[R-390] R-390A power switch

[Barry]

I think that may be a fairly common "fix" for the switch.  I know just exercising the plunger for a little while started it working again.  I assume it's just stuck down due to stray lube and/or dust causing the plunger to stay depressed.

Regards,
Barry - N4BUQ

> 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