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Power measurement with 432A and 478A

Question asked by bar28 on Sep 22, 2010
Latest reply on Sep 23, 2010 by bar28
I'm trying to measure precisely E4417A power meter's 50 MHz/1mW RF reference output using HP 432A power meter with 478A thermistor mount.
I have followed 432A's user guide note how to make precision power measurement taking account those Vcomp and VRF voltages. I have one
Agilent 34401A DVM for that purpose. Main problem is that those Vcomp and VRF values are not stable even i have made Coarse and Fine zeroes for the meter.
All equipment's locates temperature stable laboratory (23 +/ 1 celsius). Many user guides says to use more precisise Agilent 3458A DVM. Is 34401A still enought precise for those Vcomp and VRF measurements?

Should i take account something special how to zero 432A meter first and how to connect those Vcomp and Vrf output's to 34401A voltage inputs? I have only one DVM where i have connected Vrf to DVM's rear input and Vcomp to front input connectors using BNC cable's where another end has suitable banana connectors.

If someone have practical hints or advices for such a precision power measurements, please let me know.