[Boatanchors] Meter Resistance Measurement

[jmfranke]

Not sure if they are the best methods, but I use either of two methods:

The first is to feed the meter with an adjustable power supply through a 12K 
resistor to get a full scale deflection. The correct voltage will be around 
12V. Then, I measure the voltage drop across the meter. The meter resistance 
is simply V/R or V/.001. So, for a meter movement with 50 Ohms resistance, I 
will expect 50mV across the meter.

The second is to get a full scale deflection and then parallel the meter 
with an adjustable resistor. The adjustable resistor is varied to get half 
scale deflection. The adjustable resistor is then removed and measured with 
an ohmmeter. It's resistance is now the same as the meter resistance.

John  WA4WDL
--------------------------------------------------
From: "Richard W. Solomon" <w1ksz at earthlink.net>
Sent: Friday, May 25, 2012 1:24 PM
To: <boatanchors at mailman.qth.net>
Subject: [Boatanchors] Meter Resistance Measurement

> What's the best way to measure the internal resistance of a 1 mA DC Meter 
> ?
>
> I recall an old Handbook showed a way, but that book is no longer here.
>
> 73, Dick, W1KSZ
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