Tuning a 2n3819 jfet drain in common source configuration at 50 ohm receiver input stage.This circuit has been built and tested.
Transformer :
PRIMARY WINDING: 0.5 mm enamelled wire, 29 wounds onto a 23mm diameter cardboard tube.
SECONDARY WINDING : same size wire wound over the primary one at ground side.
My suggestion is to use a good quality air variable capacitor (50pF) to match the best tuning.
Return loss at the input 10 K side is close to 18 dB. This requires a fine and delicate manual tuning.
