[Boatanchors] d'arsonval meter question

[J. Forster]

Sometimes, meters have a small piece of iron held by a screw that shunts the air
gap and is used to adjust the H field and hence  the calibration. If the thing
was bashed, that shunt could have moved, altering the calibration.

FWIW,
-John



E C Moxon wrote:

> Hi all.
> I've got an old hp 723a supply whose meter movement seems to be out of
> whack. The meter housing has been busted for many years, but the movement
> seems to move smoothly, no sticking. Its just that the deflection is about
> 12% low on all 3 voltage ranges (seen at midscale, fullscale). The
> multipliers are all measuring better than 1%
>
> So the question is, what kinds of things would account for overall reduced
> sensitivity? It's a 1-mA 50-ohm movement. I'm not too hopeful that it will
> turn out to be anything I can fix, but I'm curious.
>
> Ed, K1GGI