Silver mica cap

[Alex KL-1]

The 1N34 are not too reliable for capacitance changing since it are constructed with a different juncion tech (ir more like like a Schottky-like; some metal-to-N type semi). Even a common silicon diode are more suitable here. But is a matter to discover it's code and find some compatible type.

[timmy]

Originally Posted by Alex KL-1

The 1N34 are not too reliable for capacitance changing since it are constructed with a different juncion tech (ir more like like a Schottky-like; some metal-to-N type semi). Even a common silicon diode are more suitable here. But is a matter to discover it's code and find some compatible type.

But it may work?

[Alex KL-1]

Perhaps it will kill the tuned circuit and not work (is there some risk). Depending how it is wired in the circuit. The low forward voltage of it will kill it if it works with low bias. And, will not be effective at action, being too resistive and killing the Q, or not varying the capacitance in the needed range.
I recommend a silicon diode here at least (the first varicap ones are simply some selected diodes from another application).