Ken Warren wrote:
I tried a zero crossing controller in a 750 volt power supply prior to
running it on the 3KV plate supply and my experience was that the
laminations in the transformer made so much noise that it was not usable.
The audio from the modulator caused the laminations to act as a speaker
and it was loud enough to cause feedback. The transformer did have well
sealed laminations. I would like to know if others have tried this also
with the same result
If you are referring to a solid-state relay which switches at the zero crossing
point (I'm not sure of the terminology), they are VERY sensitive to RF. I had
problems with the relay partly opening in the presence of RF. In my case I was
using it to control a linear PS which was powering a solid-state 750-watt HF
amplifier, and the result was that the PS drew more current in an attempt to
maintain regulation, which blew primary fuses. When I noticed that this did not
happen when transmitting into a dummy load, I realized that RF was the issue.
I had to bypass and filter both the primary and control circuits to solve this
problem. Maybe your noise was caused by the controller dropping out at an audio
rate in response to the RF?
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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