(Nov 19 2012)

MGF1425narrow. This amplifier was built 1993 and used together with an identical one with cross yagis until yesr 2000. It was modified November 2012 when the wire from the antenna connector to the input coil was moved a little further away from ground. This change reduced the NF by about 0.2 dB. No other changes have been made. The 100 ohm resistors that are grounded in both ends serve the purpose of loading the microwave cavities formed when the lid is closed. Without the resistors there are microwave oscillations. Today I would load the drain with a series RC link 10pF/100 ohms (144 MHz) to the source ground plane and put a very small ferrite tube in series with the output. Neutralization is by a link on an air would coil. That gives good neutralization since the RC link and ferrite tube is not used in this amplifier. Those components would give a phase shift that would need to be compensated. DC bias is by two series connected LEDs operating as a zener diode giving 3.34 V on the drain. The emitter resistor is fixed at 36 ohms which gives a drain current of 13.6 mA.

MGF1425narrow. Input impedance and forward gain.

MGF1425narrow. Output impedance and reverse isolation.