User's Manual

Maintenance Handbook
Baltimore Radio Repeater System
Handbook No. 60-166501HBKM Page 21 of 26
5.8 Care of Modules
Many of the active modules contain semiconductor devices utilising MOS technology, which can be
damaged by electrostatic discharge. Correct handling of such modules is mandatory to ensure their
long-term reliability. Good engineering practices should be observed at all times.
To prevent damage to a module, it must be withdrawn/inserted with care.
5.9 Module Removal (LNAs, general procedure):
The following general rules should be followed to remove a module:
1) Remove power to the unit
2) Remove all connectors (RF, DC/alarm)
3) Release module retaining screws.
4) Slowly but firmly, pull the module straight out of its position. Take care not to twist/turn the
module during withdrawal.
5.10 Module Replacement (general):
1) Carefully align the module into its location then slowly push the module directly straight into its
position, taking care not to twist/turn it during insertion.
2) Reconnect all connectors, RF, alarm, power etc.
3) Replace retaining screws (if any).
4) Double-check all connections before applying power.
5.11 Power Amplifiers
1) Remove power to the unit. (Switch off at mains/battery)
2) Disconnect multi-way alarm ‘D’ type connector
3) Carefully disconnect the RF input and output coaxial connectors (usually SMA)
4) If the amplifier to be removed has a heatsink attached, there may be several different ways it
can have been assembled. The most commonly used method, is screws through the front of the
heatsink to threaded screw holes (or nuts and bolts), into the amplifier within the main case. If the
heatsink is mounted on the rear of the main case (e.g., against a wall in the case of wall mounted
enclosures), then the fixing method for the heatsink will be from within the case, (otherwise the
enclosure would have to be removed from the wall in order to remove the heatsink).
When the heatsink has been removed, the amplifier may be unscrewed from the main casing by its
four corner fixings and gently withdrawn.
Fitting a new power amplifier module will be the exact reverse of the above.
Note: Do not forget to apply fresh heatsink compound to the heatsink/main case joint and also
between the amplifier and the main case.