[ARC5] Vintage test equipment?

[D. Platt]

In reviewing the alignment procedures and maintenance practices, etc. 
for the SCR-274-N and ARC-5 equipment, I'm curious what test equipment 
they (the military) had at the time and, in fact, used for the 
aforementioned?  I know that the early scopes were present, although not 
"calibrated" as we know it today.  I also know the BC-221 and LM were 
readily available, of course.  Also, fairly accurate voltage measuring 
equipment, to include, I believe, VTVMs (which would provide high 
impedance measurements).  I suppose that the standard 20k/v multimeters 
would obviously have been available. Finally, signal generators, too.  
The thing is, accuracy and precision is my real question.  I don't think 
that the military had quite the PMEL functions available today.  How 
good were the test sets out in the field?  Boiling it all down, I read 
the procedure in the maintenance manuals for the above radio sets, in 
particular the receivers and their alignment and test. _If I'm 
interpreting things correctly_, the procedure for measuring receiver 
bandwidth was one where, instead of setting up a reference on the 
desired frequency and moving a calibrated signal generator up and down 
or sweeping the bandpass, they (Navy and Army) used a method whereby the 
signal generator was set on frequency and the receiver was tuned above 
and below the set frequency (or was it the reverse?)  Anyway, by 
increasing the signal generator levels in discrete steps up to values 
representing from 6db (2x) to +60db (1000x) from the reference, the 
receiver (or generator?) was off-tuned until receiver output was seen to 
drop to the original set level.  Of course, the method does work, no 
question, and by using fairly accurate (and measurable at the time) high 
levels, the results could be considered good.

Does this seem reasonable to all of you?  Again, other then the LM and 
the BC-221, what other "standard" RF and measurement test gear was in 
use from '42 thru '45?

Inquiring minds ask.......

Jeep K3HVG