There is a simple way to avoid this problem which I have used many times
through the years. If you need a value near 0.3 ohms for proper calibration,
use a standard larger value resistor such as 1 or 5 ohms in the current path.
Then use a series resistor to one of the meter leads to bring the setup into
calibration. It will be a resistor of reasonable value which can be measured
with your Fluke. You can calculate the values if you wish but I usually use a
metered current source .Place a resistance substitution box in series with the
meter to be calibrated. Vary the box until you get the right meter deflection,
then solder in a fixed resistor of the proper value. You can do this faster
than I can describe it. All of the necessary parts are availabe at Radio Shack
if your junk box doesn't have them You don't even need to know the meter
internal resistance with this method. 73, Dan, N5AR
zeitler@ibm.net wrote:
> Gents,
> Is there a simple way to accurately measure the low resistance of a current
> meter shunt? I am trying to get my plate current and grid current meters
> calibrated and I need to verify the values of the shunt R but the Ip shunt
> is less than .3 ohms and the Ig shunt is less than 1.6 ohms. My Fluke 77BN
> is of no real help at these low values.
>
> Lane Zeitler
> Ku7i
>
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