Re: Capacitor and coil form questions (fwd)
---------- Forwarded message ----------
Date: Tue, 13 Jan 1998 20:23:00 -0800 (PST)
From: "Edward V. Phillips" <ed-at-alumni.caltech.edu>
Subject: Re: Capacitor and coil form questions (fwd)
Take an 8"x8"x12" glass fish tank, cut metals plates so that they are
suspended on the ledges at the top of the tank, and have a connecting
bolt running down each side connecting alternate plates. Fill the tank
with transformer oil. I have calculated that 85 plates, 2.5mm appart
should give he the desired capacitance.
I think that this design has several advantages, the di-electric is
self healing, and it is easy to adjust capacitance and voltage. For me
these outway the difficulty of moving and setting up the capacitor"
That's mighty close spacing!!! You would need very flat
plates, rigidly supported. In my opinion that would be nearly
impossible to achieve in practice.
As for the self healing - not so simple. I have a couple of
variable capacitors immersed in oil here. When breakdown occurs the
oil is carbonized, and think a complete emptying of oil, flushing and
washing plates in solvent, and refilling would be needed.
There was an article in QST sometime around 1921 describing
a 375 meter (800 kHz) spark transmitter using jus such a capacitor.
The builder/designer seemed to think it worked fine. (Those guyhs
guys knew their stuff back then!)