Hi all,
Colin wrote...
< snip >
> A real advantage of the screen regulator circuit is that it provides
> absolute protection in case the plate voltage is lost for some reason. I
> have built amps without electronic regulation on the screen that had
> excellent imd performance - but there was no protection for loss of plate
> voltage until I used a relay operated by the plate bleeder to give some
> protection. However, if the rf choke had opened, I would have been in
> trouble. There are some fine regulator circuits and boards available and
> they are highly recommended.
I had a nice little 4-65A CW only/ 40m only amplifier many years ago.
I pushed it a bit too hard, and the RF choke opened. A few
milliseconds later, the screen grid (which was regulated, but not
overcurrent protected) lit up like a press-25 flashbulb and died out
like one. I then had a 3-65A. The light show was fun, but with a
metal-ceramic tetrode, it couln't be appreciated. Also, I think I
was spending about $5 for 4-65A's, and 4CX1600B's cost lots more!
Moral: regulate and proctect the screen grid.
73,
George T. Daughters, K6GT
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