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Chapter 4 Features and Functions
HP 34901A 20-Channel Multiplexer
HP 34901A 20-Channel Multiplexer
This module is divided into two banks of 10 channels each. Two additional
fused channels are available for making direct, calibrated dc or ac
current measurements with the internal DMM (external shunts are not
required). All 22 channels switch both HI and LO inputs, thus providing
fully isolated inputs to the internal DMM or an external instrument.
When making 4-wire resistance measurements, the instrument automatically
channel n with channel n+10 to provide the source and sense
pairs
connections. The module has a built-in isothermal block to minimize
errors due to thermal gradients when measuring thermocouples.
Backplane Switches
Internal
DMM Input
98
Reference
99
Junction
Sensor
Internal
DMM Input
(4W Sense)
97
Internal
DMM Input
(Current)
96
NOTES:
Only one of channels 21 and 22 can be connected to the internal DMM and/or Com at a time;
connecting one channel will close the other (thus shorting the input "I" to "LO").
If any channels are configured to be part of the scan list, you cannot close multiple channels;
closing one channel will open the previously closed channel.
164
Channel Switches
Bank Switch
Shunt Switches
Fuse
21
95
Fuse
22
01
10
Com
Com (4W Sense)
11
20
21
Current Channels
22
Com (Current)
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