[Milsurplus] Aging Variable Caps. was: SKN SNAFU

[David Stinson]

----- Original Message ----- 
From: "Laura and Jim" <mcenfalz at humboldt1.com>
Subject: [Milsurplus] SKN SNAFU


> CW Frequency "warbles" occasionally when transmitting. I'll set it at a 
> certain freq, tune it up, then when underway, it'll drop 100-130 kc 
> intermittently then pop back up. When it drops in freq, I have to re-tune 
> it, then (of course) it pops back up to the starting frequency....

I'm starting to see this in older rigs, especially in Command Sets.
There are some mechanically press-fit junctions in the variable
capacitors.  Look on the end where the wires connect in an "ARC-5"
transmitter and you'll see a "strip," press fit on the end of the stator.
This connection gets Hi-Z intermittantly. I fixed a couple some years ago
by using a 12-volt supply and soft wire to "spot-weld" across the problem.
Did the same for a BC-454 cap that had the problem on a couple of spots
on the stator.  Take the end of a wooden dowel or something and tap
on the tuning cap while key-down.

Secondarily:  A lot of solder joints are showing their age.
Tap on joints while key-down and look for the intermit.

73 Dave S.