In the October 1987 QST there was a construction article for line side
proportional control regulator for a high voltage power supply. Its
purpose is to prevent the HV from soaring under idling conditions when
the tube was not drawing current. The circuit uses a comparator to
sample the HV and turn a triac in the primary of the transformer either
off or on depending up the relationship of the sample to a reference
voltage.
I don't think I have ever seen this circuit implemented in any designs
or any discussion about it. I am building a new amp and was thinking
about using it. Is it a good idea or are the draw backs to it?
David
KW4DH
Jim Thomson wrote:
> Yep. Emtron have been doing it for many years and it is superb.
>
> Alek,
> VK6APK
>
>
> ### ramping up over how long a period of time, 5 x secs, 10 x secs
> 1x sec, or what I suspect is from a zero cross point, up to the top
> of the cycle.. [IE: 4.17 msecs] ????
>
> ## will the triac handle the huge pulses every 8.3 msecs??
>
> ## My problem with the SSR's is... they need a BIG heatsink
> They should also be supplemented with a breaker or fuses.
> There is too much leakage current through them imo. If you
> are working on an amp that has them,un-plug from the
> 240v line 1st.
>
> ## IF you decide on using SSR's... get one that has a
> zero cross voltage turn on.... and a zero cross CURRENT
> turn OFF.
>
> Later... Jim VE7RF
>
>
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>
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