[Amps] Calibrate a panel meter?

[Bill Turner]

ORIGINAL MESSAGE:

At 07:24 PM 12/28/2005, wc6w at 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


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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