MTR3000 Radio Frequency Distribution System (RFDS) Equipment: Field Tuning Procedures 9-27
Figure 9-21 Inspect against mask template
b. Tighten the tuning nuts to approximately 1.36 Nm (12 in-lbs), so the screws are secure.
Make very slight adjustments at any of the screws to compensate for change tightening
that screw causes.
4. Reassembly
a. Mount the preselector assembly in the Station, and reconnect the previously-removed
cabling.
Note
• All instruments should be properly calibrated before operation.
• All joints between cavity and instrument should be checked. Loose connections can
greatly impact the tuning results.
• Rejection meets specification requirements after passband and return loss are tuned,
and it is needless to check one by one. However, the passband shall be tuned to the center
frequency. In other words, insertion loss of two side frequencies of passband is
approximate.
• Lock the tension nut with proper torque force: 1.2 Nm~1.3 Nm. Excessive torque will lead
to excessively tight locking (hard to tune) and inadequate to loose locking (tuning screw
falling off)
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