[CQ-Contest] Voltage Requirement for Variable Capacitor for Shunt Feeding Tower

i4jmy at iol.it i4jmy at iol.it
Tue Jan 9 10:47:05 EST 2001


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 > I'm trying to shunt feed my tower on 160 Meters. The ON4UN Low Band DXing
 > book gives an idea of what value I need in PFs for the capacitance, but
 > nothing about voltage. I'm planning on running legal limit and using two air
 > type variable capacitors. What voltage do I need for these capacitors?
 >
 > 73, Ken, K6LA, Ken Six Los Angeles
 >
 > K6LA at GTEMAIL.NET

Unfortunately You didn't explain if you are going to use a Gamma or an
Omega match, how tall is the tower and where you want to tap.
In case of gamma, the voltage of capacitor depends by various factors,
mostly by where the tap for shunt feeding is connected to the tower and
also by the height of tower and the amount of top loading.
Roughly, as much the tap point is raised up in the tower the voltage
increases, as much as the tap is lowered the voltage decreases but the
required capacity increases.
A capacitor like those used for plate tuning in tube amplifiers could
be adequate, in terms of voltage isolation in most shunt feed
applications.

73,
Mauri I4JMY
    


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