The author points out (correctly) the tempco issues with oil dielectric.
Still I am intrigued by the thought of a remote tuning capacitor via hydraulic
tubing :-). The capacitor plates could be as simple as two concentric cylinder
conductors with appropriate spacers. I betcha crud collecting on the top of the
oil would set voltage limit.
Tim N3QE
----- Original Message -----
From: Pete Smith N4ZR [mailto:n4zr@contesting.com]
Sent: Wednesday, January 29, 2014 05:42 PM
To: topband@contesting.com <topband@contesting.com>
Subject: Topband: Submerging variable caps in oil as substitute for vacuum
variables
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.
Opinions?
--
73, Pete N4ZR
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