4 MHz Oscillator Picture

Notice the feedthrough cap at the middle top for 12 Volts. The 60pf trimmer in the schematic is not included in this circuit.

The crystal is 4 MHz in one of the old style cans mounted in a crystal socket. The newer smaller surplus computer crystals will work just as well.

Be sure to ground the tab on the variable trimmer that connects to the adjustment screw, or it will be difficult to tune the oscillator, unless you use an insulated tuning tool. Most plastic tuning tools will quickly tear up after making a bunch of adjustments on these trimmer caps.

The other tab of the trimmer cap is bent up to connect to the rest of the circuit.

Output is at the middle right going into the diode mixer.