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A practical way to determine the value of the compensation capacity.

I have used an adjustable capacitor with a value between about 5 and 60 pF.



Now you can change the capacity until you have the best behavior on the desired frequency.


Example:

Situation without compensation:


If you want to do an optimization for 7,200 MHz:

Change de capacitor value until you have the best SWR on 7,200 MHz.



This is the result.

SWR < 1.05 on on 160, 80 en 40 meters>

SWR < 1.05 on 1.8, 3.8 and 7.2 MHz


Now measure the value of the adjustable capacitor and replace it by a cpacitor with the same value>


However, the capacitor must be able to withstand the high voltage depending on the transmitting power used. This is very important.



Same exercise for 14 MHz:

Capacitor is changed for best SWR @ 14MHz



This is the result.

SWR < 1.05 on on 160, 80 en 40 meters>

SWR is 1.09 @ 14 MHz MHz


Now measure the value of the adjustable capacitor and replace it by a cpacitor with the same value>


However, the capacitor must be able to withstand the high voltage depending on the transmitting power used. This is very important.


Same exercise for 30 MHz:

Capacitor is changed for best SWR @ 30MHz



This is the result.


SWR is 1.35 @ 30 MHz

SWR < 1.35 @ lower frequency


Now measure the value of the adjustable capacitor and replace it by a cpacitor with the same value>


However, the capacitor must be able to withstand the high voltage depending on the transmitting power used. This is very important.



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