This circuit for medium and short wave range was found in an American documentation from 1992. The circuit can use general purpose transistors and the antenna can be external or telescopic.
In the figure we have the way to use a single control voltage to act on two varicaps...
This oscillator provides a 1 MHz rectangular signal determined by the capacitors used. The circuit...
This shield circuit with an optical coupler was found in an 90s EDN. The circuit can be used with...