[Boatanchors] Variable Capacitors needed

Robert Nickels ranickel at comcast.net
Tue Feb 17 12:17:08 EST 2009


I'm afraid I'm fighting a losing battle trying to reclaim two variable 
capacitors from the HT-20 transmitter I've been restoring.  They were 
badly corroded, and despite chemical and mechanical cleaning which 
provided a temporary fix, I still am getting arcing between the plates 
with B+ applied.  There must be enough irregularity on the surfaces to 
allow corona discharge, and there's no practical way to restore the the 
original surface smoothness and cad plating.

So, I'm hoping someone might have a parts unit, a deep junkbox, or 
suggestions on a replacement source.  I need two pieces, 12-250 pf, in 
what was generally called the "midget" style, made by Hammarlund, Bud, 
Millen and others.   Mine have the "midline" or "straight-line" plate 
design but as long as the capacitance is the same I think the 
semi-circular plates would work as well.   Need to be the double-bearing 
type  with 3/8" bushing for panel-mounting,  and ideally, rated at 1000 
volts.   Representative part numbers include:

Hammarlund MC-250-M
National STH-250
Bud 1859
Millen 19200

The best option I've found so far is the MFJ 282-2006, but I'd rather 
find vintage caps with a higher breakdown rating if possible.

Thanks and 73,
 Bob W9RAN




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