HP 70427A User Manual page 127

NOTE
Downconverter Operation
Millimeter Phase Noise Measurement System Control
The Up/Down arrow keys select the parameter, and the Left/Right arrow
keys select the parameters values.
•
Spectrum Analyzer View: IF
•
Microwave/mm band: MM band of the external mixer.
•
Auto/Manual Input Attenuation & IF Gain: AUTO
•
IF Gain: determined by system if Auto is selected.
•
mm Band Mixer Bias ON/OFF: OFF (bias may need to be enabled in
step 3 below)
•
mm Band Mixer Bias: 5 mA (bias may need to be adjusted in step 4
below).
•
Tuning Sensitivity: select the sensitivity determined in step 1above
(if the HP 70427A is being tuned).
•
LO Power: system enters factory default value.
•
Auto/Manual LO Frequency selection: Auto
•
LO Frequency: determined by the system.
•
100 MHz Ref. Chain PLL Bandwidth: use the default, 126 Hz.
•
600 MHz Ref. Chain PLL Bandwidth: use the default, 10 kHz*.
*Unless use of a wider bandwidth is dictated by the tuning sensitivity
and the HP 3048A PLL bandwidth (see step 1). The only reason to use
anything other than the default bandwidth is if the downconverter is
being tuned using 1.0 ppm/V tuning sensitivity and the HP 3048A
system bandwidth is greater than 10 kHz. If the downconverter is being
tuned, the 600 MHzx PLL bandwidth must be wider than the HP 3048A
system bandwidth.
•
System Spectrum Analyzer Connection Port: HP 11848A
Step 3 - Start a new measurement
Connect the sources when the software pause at the connection diagram.
Set the reference source output as follows:
•
Frequency: Same as downconverter's IF.
•
Amplitude: +16 dBm
Now look at the HP 70427A's MMS display. If the message,
, is displayed press the
Adjust mixer bias:
HP 3048A controller. Move the cursor to the
line and select ON. Go to step 4.
3-28 HP 70427A/HP 70428A User's Guide
Enable and
softkey on the
70427A Parms
mm Band Mixer Bias ON/OFF