Hello!

I have a problem with reading the specifications on 438A power meter

The zero set spec. is "+/- 0,5% of full scale on most sensitive range. Decrease percentage by factor of 10 for each higher range +/- 1 count." I am a little confused with the +/- 1 count is this the resolution of the meter?

i.e. at 1 mW range 3 (auto filter) will the worst deviation be 0,005% of 1 mW multiplied with the resolution 0,001 mW equals 0,00105 mW?

When calculating the uncertainty of the measurement will the resolution of the meter be a separate component or is this already included with the +/- 1 count specification on the zero set?

Thanks!

I have a problem with reading the specifications on 438A power meter

The zero set spec. is "+/- 0,5% of full scale on most sensitive range. Decrease percentage by factor of 10 for each higher range +/- 1 count." I am a little confused with the +/- 1 count is this the resolution of the meter?

i.e. at 1 mW range 3 (auto filter) will the worst deviation be 0,005% of 1 mW multiplied with the resolution 0,001 mW equals 0,00105 mW?

When calculating the uncertainty of the measurement will the resolution of the meter be a separate component or is this already included with the +/- 1 count specification on the zero set?

Thanks!

yes, it means +/-1 count in the least significant digit using the current resolution.

>When calculating the uncertainty of the measurement will the

>resolution of the meter be a separate component or is this already

>included with the +/- 1 count specification on the zero set?

the 1 count uncertainty is usually much smaller than, and absorbed into, the "instrumentation accuracy" spec.