Tektronix 067-0883-99 Instruction Manual page 37

UNIVERSAL LOAD UNIT
2. Apply: +10.00±0.01 VDC to the EXT. IN center conductor.
(with respect to chassis ground)
Measure: Between chassis ground and the front rotor. of the
10th wafer of the CHANNEL SELECT switch (see Fig.
4-4).
Check: The meter for an indication of between +1.92 mA and +2.08 mA.
3.
Apply: -10.00±0.01 VDC to the EXT. IN center conductor.
Measure: Between chassis ground and the front rotor of the
10th wafer of the CHANNEL SELECT switch (see Fig.
4-4).
Check: The meter for an indication of between -1.92 mA and -2.08 mA.
3.
Channel Offset Null Adjustments
The adjustment procedure which follows is the same for all cells:
1. Set: The VOLTAGE/CURRENT switch to the "Current" position
and the CHOP/SWITCH switch to the "Switch" position.
Apply: No external voltage or signal.
2. (Before each adjustment) Switch: The CHANNEL SELECT switch
to the next position (of positions 1 through 12).
3.
(For each position) Use: The Null Offset Pot indicated in
Figure
4-5
for the channel being adjusted.
4.
(For each position) Adjust: The indicated pot for a U.L.U. DMM
reading of 0.000 ± 2 counts in the least significant digit.
Note: The high current positions (1,2,7,8) may be expected
to "hunt" or "jitter" within this tolerance.
5.
(After adjusting every channel) Verify: The results of
these adjustments by performing the Verification Test at
the beginning of this Section.
4-9