] 160M PI network Toroidal Coil (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Wed, 9 Oct 2013 10:54:01 +0200 (CEST); The ITU-RR:s have status of international law and treaty, as they form an annex to the Telecommunications Convention. Most countries have them "incorporated by reference" in their national rules and; /archives//html/Amps/2013-10/msg00143.html (9,875 bytes)
177. Re: [Amps] Measuring IMD (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Sat, 2 Nov 2013 09:07:25 +0100 (CET); A quite little known IMD test set is the Racal 9058 Selective Analyser. This is a small self-contained unit consisting of a two-tone generator and a manually tuned direct conversion spectrum analyser; /archives//html/Amps/2013-11/msg00017.html (10,772 bytes)
178. Re: [Amps] Measuring IMD (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Sun, 3 Nov 2013 12:10:48 +0100 (CET); It is sad to read about the death of Warren Bruene. One of the really great in RF engineering have left us. Regarding the use of linearity monitoring with diode detectors at the input and output, I r; /archives//html/Amps/2013-11/msg00026.html (10,494 bytes)
179. Re: [Amps] Measuring IMD (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Sun, 3 Nov 2013 15:31:14 +0100 (CET); The circuit in the ARRL Handbook was intended to establish the static load-line when tuning up, but by adding an oscilloscope it could also be used for indicating dynamic linearity. Similar circuits; /archives//html/Amps/2013-11/msg00028.html (13,151 bytes)
180. Re: [Amps] Best source for Gigavac GH-1 ? (score: 1): Author: Karl-Arne Markström <sm0aom@telia.com>; Date: Sun, 10 Nov 2013 07:09:30 +0100 (CET); Interesting discussion. Usually relays have better reliability than specifications indicate, but QSK operations do put a lot of stress on them. The sequence "TEST W6WRT TEST" contains a total of 6+16; /archives//html/Amps/2013-11/msg00194.html (10,277 bytes)

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