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Re: Topband: Fw: 25G insulators

To: w8ji@contesting.com
Subject: Re: Topband: Fw: 25G insulators
From: Earl W Cunningham <k6se@juno.com>
Date: Sat, 30 Aug 2003 09:14:18 -0700
List-post: <mailto:topband@contesting.com>
Tom, W8JI wrote:

"With 1500 watts from a 50 ohm line into a series capacitor, line current
(5.5 amperes) times reactance equals RMS voltage across capacitor. A 300
pF capacitor set at 120pf (736 ohms X) would have 5.5*736=4040 RMS or
5724 volts peak."
==========
A shunt feed capacitor value of 120pF on 160m would be needed if the
electrical height of the structure was between 3/8 wave and 1/2 wave
(closer to 1/2), and yes, the voltage across the capacitor would be quite
high.

If the structure was 1/4 wave electrically, the tuned value of the
capacitor would be about 650pF (134 ohms X), therefore the voltage with
1500 watts would be 5.5*134=737 VRMS.

As I said in my previous post, "typically about 700 volts with 1000 watts
applied".
 
73, de Earl, K6SE
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