Check the math -- 1% is 20 watts on a 2 KW amp -- a real doorknob cap would
be fine. However, as Mr. Measures pointed out, current at 30 MHz can be
considerable, and I^2R effects will push losses up.
I think that's why RF Parts and Copper Electronics charge so much for
replacement plate blocking caps. That get re-replaced every year....
Since I have a decent sized dummy load and some expendable finals, I might
try some experiments with low-pF blocking caps. I would be suitably
surprised (and delighted) to find that an ARC-5 antenna vacuum cap would
work in place of a $50. doorknob cap at 30 MHz and a kilowatt.
Jim N6OTQ
"Tom Rauch" <w8ji@akorn.net> said --
>If you lost even 1% of the power output in the blocking cap, it would
>explode, melt, sag, or turn to smoke.
>
>One of the biggest myths around is that blocking caps noticeably
>affect efficiency.
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