User's Manual

Bronx Justice Centre Radio Repeaters
Handbook Number: 80-283501HBKM Page: 25 of 86
4.1.9.1Description
The simplex channel amplifier shelves (x3) receive their input signals from antennas and are
processed as follows:-
The Simplex controller module (17-015301) monitors the receiver output for a signal change and
activates the supply switching for either the uplink or down link path accordingly. In normal operation,
the low level Rx path is activated and the associated Tx path is switched off. When a signal is
detected by the downlink channel selective module, the Rx output goes low, which triggers the
controller logic PCB. The PCB mutes the power supply to the opposite path Rx LNA’s and switches
on the power to the output power stage. In order to prevent the power stage noise blocking the
opposite path’s low level receiver, the power amplifier is normally muted.
Both outputs are protected by ferrite isolators in a similar way to the duplex shelves.
All three simplex shelves are hardware similar so only channel 3A shelf is described.
4.1.9.2Technical Specification
PARAMETER SPECIFICATION
Height: 3U
Width: 19" (482.6mm)
Shelf
dimensions:
Depth: <450mm (excluding connectors & handles)
operational: -20°C to +60°C Temperature
range:
storage: -40°C to +70°C
Weight: <10kg
154.785MHz (Ch. 3A)
154.755MHz (Ch. 3B)
Channel frequencies:
154.980MHz (Ch. 4)
Shelf gain: 100dB (typical)
Impedance: 50ȍ
Humidity: 5 – 95% non-condensing
RF Connectors: N type female
Environmental protection: IP44
Case: Iridite NCP coating
Heatsinks: Black anodised
Handles: Silver anodised aluminium alloy
Finish
Fascia: Painted to RAL7035