User Manual

5-Way Channelised UHF Cell Enhancer
Maintenance Handbook
H/book Number:-50-060601HBKM
Issue No:-
1
Date:-04/07/2003
Page:-
19 of 54
5. SUB-UNIT MODULES
5.1 Downlink Channelised Cell Enhancer 60-060602 (5U chassis)
5.1.1 Bandpass Filters (02-010701)
5.1.1.1 Description
The bandpass filters are multi-section designs with a bandwidth dependent upon the
passband frequencies, (both tuned to customer requirements). The response shape is
basically Chebyshev with a passband design ripple of 0.1dB. The filters are of combline
design, and are carefully aligned during manufacture in order to optimise the insertion loss,
VSWR and intermodulation characteristics of the unit. The tuned elements are silver-plated
to reduce surface ohmic losses and maintain a good VSWR figure and 50 load at the input
and output ports.
Being passive devices, the bandpass filters should have an extremely long operational life
and require no maintenance. Should a filter be suspect, it is usually most time efficient to
replace the module rather than attempt repair or re-tuning.
No adjustments should be attempted without full network sweep analysis facilities to
monitor both insertion loss and VSWR simultaneously.
5.1.1.2 Technical Specification
PARAMETER SPECIFICATION
Passband 453-454 MHz
Insertion Loss 1.9 dB typical
> 456 MHz > 55 dB
Rejection
> 458-459 MHz > 60 dB
Power Rating 50 Watt
Impedance 50 ohm
VSWR Better than 1.2:1