[R-390] R-390A power switch

[Jim Haynes]

Just recently I got around to working on the permanently-turned-on
power switch on a receiver.  I lucked out with this one - when I took
the Microswitch off the main switch, it started opening and closing
again.

Anyway, before putting the front panel back on, I put a spark suppressor
consisting of 0.1uF in series with 100 ohms across the switch contacts.
One wonders why something like this was not built into the receiver
originally, since the power switch is such a known problem area.
Maybe the military never complained because they kept their receivers
turned on all the time.

It remains to be seen if this will effectively eliminate the switch
problem.  It would probably be just as effective to put the suppressor
across the power transformer primary, which might be easier to get to.

Jim W6JVE

jhhaynes at earthlink dot net