Ancient_Hacker wrote:
I don't have the manual anymore but IIRC it didnt take much circuitry.
Your basic R-C blocking oscillator is more than happy to sync up to
anything. That only requires one tube.

It was probably a way of measuring time durations on a scope with
uncalibrated and not terribly linear sweep.

I had a USN24C back in the early 70's and was sorry to lose it to a
shorted power transformer after only a few years of use. It was the
best I could afford back then.
Cheers, Hank