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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: Chris Wilson <>
Reply-to: Chris Wilson <>
Date: Sat, 13 Aug 2016 11:31:03 +0100
List-post: <">>

Hello Jim,

On Friday, August 12, 2016,  you wrote:

> 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.

> 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

Buck transformer, for sure, SCR's are more complex a solution, and may
give noise or other issues.

Best regards,

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