User's Manual

VHF Headstation & In-Line Amplifiers
User Handbook
Handbook Nō.-50-127201FCC Issue No:-A
Date:-14/06/2005
Page:-
22 of 45
4. SUB-UNIT MODULES
4.1 Bandpass Filter (01-002503)
4.1.1 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 helical 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 50Ω 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.
4.1.2 Technical Specification
SPECIFICATION PARAMETER
Response type: Chebyshev
Frequency range: 135 – 250MHz
Bandwidth: 3.5MHz (tuned to spec.)
Nō. of sections: 6
Insertion loss: 1.2dB
VSWR: Better than 1.2:1
Connectors: SMA
Power Handling: 100W maximum
operate: -10°C to +60°C
Temperature range:
store: -20°C to +70°C
Weight: 3 kg
Size: 384 x 82.5 x 56.4mm