[Milsurplus] Precision resistors in WW II gear

[WA5CAB at cs.com]

John,

I was following that thread.  The simple answer to your question is yes, most 
resistors in voltage, current and resistance measuring equipment were 1%.  
Combination instruments, like for example the I-135 test set for the BC-611, 
used 1% meter multiplier and shunt resistors but 10% or 5% (depending upon year 
of manufacture of the particular model) in the modulator and crystal test 
oscillator.

But with regard to calibrating a TV-7, if the calibration settings were 
developed for use of a 1000 ohm per volt voltmeter, then someone else's and then 
your suggestion of shunting the available 20K ohm per volt instrument to 1000 
ohms per volt is perfectly valid.  The circuit under adjustment will be unable 
to tell the difference.  And what the voltage at the test point goes to when 
you remove the meter is immaterial.  Assuming that whomever wrote the test specs 
did it correctly, the test specs would have been developed to produce 
satisfactory results after the adjustments had been made, not while they were being 
made.

QED

In a message dated 5/23/2005 11:27:45 PM Central Daylight Time, jfor at quik.com 
writes: 
> Has anyone seen extensive use of 1% or better resistors in WW II era gear? 
> I
> have not, except possibly for some meter shunts.
> 
> The reason for the question is an argument on using 1000 or 20,000 ohm/volt 
> VOMs
> to calibrate a tube tester on another list. The 20K/volt is available, and I
> suggested a shunt to make it 1K/volt. The counterclaim is the accuracy will 
> be
> inadequate, which I do not believe.
> 

Robert Downs - Houston
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