[Boatanchors] Meter Resistance Measurement

[jmfranke]

Ops, make that V/I not V/R.

--------------------------------------------------
From: "jmfranke" <jmfranke at cox.net>
Sent: Friday, May 25, 2012 1:39 PM
To: "Richard W. Solomon" <w1ksz at earthlink.net>; 
<boatanchors at mailman.qth.net>
Subject: Re: [Boatanchors] Meter Resistance Measurement

> 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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