Table of Contents
Procedure 2
Initial Setup
Checking the Reference
LO Power
NOTE
Installation
Adjustment Procedures
This procedure applies to systems that use HP 85320A/B mixers, in addition
to the HP 85325A.
1. Refer to the detector voltage label on the HP 85320B reference mixer.
Set the HP 85309A "LO POWER ADJUST" control to match this value.
You do not need to connect the HP 85320B mixer to the system.
2. Zero and calibrate the power meter.
3. Determine the power sensor calibration factor at 4 GHz, and set the
power meter accordingly.
4. Connect the power sensor to the LO output of the HP 85326A reference
module (refer to Figure 1-4 on page 1-11). Be sure to connect the power
sensor to the end of the LO cable.
1. Measure the power output of the reference module.
a. If measured power is between 15 and 17.5 dBm, no adjustment is
necessary. Go directly to the Adjusting LO Power to the Test Mixer
section on page 1-15.
b. If the measured level is outside of the above range, you will have to
change the LO power whenever you switch between HP 85320A/B
and HP 85325A mixer systems. For HP 85320A/B mixers, refer to
the HP 85320A/B Mixer Modules User's Guide
Since you must set the LO power separately for each type of mixer,
adjust the LO power for the millimeter-wave mixers at this time. To do
this, perform Procedure 1, starting at "Adjusting LO Power to the
Reference Mixer." on page 1-12.
2. Adjust the HP 85309A front panel LO POWER ADJUST control until
the power meter reads between 17 and 17.8 dBm. The "LO POWER
OUT OF RANGE" light should be off.
3. Note the reading of the HP 85309A display and write it down here:
HP 85326/85320 DETECTOR VOLTAGE SETTING: ________ millivolts.
If the LO POWER ADJUST setting is ever changed, you can return to the
appropriate power level for the millimeter system by referring to this setting.
To return to the original power level, Turn the LO POWER ADJUST knob
until the voltage reading matches the value written above.
When performing the following step, connect the LO, IF, and detector
voltage cables to the reference module first, then connect cables to the mixer.
This lowers the risk of electrostatic damage to the mixers.
1-14 HP 85325A Operating and Service Manual
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