HP34401 low input impedance and maximum voltage question

[harrimansat]

I´m fixing a HP34401, someone with the same multimeter can please check if impedance above 20 volts is 100k?

Attached photo is voltage input at 10V scale 10 Mohms selected, connected at Tektronix 576 curve tracer.

With more of 20V impedance is 100k?

Manual says 1000v max voltage but nothing about impedance.

Thanks

Regards

[Kleinstein]

The input specs are some 100 K beyond some +-17 V for the 0.1 to 10 V ranges. This also makes sense looking at the schematics.

The opening in the center is likely due to the input capacitance.

[rolkinas]

on mine 34401A:
1Vdc to 1000Vdc impedance stays 10 Mohm (input R selected to be 10 Mohm )

1V - 0.1uA
10V - 1 uA
100V - 10uA
1000V - 100uA
(measured with Keithley 237)

Switcing input R to 10 Gohm
it stays high impedance 0-12Vdc
above 12Vdc input R switches to 10 Mohm

[harrimansat]

on mine 34401A:
1Vdc to 1000Vdc impedance stays 10 Mohm (input R selected to be 10 Mohm )

1V - 0.1uA
10V - 1 uA
100V - 10uA
1000V - 100uA
(measured with Keithley 237)

Switcing input R to 10 Gohm
it stays high impedance 0-12Vdc
above 12Vdc input R switches to 10 Mohm

Thanks, but in 1V and 10V scale, with voltaje greater than 17V wich is the impedance?

[rolkinas]

when 10M input impedance in meniu is set, actual impedance at 30Vdc through mV, 1V, 10V ranges appears to be 300kohm

100V and 1000V are steady 10Mohm. Of course 34401A displays OV.LD in lover ranges with 30V on input
Transition from 10Mohm to 300k is at 20Vdc

[harrimansat]

Scale swtiching time and impedance at VDCHI