[Amps] Fw: Calibrate a panel meter?

[ZL2AAA]

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Subject: Re: [Amps] Calibrate a panel meter?


The easy way to do this is to hook up a 1.5v battery in series with about a
100ohm ww pot. connect the meter to be calibrated in series with this
combination and  a known meter or a multimeter.In other words the whole lot
in series noting polarity.With a nicrome wire or thin fuse wire shorted
across the meter to be calibrated adjust the pot for a reading on the
multimeter.Adjust the pot and the wire until both the meter to be calibrated
and the multimeter read the same.A low voltage adjustable power supply may
be used in place of the battery pot combination.Hope this makes sense.Morrie

----- Original Message ----- 
From: "Bill Turner" <dezrat1242 at ispwest.com>
To: <amps at contesting.com>
Sent: Thursday, December 29, 2005 7:20 AM
Subject: [Amps] Calibrate a panel meter?


I have a Simpson 923A panel meter, 1 amp full scale. It is reading
low by about 6%. When it has 800 ma through it, it indicates about
750 ma. I'll be using it in my 8877 amp at 800 ma and I'd like it to
be more accurate.

If it were reading high, I could just shunt it, but reading low...???

Is there a way to calibrate it by adjusting anything inside? Moving
the magnets around, etc? I'm sure the factory calibrates them somehow
but I've never read anything in the ham literature about how to do it.

Suggestions appreciated.

73, Bill W6WRT

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