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In a message dated 18/07/2004 06:43:33 GMT Standard Time, we0h@genesiswireless.us writes:

Hi David,
What would you recommend for a supply voltage with 500v FET's in your Quarter Kilowatt linear amp design?

Mike
WE0H
WD2XGI

Hi Mike.

I converted my version of the 250W linear to class D by fitting a 4013 chip and the TC4426 FET driver etc from the other class D circuit. I used the IRFP450.

With no other changes it gave 600 W out from a 48V supply and had some spare capacity for those moments when you really want the QSO (about 700W CW on 56V)

I would have thought 60V was the max safe limit. An oscillosope on the drains will be enough to shock you into not going beyond that (it was for me)

Also used the same amp for a 500km QSO on 73kHz from Scotland. It clicked and fizzed like crazy on that band, but held up OK

David G0MRF