User's Manual

P B L Tunnel Units 1 & 2
Maintenance Handbook
H/book Number:-60-056100HBKMFCC
Issue No:-2
Date:-04/01/2006
Page:-
25 of 63
5.2
Unit 2 (60-056102)
5.2.1 Bandpass Filter (02-013401)
5.2.1.1 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.
5.2.1.2 Technical Specification
PARAMETER SPECIFICATION
FILTER 1 470-470.5MHz Passband:
FILTER 2 473-473.5MHz
FILTER 1 2.8 dB typical
Insertion Loss:
FILTER 2 2.8 dB typical
FILTER 1 470-470.5MHz > 60 dB
Rejection:
FILTER 2 473-473.5MHz > 60 dB
Power Rating 250 Watt
Impedance 50 ohm
VSWR Better than 1.2:1
Connectors SMA female