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1. [Amps] SCR to adjust 240v to 200v (score: 1): Author: Jim Durham <jimdur@gmail.com>; Date: Fri, 12 Aug 2016 13:07:17 -0400; Hello all, This is my first posting, so Howdy.. I have a Henry 2k-2 (modified to take 3-500Zs). After I bought it, some years back, I fired it up and tube filaments were very bright and HV was high.; /archives//html/Amps/2016-08/msg00007.html (7,182 bytes)
2. Re: [Amps] SCR to adjust 240v to 200v (score: 1): Author: Ron Youvan <ka4inm@gmail.com>; Date: Fri, 12 Aug 2016 15:00:00 -0400; /* snip */ Talked to Henry. They asked me the plate transformer number, which they looked up and said "Oh, that's the 200v European transformer". So, I put a hefty variac on the 240v AC incoming and; /archives//html/Amps/2016-08/msg00008.html (7,885 bytes)
3. Re: [Amps] SCR to adjust 240v to 200v (score: 1): Author: Michael Clarson <wv2zow@gmail.com>; Date: Fri, 12 Aug 2016 15:41:33 -0400; Jim: Motorola did something like you describe in their "MOTRAC" series base stations (beige cabinets) in the 1960s and 70s. These were 250-350 watt output stations using a pair of 8560s as finals. Th; /archives//html/Amps/2016-08/msg00009.html (9,752 bytes)
4. Re: [Amps] SCR to adjust 240v to 200v (score: 1): Author: Jim Durham <jimdur@gmail.com>; Date: Fri, 12 Aug 2016 17:11:05 -0400; My real reason for asking was not whether the SCR would work to vary the voltage, that's done all the time, but it does put spikes in the AC waveform. I'm sure Henry never anticipated such and how th; /archives//html/Amps/2016-08/msg00011.html (10,467 bytes)
5. Re: [Amps] SCR to adjust 240v to 200v (score: 1): Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>; Date: Fri, 12 Aug 2016 22:13:09 -0400; I've used a lot of high power SCRs in industry and built controllers using them. As Roy said, they will likely prove to be very difficult because of the tremendous hash they create. An SCR is turned; /archives//html/Amps/2016-08/msg00012.html (10,388 bytes)
6. Re: [Amps] SCR to adjust 240v to 200v (score: 1): Author: Jim Durham <jimdur@gmail.com>; Date: Sat, 13 Aug 2016 11:11:33 -0400; Thank you, Boye (OZ7C) and the others that replied. I think I did not explain my project clearly. First of all, yes, I know about buck transformers. I am using a Variac, which does the same thing and; /archives//html/Amps/2016-08/msg00013.html (9,887 bytes)
7. Re: [Amps] SCR to adjust 240v to 200v (score: 1): Author: Chris Wilson <chris@chriswilson.tv>; Date: Sat, 13 Aug 2016 11:31:03 +0100; Hello Jim, Buck transformer, for sure, SCR's are more complex a solution, and may give noise or other issues. -- Best regards, Chris mailto:chris@chriswilson.tv ______________________________________; /archives//html/Amps/2016-08/msg00014.html (9,320 bytes)
8. [Amps] SCR to adjust 240v to 200v (score: 1): Author: "Jim Thomson" <jim.thom@telus.net>; Date: Sat, 13 Aug 2016 09:35:59 -0700; /* snip */ I would measure the incoming line Voltage RMS then I would locate a used 240 Volt to (normal Voltage - 200) Volt transformer and buck the: 240 - 200 = 40 Volts at enough Amps with it. SCRs; /archives//html/Amps/2016-08/msg00015.html (9,620 bytes)
9. Re: [Amps] SCR to adjust 240v to 200v (score: 1): Author: Jim Brown <jim@audiosystemsgroup.com>; Date: Sun, 14 Aug 2016 13:11:45 -0700; Not quite. What is needed is a boost-buck transformer to go in series/parallel with the primary of the big transformer in the PSU. Primary of the boost/buck goes across the 240V line, secondary goes; /archives//html/Amps/2016-08/msg00016.html (9,331 bytes)
10. [Amps] SCR to adjust 240v to 200v (score: 1): Author: "Jim Thomson" <jim.thom@telus.net>; Date: Mon, 15 Aug 2016 07:42:24 -0700; Thank you, Boye (OZ7C) and the others that replied. I think I did not explain my project clearly. First of all, yes, I know about buck transformers. I am using a Variac, which does the same thing and; /archives//html/Amps/2016-08/msg00018.html (9,434 bytes)
