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

Subject: Re: [Amps] SCR to adjust 240v to 200v
From: Steve Wright <>
Date: Tue, 16 Aug 2016 07:43:10 +1200
List-post: <">>

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 the tubes or disconnecting the filaments, then power-on and monitor the transformer core temperature. Core temp shouldn't be "warming fast and getting hotter and hotter". If you feel you can put a fan on the transformer and it will remain under 50-70 celcius, then I'd be tempted to run it like that.


On 16/08/16 01:45, Jim Durham <> wrote:
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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