HP 85020A Operating And Service Manual page 26

Operation
Model 85020A/B
3. Perform an OPEN/SHORT calibration as follows:
Press 8756A MAIN MENU soft keys [CAL] [OPEN/SHORT] [CHAN 1].
Connect the calibrated short to the test port of the 85020A,
and press [STORE SHORT] to store the short calibration data.
Remove the short and connect the shielded open to the test
port. On the 8756A press [STORE OPEN] to store the open
calibration data. On the 8756A Channel 1 press [DISPLAY] until
M-MEM is selected. The Channel 1 normalized trace will be
displayed.
4. Remove the shielded open and connect the 10-dB Attenuator to
the 85020A test port. Leave the other end of the attenuator
unterminated.
5. On the 8756A press [CURSOR]. The return loss of the
unterminated pad (10 dB in each direction) will be displayed.
The display should read -20 dB + 2dB.
Figure 3-2. 85020A Operators Check (2 of 2)
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