Quote:
Originally Posted by Bazz4CQJ
Quote:
Originally Posted by Sinewave
Oh and they're valve driven, so even more in keeping with the vintage of our hobby.
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Well, when you recall the kind of "signal generators"  we had in the 1940's to use to align the HRO's and AR88's, it's quite unbelievable that those receivers were of any use at all, or that they could in any way help Alan Turing get his picture of the new £50 note  .
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Somehow, they managed.
They had some rather rough sig gens which worked well enough to fix sets with something dead along the signal path. They had no hope on frequency accuracy
Then they had the gorgeous BC221 frequency meter. An ultra-precision VFO with hundreds of pages of automatically typed individual calibration chart, a crystal reference oscillator giving accurate harmonics right up the band, and then a mixer/headphone amp so you could tune to the reference or an input to correct the table. The tuning knob turned 50 revs across its basic band the knob had a vernier to 1/1000 of a rev.
The BC221 did not do low level sensitivity tests, it did not do modulation. It did frequency accuracy and it did it amazingly well. Other sig gens did mod or were screened well enough to go to low levels. The BC221 could monitor them or calibrate them, but it might be wasted effort if they weren't stabe and repeatable.
They had the means, but it was tedious and took skill
Good modern digital stuff is a walk in the park by comparison.
Poor modern digital stuff can be crap, leaking big amounts of signal, drifting, noisy.
Whichever era you opt for, there is good stuff to be sought and junk to be avoided.
David