If you are only concerned with tuning out the inductive reactance, a series
capacitor can be chosen for that purpose. The resulting Z of the antenna then
becomes 41.2Ω +j0 and the SWR drops from about 12:1 to about 1.2:1.
The equation is derived from the formula for capacitive reactance: Xc =
1/(2*Pi*F*C)Solving for C, the equation becomes: C = 1/(2*Pi*F*Xc).
If F = 1.9 MHz and Xc = 139Ω, then C = 603 pF
Don't ignore the voltage across this capacitor, for a KW, that voltage will be
the better part of a kilovolt
-Mike-WA6ZTY
From: Richard Thorne <rthorne@rthorne.net>
To: Towertalk <towertalk@contesting.com>
Sent: Monday, November 7, 2016 9:48 AM
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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