2461Type C User Manual
Racal Instruments
1998
Performance Verification and Adjustments 6-7
instructions as presented by the program.)
11. Verify that the 2461 is not counting. If it is, repeat steps 7
to 12, (i.e. follow the instructions as presented by the
program.)
12. When satisfied that the setup is complete press “Stop”
followed by “Close”
13. Switch off the VXIbus mainframe. Disconnect the test
equipment.
Alternatively, if the setup program is not available, use the
following procedure:
1. Follow steps 1 to 4 above
2. Using an appropriate VISA interactive control program send
the following commands to the 2461C:
“CAL:STAT ON”
“CAL:DATA? NVM,25” and read back the response
Bitwise “OR” this value with 4 to produce “new
value” (for example use the calculator within WIN
NT, WIN95, etc)
“CAL:DATA NVM,25,<new value>”
“CAL:STAT OFF”
This will have set the “Channel 3 Fitted” flag in the non-
vol memory of the UCT.
3. Start the 2461 soft front panel application program (Racal
Instruments Limited, p/n 60-0084 and 60-0087) and select
the UCT.
4. Select “Frequency, Input 3”
5. Select “Configure > Reference > Frequency Standard”;
choose “External” and press “Apply” then “Hide”.
6. Select “Continuous” measurement mode.
7. Set the signal generator output to 1GHz at 10.0mv rms
8. Adjust R27 counter-clockwise until the measured reading
just starts displaying 1.00009
±
0.000000001
(Turn R27 very slowly to prevent over-shooting the correct
adjustment.)
9. Switch off the RF output of the signal generator and reduce
the output level to 8.5mV rms
10. Switch on the RF output of the signal generator and verify
that the 2461C is not counting, i.e. displays
99.000036. If it is still counting repeat steps 7 to
10.
11. Switch off the VXIbus mainframe
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