Friday, October 29, 2021

Active antenna for shortwave

This little circuit is a start point for an active antenna.
I labeled some tie pints to help with the hookup.

The gain is good.
Look at the current drain. (as designed)
Subbing a J112 increases the current drawn but the gain is still about the same.
Checkout the frequency response. My target is 3 - 10 meg. Ok for that range? Using a J112 here.

Using the 2SK2539 reduces the current draw. You could use any JFET but the performance will vary.

What would happen if we vary R13, R14 and C9?

What would happen if we vary R16, R17 and C12?

Does it need a RF gain pot?


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