On Tue, 2008-06-24 at 03:24 -0700, Jim WA9YSD wrote:
> Ok, 0.3 watts of insertion loss, right?
>
> Now ANSI specs for pressure gauges are rated Class A,B,C,D. Class D being
> the least accurate, and commonly found on Air pressure tanks and compressors
> to put up car tires or what ever. It is the common gauge.
>
> Now for electronic meters, and it has been a long time for me, the rule of
> thumb is that the accuracy of just the meter is PLUS or MINUS one
> mark/graduation on the meter it's self. So the accuracy tolerance of the
> Bird is less accurate than 0.3 watts.
>
> I use to have some surplus amp meters that had had a mirror right under the
> marks so you could get a dead on reading on the pointer.
>
> Keep The Faith, Jim K9TF/WA9YSD
>
Meters are generally rated with error a fixed % of full scale. Typical
panel meters run 10%, some 3%, lab grade meters 1% or better. That's the
meter alone. The couplers in a Bird add to the error budget. If the
error budget is 3% of full scale, a reading at 10% of full scale has an
error budget of 30% of the reading. The Bird meter is a very sensitive
instrument with a full scale sensitivity of 30 microamps, that makes it
low power and most sensitive to pivot friction or band stiffness if a
taut band movement. The most sensitive stock meters generally have been
50 microamps full scale.
73, Jerry, K0CQ
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