[Milsurplus] RF Ammeter Question

[Mark K3MSB]

Thanks John.

I'm using just an old C battery.  The meter reads OK regardless of the
polarity of the battery,  but the reading is different by almost 2:1
depending upon the polarity.  Is that normal?

Mark K3MSB

On Sat, Dec 1, 2012 at 2:48 PM, J. Forster <jfor at quikus.com> wrote:

> You can easily tell if the thing has an internal shunt by running some DC
> current through it and a series limiting resistor, first one way, then the
> other.
>
> If the meter indicates positive, irrespective of the current direction, it
> has a TC.
>
> If the meter reads upscale one way, and downscale the other, it has no TC.
>
> You can also apply 60 Hz AC through a resistor. If it indicated upscale,
> it has a TC.
>
> The meter should have response from 50 Hz to 10s of MHz roughly.
>
> It is odd to see a current meter with a resistor paralleling the terminals.
>
> -John
>
> ============
>
>
>
>
> > I rescued what looks to be a perfectly good Simpson RF Ammeter from the
> > clubs trash can a while back.  It’s a 3 inch square panel meter, 0 to
> > 2.5A,
> > logarithmic scale,  with a 0.05 ohm 25W resistor solder to the terminals.
> >
> >
> >
> > I’m not sure how to tell if this has an internal thermocouple.  I did
> some
> > web searching and it seems Simpson did make these types with the internal
> > thermocouple, but I haven’t found anything that tells how I can verify.
> >
> >
> >
> > I’ve never used an RF Ammeter before, so I assume I use it just as a good
> > old DC Ammeter?   Is there a frequency limitation?
> >
> >
> >
> > Thanks
> >
> >
> >
> > Mark K3MSB
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