[Amps] More FS items

[Jack/W6NF]

On 7/24/2012 8:48 AM, Vic K2VCO wrote:
> This prompts me to mention that I've used a lot of meters like this on aluminum panels.
> They read low, and it is easy to modify internal shunts to correct them. Often there is an
> internal shunt and series resistor made of resistance wire, and all you have to do is clip
> a bit off the series resistor.
>
> If you need to wind a new shunt, a single strand of steel "picture wire" works.
>
> I check meters by putting them in series with a DVM and a pot and setting the pot to
> produce a reading at the point where I want the most accuracy. Then I adjust the shunt,
> etc. until the meter reads the same as the DVM.
>
> I know this is obvious, but you can't assume that surplus meters will be correct,
> regardless of the kind of panel.
>
> On 7/24/2012 7:45 AM, Jack/W6NF wrote:
>> This meter requires a 50mV shunt*and*  must be mounted on a steel panel
>> for proper calibration accuracy.
The 5 amp FS meter was the plate current meter out of an RCA transmitter 
and it *was* accurate..had to be to meet FCC specs, but only on the 
steel panel. Since I don't have the shunt (well, I *did* but it has gone 
missing) all bets are off :>)

-- 
Jack, W6NF
Silver Springs, NV
DM09ji