[sci.electronics] Queries about moving coil instruments

bill@bert.Rosemount.COM (William M. Hawkins) (06/02/91)

Found some gems at an antique radio swap meet in Minneapolis this
weekend, hence the queries.

Weston Model 155 AC Voltmeter, 500 volts full scale, last patent
date on nameplate is 1898.  It could stand to be refinished, but
I can't see how to disassemble it.  The feet are simply screwed
into the wood; they do not hold the case together.  Anyone know
how to do this?

Rubicon (Philadelphia) light beam galvanometer, model 3402H.
There are slots on either side of the case between the moving
coil and the light source and mirrors for some kind of insert,
but it is missing.  I assume it was a light mask. Anyone know?
(We used to use these to test the bridge wire resistance of
blasting caps at the Hercules plant in Port Ewen, NY, because
of their excellent electrical isolation.)

L&N Catalog # 2500F mirrored galvanometer, with a sensitivity
of .00009 microamps per millimeter spot deflection.  I wonder
how long the light arm had to be?  This did not survive being
carted around in someones trunk without a shunt, or locking
the coil.  Anyone know how I could get it repaired?  The lower
coil support wire seems to be broken.

Any clue as to the dollar value, past or present, of these
instruments would also be appreciated.

Please email, as I have about a 50% probability of seeing a
posting, to bill@bert.rosemount.com

If anything interesting happens, I'll post a summary.  Thanks.