This Hughes circuit is from 1968. Equivalent modern components can be used. The input impedance is 1000 M ohm.
We found this circuit in an old documentation for hams. In it we have the way to use a varicap to...
Found in an 80's documentation this circuit uses an integrated from the uncommon era today. Other...
This circuit is stabilized by a thermistor or NTC with a resistance between 2 and 5k. The signal is...