11. Re: [Amps] SCR to adjust 240v to 200v (score: 1): Author: Jim Brown <jim@audiosystemsgroup.com>; Date: Mon, 15 Aug 2016 08:34:33 -0700; I'm sure that Motorola carefully designed so that there was no RFI at VHF/UHF. But this sort of circuitry is FAR more likely to generate trash at MF and HF. Bottom line -- it's not necessarily a slam; /archives//html/Amps/2016-08/msg00019.html (8,794 bytes)
12. Re: [Amps] SCR to adjust 240v to 200v (score: 1): Author: Michael Clarson <wv2zow@gmail.com>; Date: Mon, 15 Aug 2016 12:12:53 -0400; Yes, Jim. The Motorolas were all VHF/UHF. They did make them to work as low as 25 MHz, which was just barely HF. I never liked fixing those supplies. Lightning was always taking out some of the semic; /archives//html/Amps/2016-08/msg00020.html (10,097 bytes)
13. Re: [Amps] SCR to adjust 240v to 200v (score: 1): Author: Jim Brown <jim@audiosystemsgroup.com>; Date: Mon, 15 Aug 2016 09:30:25 -0700; No surprise. About 40 years ago, I had a job maintaining and troubleshooting a wide range of installed systems -- audio, video, security, etc. One was a simple intercom in an apartment complex that u; /archives//html/Amps/2016-08/msg00021.html (10,125 bytes)
14. Re: [Amps] SCR to adjust 240v to 200v (score: 1): Author: Jim Brown <jim@audiosystemsgroup.com>; Date: Mon, 15 Aug 2016 09:21:48 -0700; What it does that is the same is that it adjusts the primary voltage. But it is VERY different from a boost/buck transformer, because it must be rated for the full VA of the load. A boost/buck transf; /archives//html/Amps/2016-08/msg00022.html (10,052 bytes)
15. Re: [Amps] SCR to adjust 240v to 200v (score: 1): Author: "Peter Voelpel" <dj7ww@t-online.de>; Date: Mon, 15 Aug 2016 18:40:50 +0200; There is and was no European country with 200V mains. You don´t need a variac, just use a 40V transformer and put it in the primary of the hv transformer with the proper phasing to subtract 40V. 73 P; /archives//html/Amps/2016-08/msg00024.html (9,976 bytes)
16. Re: [Amps] SCR to adjust 240v to 200v (score: 1): Author: mike via Amps <amps@contesting.com>; Date: Mon, 15 Aug 2016 14:26:12 -0400; I can sell you a filament transformer from a SB-220 and that would solve the filament problem. --Original Message-- From: Peter Voelpel <dj7ww@t-online.de> To: 'Jim Durham' <jimdur@gmail.com> Cc: amp; /archives//html/Amps/2016-08/msg00026.html (10,425 bytes)
17. Re: [Amps] SCR to adjust 240v to 200v (score: 1): Author: Steve Wright <stevewrightnz@gmail.com>; Date: Tue, 16 Aug 2016 07:43:10 +1200; If you can drop the filament voltage by winding an opposing turn somewhere, or maybe a large resistor - the rest of it can probably be ignored. Test the 200V transformer running at 230V, by removing; /archives//html/Amps/2016-08/msg00028.html (10,038 bytes)
18. Re: [Amps] SCR to adjust 240v to 200v (score: 1): Author: Roger D Johnson <n1rj@roadrunner.com>; Date: Mon, 15 Aug 2016 15:25:27 -0400; Probably Japanese. Their standard mains voltage is 100 VAC. 73, Roger There is and was no European country with 200V mains. _______________________________________________ Amps mailing list Amps@cont; /archives//html/Amps/2016-08/msg00029.html (8,593 bytes)
19. [Amps] SCR to adjust 240v to 200v (score: 1): Author: "Jim Thomson" <jim.thom@telus.net>; Date: Tue, 16 Aug 2016 09:15:17 -0700; There is and was no European country with 200V mains. You don?t need a variac, just use a 40V transformer and put it in the primary of the hv transformer with the proper phasing to subtract 40V. 73 P; /archives//html/Amps/2016-08/msg00035.html (8,742 bytes)
20. [Amps] SCR to adjust 240v to 200v (score: 1): Author: "Jim Thomson" <jim.thom@telus.net>; Date: Tue, 16 Aug 2016 09:20:36 -0700; I can sell you a filament transformer from a SB-220 and that would solve the filament problem. fil xfmr ! It truly is a stupid idea, since then u can never operate the amp with just one tube installe; /archives//html/Amps/2016-08/msg00036.html (8,873 bytes)

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