Topband: Homebrew capacitors

[ZR]

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 at karlquist.com>
To: <topband at 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
> _________________
> Topband Reflector
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