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Re: [TowerTalk] Capacitor Value for a 160m T antenna

To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] Capacitor Value for a 160m T antenna
From: "Paul Christensen" <w9ac@arrl.net>
Date: Mon, 7 Nov 2016 14:12:51 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Xc=1/(2*Pi*f*c)

For 1825 kHz, C = 628 pF, leaving 41.2 +j0.  

But, that doesn't get you to Zo = 50.  But this does...

Hi-Pass L option:  285 pF series C with 6.1 uH shunt across Zo=50 input
side;  loss = 0.02 dB with QL = 200.

Or...

Low-Pass option:  574 pF shunt across load, 6.8 uH series L; loss = 0.09 dB
also with QL = 200.

Both answers assume high quality caps with very high Q and coil Q at least
200.

Paul, W9AC



-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
Richard Thorne
Sent: Monday, November 7, 2016 12:48 PM
To: Towertalk <towertalk@contesting.com>
Subject: [TowerTalk] Capacitor Value for a 160m T antenna

I'm going to build a T antenna for 160 in a few weeks.

I need a capacitor to tune out z = 41.2 + j139.

For the educational experience, how do I calculate a cap for the above
equation?  I'm going to try and track down a variable cap for the above so I
can build the antenna over the Thanksgiving holiday.

Thanks

Rich - N5ZC

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