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21. Re: [Amps] GS35b FWB issue (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Mon, 11 Jul 2011 20:52:13 +0100; A problem in the transformer won't show up with a DVM - you'll need to hipot test it. If the transformer is the problem, you won't see it with the bridge connected and floating, only when the -ve end; /archives//html/Amps/2011-07/msg00117.html (6,678 bytes)
22. Re: [Amps] GS35b FWB issue (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Tue, 12 Jul 2011 07:32:10 +0100; Yep, got one of those, blown up some diodes, hence my suggestions. Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/list; /archives//html/Amps/2011-07/msg00122.html (6,536 bytes)
23. Re: [Amps] GS35b FWB issue (score: 1): Author: Steve <g8gsq72@gmail.com>; Date: Wed, 13 Jul 2011 14:23:22 +0100; That was my plan for my problem transformer. If anyone is going to try this, absolutely, definitely, unconditionally MUST have MOVs and fuses on the primary side to protect the mains service from HV; /archives//html/Amps/2011-07/msg00132.html (7,392 bytes)
24. Re: [Amps] GS35b FWB issue (score: 1): Author: Steve <g8gsq72@gmail.com>; Date: Wed, 13 Jul 2011 14:24:28 +0100; Sketch a circuit: transformer secondary, label the ends A and B. Diode from A to the + end of your caps, cathode (arrow and bar) towards the caps. Diode from B to -ve on the caps, cathode to B. -ve; /archives//html/Amps/2011-07/msg00133.html (7,464 bytes)
25. Re: [Amps] MOSFET ratings (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Sun, 17 Jul 2011 23:11:16 +0100; One cross reference for the IXYS transistor you mention is STP4NK80Z. If you look at the ST datasheet, it shows the lower dV/dt as applying to the MOSFET diode and two different circuits for test/mea; /archives//html/Amps/2011-07/msg00211.html (8,161 bytes)
26. Re: [Amps] MOSFET ratings (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Mon, 18 Jul 2011 23:15:23 +0100; OK Manfred. Firstly, I should stress that you must not confuse me with someone who understands all about these MOSFETs :-) Your question spurred my interest. I have been reading from my old (1987) IR; /archives//html/Amps/2011-07/msg00217.html (8,366 bytes)
27. Re: [Amps] TL-922 --> 21st century (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Sun, 14 Aug 2011 16:08:45 +0100; I'll hazard a guess that the idea is to try and create some sort of resonance with the grid wires to reduce feedback at vhf. Steve _______________________________________________ Amps mailing list Am; /archives//html/Amps/2011-08/msg00058.html (7,792 bytes)
28. Re: [Amps] bird meters (score: 1): Author: Steve <g8gsq72@gmail.com>; Date: Thu, 08 Sep 2011 17:35:41 +0100; I don't think you can hurt the slug by winding up the power until it gives 100uA, so DIY testing against another meter is ok. If you prise off the sticky label there's a trimpot accessible through a; /archives//html/Amps/2011-09/msg00014.html (7,561 bytes)
29. [Amps] : MOX resistors (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Sat, 19 Nov 2011 19:09:05 +0000; RS list some - part nos 214-3014, 214-3036 20odd p each in packs of 10. Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman; /archives//html/Amps/2011-11/msg00081.html (6,759 bytes)
30. Re: [Amps] Arcing 8877 (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Fri, 25 Nov 2011 18:35:33 +0000; I had arcing a bit like that fixing a friend's W6PO 2m 8877 amp. It didn't have the big bang take out the fuses side but we could see arcing somewhere around the fins when the power was wound up. It; /archives//html/Amps/2011-11/msg00134.html (8,774 bytes)
31. Re: [Amps] Checking Power FET's (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Sat, 28 Jan 2012 16:47:14 +0000; The most common thing I see in failed FETs is drain to gate leakage or short circuit. Some basic checks: Measure resistance from the gate to drain and then source - both should be very high resistanc; /archives//html/Amps/2012-01/msg00227.html (7,399 bytes)
32. Re: [Amps] HV feed through capacitor (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Sat, 11 Feb 2012 08:59:30 +0000; One of YU1AW's designs gives a size of 80x150mm for the pcb capacitor. Allowing for the dielectric that's in the region of a quarterwave x halfwave. On top of that it's lossy at 432 so if there's any; /archives//html/Amps/2012-02/msg00096.html (7,838 bytes)
33. [Amps] 8874s (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Thu, 16 Feb 2012 08:46:54 +0000; From a UK ham sales site: Rare chance to obtain spare tubes for your amp. Pair of 8874s, unused in original Eimac packing. Offers to g3hrh@btinternet.com I thought folks here might be interested. Oth; /archives//html/Amps/2012-02/msg00192.html (6,554 bytes)
34. Re: [Amps] Customs drilled a hole in my GU74b / 4CX800s (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Thu, 01 Mar 2012 23:15:09 +0000; I think that particle size and density in the air are important factors. As I understand it, serious problems are normally only seen in people who have long term exposure to fine dust. That aside, t; /archives//html/Amps/2012-03/msg00015.html (8,393 bytes)
35. [Amps] Relay suggestions please (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Fri, 09 Mar 2012 08:38:24 +0000; I'm looking at a lower cost alternative to a switching system that currently uses coaxial relays. Frequencies up to 30MHz, powers in the region of 1kW and continuous carrier has to be catered for, bu; /archives//html/Amps/2012-03/msg00067.html (6,434 bytes)
36. Re: [Amps] Relay Suggestions Please (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Fri, 09 Mar 2012 19:25:17 +0000; Many thanks to all for the inputs, both on and off list. I've plenty to be working with. I've used basic power switching relays for antenna switching in the past but this is for a paying customer who; /archives//html/Amps/2012-03/msg00088.html (8,217 bytes)
37. Re: [Amps] 6kW coax? (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Sat, 10 Mar 2012 09:07:38 +0000; If you're using coax for impedance transformation the voltage and/or current levels in some places will be different from the values you expect at 50 ohms and you might need to check the cable is sti; /archives//html/Amps/2012-03/msg00105.html (7,693 bytes)
38. Re: [Amps] 6kW Coax (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Sun, 11 Mar 2012 18:53:37 +0000; I thought 35ohm was max power rating, 75ohm was minimum loss? Hence 75ohms being the standard for CATV. Steve _______________________________________________ Amps mailing list Amps@contesting.com htt; /archives//html/Amps/2012-03/msg00124.html (7,723 bytes)
39. Re: [Amps] 6kW Coax (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Sun, 11 Mar 2012 22:41:47 +0000; Seems my memory is sort of ok. http://www.microwaves101.com/encyclopedia/why50ohms.cfm Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contest; /archives//html/Amps/2012-03/msg00129.html (7,999 bytes)
40. Re: [Amps] Gettering GU-74B's in-place with screen voltage? (score: 1): Author: Steve <g8gsq72@gmail.com>; Date: Mon, 12 Mar 2012 15:32:30 +0000; Might be worth checking if they need gettering. I have some old GU74bs and a NOS 4CX800 which have been sitting on the shelf for several years that I know of. I want to sell them so the first step wa; /archives//html/Amps/2012-03/msg00140.html (8,341 bytes)

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