[volt-nuts] HP 3458A DC current accuracy

[Mike S]

On 7/11/2012 5:15 AM, Frank Stellmach wrote:
> This is the worst realized electrical unit, i.e. the 'mise en pratique'
> is difficult to an error level of about 1e-7 only.

On 7/11/2012 6:50 PM, Bob Smither wrote:
> I may be off here, but I doubt that thermal (Johnson) noise would limit the
> precision of current readings.
> A one ohm resistor in a 1 Hz bandwidth would be 0.13 nV or 0.13 ppm of the 1 mV
> reading.

It seems you just showed that it does (limit the precision).

-- 
Mike