(Nov 19 2012)

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MGF1425november. Directly from drain to the source ground plane is a RC link 10pF/100 ohms. The wire from the drain to the output side is routed through a small ferrite tube that adds a resistive loss of 3 ohms on 144 MHz and 11 ohms on 1296 MHz.

The drain wire goes to a phase inverter with 2x3 turns on a BD 3.5/1.3/6-4S2 ferrite tube. The midpoint is not grounded but connected to ground through a 40 pF trimmer. This trimmer is used to set the phase correctly to get a deep minimum in the reverse signal.

The drain voltage is set with a potentiometer followed by an emitter follower to 2.20 V. The source resistance is set to 31 ohms with another potentiometer which gives a current of 17.3 mA through the transistor.

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MGF1425november. Input impedance and forward gain.

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MGF1425november. Output impedance and reverse isolation.

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