[R-390] R-390a meters

[Joe Foley]

--- mparkinson1 <mparkinson1 at socal.rr.com> wrote:

> How can you really test what the resistance is on
> the sub 1Ma meter?
> I have several of them I did put it into the R-390a
> receiver to test it and it seems to work very well.
> I compared it to the original meter watch both
> working at the same time and frequency and didn't
> see any difference.
> But would like to know how to test the internal
> resistances of the movement.
++++++++
Well,

You would do the 1/2 scale method.  That is you put a
high-value pot in series with the meter and a
low-value pot, those in parallel.  Then you put a
small DC voltage acrossed that set-up and set the
high-value pot to the point where the meter reads full
scale, then you set the low-value pot to where the
meter is at 1/2 scale.  The resistance of the
low-value pot is now equal to the DC resistance of the
meter.

Joe


		
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