Technical Manual

11-75-0000 SYNTHESIZED PAGING TRANSMITTER TECHNICAL MANUAL Issue 0600
Sea Air and Land Communications Ltd Page 5
4.0 MECHANICAL DESCRIPTION
The 1175 is enclosed in a pressed aluminium box.
The lid will unclip to reveal 16 screw terminals, and adjustment for the low supply detector. The lid can also be used for mounting the unit on a wall, and the overhang
can be cut or modified to allow cable entry as required. It is advisable to mount the unit away from sources of heat, damp or vibration.
5.0 INSTALLATION
The power supply should be connected as illustrated on page 5, at a voltage shown in the specification. The supply input is protected against reversed connection. The
aerial connection is via the BNC connector, and should present a nominal load of 50
Ω
, with a VSWR of better than 1.8:1. It is recommended to site the aerial a few
metres away from the 1175 to avoid RF feedback causing problems with the transmitter operation. An outside aerial is preferable, as it will provide better radio
coverage.
External indicators consist of a power indicator GREEN LED, normally ON with very brief flashes to indicate healthy micro-controller operation. After a de-bounce
period, the green LED will flash rapidly if the low supply detector is activated.
The RED LED will indicate when the unit is transmitting. A flashing RED LED indicates the unit cannot transmit as either the synthesiser is out of lock or the
channel
busy
input is active.