HP 8560A Service Manual page 410

3. Connect a signal source to A15J801 and set the source to the following settings:
Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310.7MHz
Amplitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -30 dBm
4. Use an active probe with another spectrum analyzer to measure the signal at A15TP601.
The signal should measure -18 dBm f2 dB confirming the operation of the 2nd IF
Amplifier.
5. Use an active probe with another spectrum analyzer to measure the 300 MHz into the
mixer's LO port (A15TP602). The signal should measure at least -l-7 dBm.
6. Measure the power of the mixer's 10.7 MHz IF output (A15TP603). The signal level
should be approximately -24 dBm.
7. Move the A2 Controller Assembly's WR PROT/WR ENA jumper to the WR ENA
position.
8. While measuring the signal at TP603, adjust the signal source until the level of the 10.7
MHz IF is -40 dBm.
9. Set the HP 8560A to SINGLE mode.
Increase the gain of the Flatness Compensation Amplifiers to maximum by entering #255
using the data keys. This sets the attenuators in the Flatness Compensation Amplifiers to
their minimum values.
11. Connect the other spectrum analyzer to A15J601 and measure the 10.7 MHz IF signal
level. The signal should measure approximately -10 dBm. If the signal level is incorrect,
continue with step 13.
12. Enter #0 into the HP 8560A Flatness Data. The signal level at A15J601 should measure
less than -32 dBm. This sets the gain of Flatness Compensation Amplifiers to a
minimum (attenuators to maximum attenuation). If the signal level is incorrect, continue
with step 12.
13. Check that the gain stages are properly biased and functioning.
14. Check the attenuator stages and Flatness Compensation Control circuitry.
For maximum gain (Flatness Data equals 255), RF GAIN (A15J901 pin 2) should be
at i-4 Vdc and the current through each attenuator section as measured across R606 or
R614 should be about 7 mA.
For minimum gain (Flatness Data equals 0), RF GAIN (A15J901 pin 2) should be at 0
Vdc and the current through each attenuator section should be close to 0 mA.
Caution As long as the flatness data just entered is not stored, the previously-stored
flatness data will be present after the power is cycled.
15. Move the A2 Controller Assembly's WR PROT/WR ENA jumper to the WR PROT
position.
16. Reconnect the cable to A15J801.
11-12 RF Section
(CAL), MORE 1 OF 2, SERVICE CAL DATA
and FLATNESS.