User's Manual

Weehawken Tunnel UHF Repeaters
User/Maintenance Handbook
Handbook N.-Weehawken_UHF Issue No:-A
Date:-05/08/05
Page:-
44 of 72
7. SUB-UNIT MODULES
Note that the sub unit modules are tabled in part number order – the modules pertinent to any
particular shelf will be found in the parts list under the heading of that shelf.
7.1 Bandpass Filter (02-013401)
7.1.1 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.
7.1.2 Technical Specification
PARAMETER SPECIFICATION
FILTER 1 483.2-483.6MHz
Passband:
FILTER 2 486.2-486.6MHz
FILTER 1 2.7 dB (typical)
Insertion Loss:
FILTER 2 2.7 dB (typical)
FILTER 1 483.2-483.6MHz > 80 dB
Rejection:
FILTER 2 486.2-486.6MHz > 80 dB
Power Rating: 250Watts
Impedance: 50 ohm
VSWR: Better than 1.2:1
Connectors: SMA female