On 6/3/2011 8:25 AM, John G3UUT wrote:
> Another caution, this time about constant voltage transformers. I had
> one of these and tried to use it to stabilise the mains to a signal
> generator to improve drift. It sort of worked but the main problem with
> it was that it distorted the mains waveform quite badly, sufficiently so
> that a normal moving coil meter read very inaccurately. I'm not sure if
> all constant voltage transformers have this problem but some certainly
> do so if you want to set the filament to a particular voltage make sure
> you use a true RMS reading meter.
All the ones I have experience with work that way. I think I may still
have one that is 750VA or maybe 1KVA. Wave form is really ratty which is
how they control the RMS voltage. We used them on the input to the
double walled calibration screen room where you'd think a pure sine wave
would be needed.
73
Roger (K8RI)
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