ORIGINAL MESSAGE:
At 07:24 PM 12/28/2005, wc6w@juno.com wrote:
>Hi Bill,
> I believe that meter is in the 50 mV family -- You can confirm
> this supposition by measuring the voltage drop at 1A (full
> scale). The intrinsic movement is likely 5mA.
>
> Inside the meter, you should encounter a small series R, slightly
> less than ten ohms, connected from one end of the shunt to the
> coil. Shunt this R with something around 100 ohms (perhaps, a 200
> ohm trimpot?) and you should be able to bring the meter back into calibration.
>
>73 & Good evening,
> Marv WC6W
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Exactly right. The resistor was marked 8.1 ohms, and a 68 ohm in
parallel made the calibration accurate within the width of the
needle. Can't ask much better than that!
Many thanks Marv, and to all who responded. What a great group!
73, Bill W6WRT
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