Just that simple .........for a radio amateur....... sorry guy's
73's Jos
----- Original Message -----
From: "Chuck Counselman" <ccc@space.mit.edu>
To: <TOWERTALK@contesting.com>
Sent: Friday, January 31, 2003 11:40 PM
Subject: Re: [TowerTalk] Antenna Coupler Capacitor Settings
> Here's how to determine when your C-L-C T-network antenna tuner's
> output capacitor (or if you choose, its input capacitor), is fully
> meshed -- without opening the box.
>
> You need a multimeter (like my Radio Shack DMM) or an impedance
> bridge that can measure capacitance at a low frequency, preferably
> below 1 MHz.
>
> Measure between the "hot" and "ground" terminals of the output
> (antenna) end of the tuner. Crank or switch the tuner's inductor all
> the way down to its smallest possible inductance, which would be at
> the end or the extreme setting that you use for the highest
> frequency. The minimum inductance of the coil is probably around one
> microhenry. At 1 MHz or below, this inductance has a reactance of
> about 6 ohms or less. This reactance is negligible in comparison
> with even the smallest possible reactance of the output capacitor of
> a typical antenna tuner. The maximum capacitance of one of these
> cap's is typically 240 pf; the reactance of 240 pf at 1 MHz is -663
> ohms. Therefore, with your meter, you are effectively looking
> directly at the capacitor.
>
> Now turn the knob on the output (antenna) capacitor and watch the
> meter or bridge to find the maximum C.
>
> -Chuck, W1HIS
>
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