User Manual

UHF Bandselective BDA
90dB 40/5W
Document Number 55-199102HBKM Issue No. 1 Page 21 of 28
6.3. Quick Fault Checklist
All AFL equipment is individually tested to specification prior to despatch. Failure of this type of
equipment is not common. Experience has shown that a large number of fault conditions relating to
installations result from simple causes often occurring as result of transportation, unpacking and
installation. Below are listed some common problems which have resulted in poor performance or an
indicated non-functioning of the equipment.
Mains power not connected or not switched on.
External connectors not fitted or incorrectly fitted.
Internal connectors/ports becoming loose due to transport vibration.
Wiring becoming detached as a result of heavy handling.
Input signals not present due to faults in the aerial or feeder system.
Base transmissions not present due to faults at the base station.
Modems fitted with incorrect software configuration/and or PIN Nos.
Changes to channel frequencies and inhibiting channels.
Hand held radio equipment not correctly set to repeater channels.
Hand held radio equipment not correctly configured to base station.
6.4. Downlink
C
onfirm that there is a signal at the expected frequency and strength from the base station(s). If this is
not present then the fault may lay outside the system. To confirm this, inject a downlink frequency
signal from a known source at the BTS input and check for output at the antenna output port.
If a signal is not received at the output it will be necessary to follow the downlink path through the
system to find a point at which the signal is lost.
6.5. Uplink
T
esting etc. of the uplink paths is similar to the downlink paths, except for the frequencies involved.
6.6. Fault repair
O
nce a faulty component has been identified, a decision must be made on the appropriate course to
carry out a repair. A competent engineer can quickly remedy typical faults such as faulty connections
or cables. The exceptions to this are cable assemblies connecting bandpass filter assemblies
(duplexers) that are manufactured to critical lengths to maintain a 50-ohm system.
Care should be taken when replacing cables or connectors to ensure that items are of the correct
specification. The repair of component modules such as amplifiers and bandpass filters will not
usually be possible in the field, as they frequently require specialist knowledge and test equipment to
ensure correct operation. It is recommended that items of this type are replaced with a spare unit and
the faulty unit returned to AFL for repair.
Following the repair of any part of the system it is recommended that a full end-to-end test is carried
out in accordance with the test specification and that the coverage is checked by survey.
It is important to bear in mind that the system includes antennas and base stations that m
ay be faulty
or may have been damaged.
6.7. Service Support
A
dvice and assistance with maintaining and servicing this system are available by contacting Aerial
Facilities Ltd. see section 2.7.