[Amps] vacuum relay failure

[Harold B. Mandel]

> I modified my SB-220 about 5 years ago with vacuum relays....

(snip)

Vacuum relays have ratings that are frequency sensitive.

In my Alpha 77Sx clone, the input reed relay was unfortunately
shattered by U.P.S. and so replacement time was at hand.

Exploring other devices and questioning people in the QRO
fraternity, it was discovered  that the Jennings RJ-1 series will
melt down after a while at the 1.5KW level when 10 meter
work is popular. I went with a Jennings RJ-2C for the output
and used the silicon-embedded RJ-1 for the 100 watt input
relay. The amp won't follow 50WPM QSK anymore, but
who cares?

Better to be safe than a tube purchaser.

Hal Mandel 
W4HBM