User Manual

STTRS DOCUMENTATION
Document Number 80-330501HBKM – Issue A - Draft Page 395 of 500
21.3.1.10. 24V Relay Board (80-008902)
The General Purpose Relay Board allows the inversion of signals and the isolation of circuits. It is
equipped with a single, dual pole, change-over relay RL1 with completely isolated wiring, accessed
via screw terminals.
The relay is provided with a polarity protection diode and diodes for suppressing the transients
caused by "flywheel effect" which can destroy switching transistors or induce spikes on neighbouring
circuits. It’s common use is to amalgamate all the alarm signals into one, volts-free relay contact pair
for the main alarm system.
80-008902 Technical Specification
Parameter Specification
Max. switch current 1.0Amp
Max. switch volts 120Vdc/60VA
Max. switch power 24W/60VA
Min. switch load 10.0µA/10.0mV
Relay isolation 1.5kV
Mechanical life >2x10
7
operations
Relay approval BT type 56
Connector details 15-way 0.1" pitch
operational -10°C to +55°C Temperature
range
storage -40°C to +70°C
21.3.1.11. Dual Isolator (770MHz) (93-910048)
The purpose of fitting an isolator to the output of a transmitter in a multi-transmitter environment is so
that each output is afforded a degree of isolation from every other. Without the addition of Isolators,
simultaneous transmissions could interfere to create intermodulation products and spurious
transmissions would be created which would cause interference.
Dual Isolator (93-910048) is a ferro-magnetic RF device, which has directional properties. In the
forward direction, RF arriving at the input is passed to the output with minimal attenuation. In the
reverse direction, RF arriving at the output due to reflected power from a badly matched load, or due
to coupling with another transmitter, is routed into an RF load where it is absorbed. The isolator
therefore functions to prevent reflected RF energy reaching the output port of an amplifier where it
could cause intermodulation products or premature device failure.
Dual Isolator (93-910048) is as its name suggests a two stage device, essentially two isolators in one
casing. One isolator stage has an internal 10W load fitted, the second stage needs an external load
fitted of sufficient rating to absorb the reflected power levels that can be reasonably expected within
the system. In this instance Dual Isolator (93-910048) is fitted with external load 09-000902.
93-910048 Specification
Parameter Specification
Frequency Range 760-780 MHz
Insertion Loss 0.4 dB max.
Isolation 50 dB min.
Return Loss 23 dB min.
Power Handling 10W (internally fitted load)
RF Connectors N female