User's Manual

Repeater Installation
2-7
2-8 ISOLATION AND ALIGNMENT PROCEDURES
After completing the installation, turn-on procedure, and setup you must align and verify proper
operation of the R19XX.
Note: Watkins-Johnson repeaters incorporate an over power protection algorithm. This algorithm
detects when the repeater is transmitting at a power level above that allowed by the FCC. The
repeater continuously reduces the gain of the repeater until the output power is reduced to an
acceptable power level. An Osc/Max Pwr alarm is generated when this occurs.
2.8.1 ISOLATION PROCEDURE
Performing the isolation test will ensure proper system operation. If the Donor and Server
antennas are not sufficiently isolated, the repeater will oscillate and MAY turn off, causing
dropped calls and coverage holes.
a. Set Uplink and Downlink Gain settings to minimum. Turn off Downlink ALC and
Uplink Tracking.
b. Set Donor Channel # to unused channel(s) with no signal activity. Note: This is not
possible with full-band filters
c. Increase Downlink gain setting by 2dB. RSS should read minimum.
d. Increase Uplink gain by 2dB. RSS should still read minimum.
e. Repeat steps C and D until the maximum gain settings are reached. If there is any signal
present at RSS or the OSC alarm turns red, there is not enough isolation between
antennas, and you must increase the physical distance between antennas or change the
Server antenna direction away from the Donor antenna.
f. Typical industry practice is to allow a 14dB margin between the gain setting and the
oscillation point, but this is at the user’s discretion.
g. As an alternative to steps a through f, set gains to desired levels and click the “OSC
Test” button in the Repeater Control software. The repeater will automatically add
14dB to the Uplink and Downlink gain settings, and “Oscillation Test Active” will
appear in the lower left-hand corner of the Repeater Control window.
h. After the message, “Oscillation Test Active” returns to “Device Online,” verify no
Alarms are illuminated red. If no alarms are red, the test is complete. If alarms are
illuminated red, go to step i.
i. Reposition to Donor and/or Server antennas to improve isolation or lower Uplink and/or
Downlink gain settings by 2dB, clear alarms, and return to step h.