HP 70427A User Manual page 131

Downconverter Operation
AM Noise Measurement (Input AM Detector) System Control
Step 4 - Measure the AM detector's output voltage
The detector's output voltage is measured with the downconverter's internal
voltmeter.
1. Read the
AM DET Voltage:
2. Press the HP 3048A
3. Press the HP 3048A
4. Repeat from step 1 until the reading on the
doesn't change from one reading to the next.
5. Record the final reading for use in the next step.
Step 5 - Measure and adjust the calibration source power
Connect the calibration source's output to the downconverter's SIGNAL
input. Set the calibration as follows:
•
Frequency:
IF DUT frequency is <500 MHz: Use the DUT frequency.
IF DUT frequency is >500 MHz: Use the 500 MHz (if the cal source
can tune the DUT frequency use the DUT frequency).
•
Power: +10 dBm
•
Modulation: OFF
Adjust the calibration source power so that the voltage measured at the
output AM detector is within ±5% of what it was with the DUT connected
to the downconverter.
1. Read the
AM DET Voltage:
2. Press the
READ AM DET
3. Press the
READ AM DET
4. Repeat from step 1 above until the reading on the
display doesn't change from one reading to the next.
5. If necessary, increment/decrement the calibration source's output power.
6. Repeat steps 1 through 4 above to read the detector's output at the new
power.
7. Repeat steps 1 through 5 above until the calibration source's detector
voltage is within ± 5% of the DUT's detector voltage.
3-32 HP 70427A/HP 70428A User's Guide
display.
softkey.
Update AM Det.
softkey again.
Update AM Det.
AM Det Voltage:
display.
softkey.
softkey again.
display
AM Det Voltage: