User Manual

Axell Wireless Limited
Technical Literature
FM Rebroadcast Amplifier 55-203201
Document Number 55-203201HBK Issue No. 1 Date 22/12/2008 Page 16 of 23
5.3.4. Power Amplifier Replacement (general procedure)
1) Remove power to the unit. (Switch off at mains/battery, or remove DC in connector)
2) Remove alarm wires from alarm screw terminal block or disconnect multi-way alarm
connector.
3) Carefully disconnect the RF input and output coaxial connectors (usually SMA)
If alarm board removal is not required, go to step 5.
4) There is (usually) a plate attached to the alarm board which fixes it to the amplifier, remove
its retaining screws and the alarm board can be withdrawn from the amplifier in its entirety.
On certain types of amplifier the alarm board is not
mounted on a dedicated mounting plate;
in this case it will have to firstly be removed by unscrewing it from the mounting pillars, in
most cases, the pillars will not have to be removed before lifting the amplifier.
5) 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four corner fixings and gently withdrawn.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.
5.3.5. Low Power Amplifier Replacement (general procedure)
• Disconnect the mains power supply and disconnect the 24V dc supply connector for the
LPA.
• Disconnect the RF input and output cables from the LPA.
• Disconnect the alarm connector.
• Remove the alarm monitoring wires from (D type connector) pins 9 and 10.
• Remove the LPA module by removing the four retaining screws, replace with a new LPA
module and secure it with the screws.
• Connect the RF cables to the LPA input and output connectors. Reconnect the wires to the
alarm board connector pins 9 and 10.
• Reconnect the DC supply connector and turn the mains switch on.
Note: Tighten SMA connectors using only a dedicated SMA torque spanner. If SMA connectors
are over-tightened, irreparable damage will occur. Do not use adjustable pliers to loosen/tighten
SMA connectors.
Also take care not to drop or knock the module as this can damage (or misalign in the case of
tuned passive modules) sensitive internal components. Always store the modules in an
environmentally friendly location