Cavity Combiner - Fru Replacement Process - Motorola DIMETRA MTS 2 Installation, Configuration And Basic Service Manual

Cavity Combiner - FRU Replacement Process

If the TX carrier does not change channel or average power level, the auto tune algorithm will not initiate a
re-tuning on its own which exceeds +/- 300 kHz from the carrier frequency. The only exception occurs when
the fine tune timer event happens. The fine tune timer is used to compensate for large variations in humidity
and is default set to 480 Minutes. The Cavity Combiner is temperature compensated but large variations in
humidity can de-tune the cavities up to 150 kHz with the result of an increasing insertion loss.
When the fine tune timer event occurs, all cavities with RF applied will be re-tuned for maximum output
power of each TX carrier. The fine tune timer can be adjusted to compensate for fast humidity variations;
for instance if the MTS 4 is installed in outdoor sites without air-conditioning. The recommended
setting of the fine tune timer, if the MTS 4 is installed in a controlled environment, is 480 Minutes.
For sites where the MTS 4 is exposed to more than +/- 20% variation in RH, the recommended setting
of the fine tune timer is 60-200 minutes depending on the speed of the variation.
Having a second cavity tune up and pass through the desired channel, the desired channel's insertion
loss dips no more than 3 dB more than the max insertion spec for a period of 0.25 seconds.
The cavity tuning rate should be faster than 1 MHz per second.
The following list contains control and monitoring features available through the CAN Bus:
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Cavity Combiner - FRU Replacement Process
For a list of available FRUs, see
Process 7-7 Replacing the Cavity Combiner
1
2
3
Removing the Cavity Combiner
7-30
Request current tuned position/frequency of a specific cavity.
Fine tune time feature, to re-tune each cavity with a specified interval.
Park an individual cavity, but if RF power is still present, cavity will park and then retune again.
Input power: request current measured input reflected power of a specific cavity.
VSWR: request input VSWR of an individual cavity.
Tuning status of each cavity; parked, tuning, tuned, and parking.
Alarm conditions of each cavity are reported when requested, including : VSWR,
subband, channel spacing and failure to tune.
Appendix A, "Field Replaceable Units
Remove the Cavity Combiner, see
Insert the Cavity Combiner into the cabinet, see
Update the mapping list with the new unit TrackID, see
RF energy hazard and potential equipment damage precaution. Turn off power
to all Base Radios in the equipment cabinet being tuned before performing
the following procedures to prevent serious injury.
Chapter 7: Radio Frequency Distribution System
Procedure 7-16.
Procedure 7-17.
Procedure
(FRUs)".
7-18.
6802800U74-N September 2009