Now that I can make a crystal oscillate correctly (see Crystal Oscillator (Germanium Edition)) comes the other task of tuning the circuits.

I'll receive a FE-5680A at 20MHz (someday) so I'll have a reliabe frequency source. However it's not here now. How do I tune my custom oscillators ?

Looking back at Integrated 32KHz clock source it appears that I already have one semi-reliable clock source: a DS32KHz, rated at about ±2ppm, which is enough for a first rough tune (±0.1Hz or 3ppm seems to be a practical limit).

Now here is the "quick and dirty hack" : hook the DS32KHZ module to the 'scope, let's say chan A, then the DUT (Design Undertaking Tuning) on chan B. Set the trigger to chan A and play with the knobs... The signal being tuned should not dance anymore, if you play well.

Well, with Germanium transistors, the leak is VERY sensitive to temperature so even touching a transistor slightly will detune it. Give the circuit some time to reach thermal equilibrium...

Aaaaand I started https://hackaday.io/project/10846-scopebase to get a proper tool for these manipulations :-D