I have a Heathkit HW-9 transceiver which uses two germanium diodes (D308/D308, 1N295) as a voltage reference for the AGC amp (U302, CA3130).

For years I've noticed the S-meter reads up to S5 with no signal input on cold days and have - I think - confirmed this by cooling them with Q-Tips and alcohol and watching the S-meter move.

There are probably lots of ways to improve this (and many other parts!) of the circuit, but would Schottky diodes here be more temperature stable?
Thank you.

 

The forward voltage drop on most germanium devices varies with temperature. That is an unfortunate reality. Certainly posting the circuit will allow a lot of minds to work on the solution.
The TERRIBLE NEWS NOW is tha some "very much for profit" entity purchased the exclusive rights to much, if not all, of the Heathkit manuals and instructions. So for $25 or more you might get what you are looking for.