[R-390] Re: panel meter resistance

[W. Li]

>From: "AI2Q" <ai2q@adelphia.net>

>Why not use a DMM (never a VOM!) and simply measure the internal resistance
>directly.  Works like champ using a Fluke 8020A.

One caveat: be sure that you measure the maximum current put out by your
DMM on the ohms function before you measure your unknown meter. My Fluke
8120B put out only 350uA with the leads shorted on the 0-200 ohm
setting, so it was safe to measure directly the internal resistance of a
R390 carrier 1000uA meter. But if I wanted to measure the resistance of
a 50uA meter with an estimated resistance of say, 1200 ohms, my DVM put
out 950uA on the 0-2000 ohm setting, 14uA on the 0-20K ohm setting, and
14uA on the 0-200K ohm setting. Clearly, it would be foolish to use the
0-2000 setting, but safe to use the 0-20K or 200K settings. YMMV of course,,,,,

Wayne