Quote:
Originally Posted by astral highway
Does that sound fast enough? It all needs to be over in less than 5mS, to protect the rectifier chain in the power supply. They're good for a huge overload for around 10mS, but perhaps not repetitively. I know 5mS is actually quite a long time, but it's important for me to think this through.
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We used to test ours by hanging a piece of thin wire (the diameter of 5A fuse wire but not actual fuse wire) to the 26kV d.c. rail, through a vac switch, to deck, switching on the transmitter and firing the vac switch remotely. If all was well, the wire would be intact. That's how quick it was. I would say it would carry 10A before the crowbar kicked in and took the supply off. Sometimes the wire discoloured a little.
A 1us trigger pulse was initiated via one of two C/Ts (or the modulator valve grid deck C/Ts) to fire the ignitron, via a thyristor, followed by a 150ms sustain pulse to dump energy and at the same time, throw in a vac switch across the d.c. via a 320 Ohm discharge resistor.
Quote:
Originally Posted by astral highway
Does it mean that corona inception voltage is lower at high frequencies than at lower frequencies?
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Correct. As the frequency rises, the corona onset voltage falls. Not only that, but at RF, the corona onset voltage and flashover damage point are very close indeed, as opposed to power line networks where there is a distinct gap between corona and flashover. I take it you've no sharp edges?