In the late 60's I made a coaxial capacitor from a length of RG-17 to supply
most of the C for a 40M Bobtail. A little too big to fold and the losses
were not even worth thinking about.
On 160 with a decent coax what would be the effect of a little loss besides
a little heat ?
Carl
KM1H
----- Original Message -----
From: "Richard Karlquist" <richard@karlquist.com>
To: <topband@contesting.com>
Sent: Sunday, September 29, 2013 10:12 PM
Subject: Re: Topband: Homebrew capacitors
On 09/29/2013 07:42 PM, Jim GM wrote:
Could have saved more money with a Piece of RF-9913 or RG8 coax cable
about
25pF per foot plenty voltage rating.
Only thing can some one please help me on this, do I connect the center
conductor on one end of the cable and use the shield on the other end?
Or
just use the center conductor and shield on one end, while the other
end
are floating not used and not tied together?
Neither. Instead fold the coax and connect to both ends in parallel.
IOW, connect the center conductors in parallel and the shields in
parallel.
This will greatly reduce the loss due to the resistance of the conductors.
Constructing a capacitor out of coax is a suboptimal topology, but folding
it
and connecting the ends in parallel at least mitigates the loss.
Rick N6RK
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