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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