[volt-nuts] Voltmeter calibration

Bob Albert bob91343 at yahoo.com
Sat May 31 01:15:08 EDT 2014

I recently acquired an HP 3456A which has a tighter specification than 
the EI.  It's also a couple of decades newer and has been calibrated.

So I took a deep breath and opened the EI looking for a calibration 
adjustment.  I found one, and tweaked it to bring the EI back into 
specification.  It was off by about 0.06% and now it's within its spec 
of 0.01%.

Pretty good gear, to hold its calibration so well for about a half century!  And now it has a new lease, with its recalibration.

I also monitored the EI to see what its warmup time is.  It settled very 
closely within about 15 minutes from a cold start.  And I mean cold; I 
hadn't switched it on for quite a while.  (There is a 55C oven in it, holding the reference temp 

Of course I don't need this unit any more but it's quaint and works 
great.  It's not all that much bigger than the HP but lacks the 
resistance measurement and a few other bells and whistles.  And the big Nixie tube readout is cool.


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