Topband: Submerging variable caps in oil as substitute for vacuum variables

Pete Smith N4ZR n4zr at
Wed Jan 29 17:42:20 EST 2014

The omega match for my shunt fed tower uses two 300 uF roughly 3000-volt 
variables I bought from Henry radio a few years ago.  I think 
occasionally about running more than 100 watts on 160, but the cost of 
the vacuum variables is a real issue.  February QST has an article on 
using mineral oil immersion to increase the voltage capability of 
variables in a 600M amplifier.  The article does not include any hi-pot 
data, but indicates that the maximum capacitance went up a lot.


73, Pete N4ZR
Check out the Reverse Beacon Network at,
blog at
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.

More information about the Topband mailing list