Dear James,
If these tubes are available, I'll find them.
Since these tubes are *probably* not SAE specific,
there must have been other applications. If it can
be determined what else the D7-200GH was used in
it might lead to a supply. Maybe a compact military
oscilloscope, for example.
This tuner has aged quite well. All power supply
electolytics have survived with very little leakage.
Only an electrolytic capacitor on the relay board has
drifted slightly out of spec.
Since the parts are dated 1971, this is excellent
performance.
Best regards,
Paul Bigelow