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Re: [Amps] SCR to adjust 240v to 200v

To: "'Jim Durham'" <>
Subject: Re: [Amps] SCR to adjust 240v to 200v
From: "Peter Voelpel" <>
Date: Mon, 15 Aug 2016 18:40:50 +0200
List-post: <">>
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.


-----Original Message-----
From: Amps [] On Behalf Of Jim Durham
Sent: Freitag, 12. August 2016 19:07
Subject: [Amps] SCR to adjust 240v to 200v

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 

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 all is fine, except I'd like 
to ditch the variac and was wondering about if anyone on here had any 
wise words about using an SCR instead to back the AC voltage off.

My experience with big SCRs (TV studio lighting) was that they tend to  
put out a lot of RF hash.  I also wonder about how the choke and filter 
cap in the power supply would like non-sinusoidal AC waveform?

Anyone have any experience with this?

Thanks and 73,

Jim, W2XO

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