3458A AZERO function not working ?

[opa627bm]

Hi all,
I have a brand new 3458A from Agilent, never been used.
We just realized that the meter hold zero better without Azero function enabled.
is that normal?
with Azero enabled i have 0.00040mV offset, with Azero disabled, i only have 0.00010mV offset when input are shorted...
Regards,
Li

[Kleinstein]

The should be no significant offset in AZ mode. The 4 µV measured offset could however be from thermal EMF. So the type of cable can make a difference. The easiest good solution is probably a piece of bar copper wire - not using banana plugs.

It may be just by accident that an external offset and the offset from the non AZ mode does cancels out.

Another point can be that a new meter may need a call to ACAL is little more frequent for the first 2 weeks or so.