Agilent Technologies HP 8719D Service Manual page 228

Check Open Loop Power (HP 8719D/20D Only)
1. Use a power meter to measure power at the R CHANNEL OUT port on the
front panel.
Press [M) SERVXQZ MENU SEIMCE HOlXS SRC AMIST P%Xu
The power should be at least -23 dBm (-18 dBm, Option 007).
The power should be at least -18 dBm (-13 dBm, Option 007).
4. You may have to change the DAC number slightly to achieve a good power
reading. If power is correct, proceed with "Check Al2 Reference."
5.
If the high band power level is lower than -18 dBm, check A55 YIG 1 power
at S2J3.
6. Connect a power meter to S2J3 and measure the DAC num high band values
from about 3200 to 4095.
If the power at S2J3 is greater than 0 dBm, replace the A58 M/A/D/S.
n
If the power is less than 0 dBm, check YIG 1 output power at the A53 end
n
of W6.
7. Power greater than 10 dBm indicates proper power out of YIG at about
4.5 GHz. If the analyzer is not phase locking at this frequency in normal
operation, the problem is with the RF cabling, S2 or S3.
8. If no power is present, refer to "A51 Test Set Interface Power Supplies" at
the
end of this section, to check the bias voltages to YIGl. If the voltages are
correct, replace the YIG.
Check Open Loop Power (HP 8722D Only)
1. Use a power meter to measure power at the R CHANNEL OUT port on the
front panel.
The power should be at least -32 dBm (-27 dBm, Option 007).