HP 8508A - Page 84

Adjustments
To equalize the A and B Channel phase shift.
DESCRIPTION
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- An internal test routine is used for this adjustment.
EQUIPMENT
No external test equipment is required for this adjustment.
PROCEDURE
1. Remove the Input Module from the instrument.
2. Switch on the equipment and allow to warm up for 30 minutes.
Note: Since the Input Module is not installed in the mainframe, the HP 8508A will display the error
message “Err 601”. This reading should be ignored.
3. Remove the HP 8508A top cover to allow access to the adjustments.
4. Set A3R151 fully counter-clockwise.
5. Select [PRESET] [SHIFT] [POWER MEAS] to put the i instrument into the ‘setup’ mode. The Pupley: will now
indicate which setup code is being used. It will appear as:
tSt nnan
tSt indicates that the instrument is in the ‘ setup’mode and’ nnnn’ is the current setup code.
Use the UP/DOWN ‘Arrow keys to set up test code ’4’ in Display 2.
Press [HOLD VALUE] and check that the indicator lamp is illuminated.
6. Adjust A3R151 to obtain a zero reading in Display 2.
7. Press [HOLD VALUE] to cancel the function.
8. Replace the HP 8508A top cover.
5-8
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