56
6...There is also room in Roger’s box, to fit one of the suggested Maplin or CPC relay ‘cards’. These are usually negative voltage
triggered and their input pin just connects to pin 8 of the radio power plug. They come equipped with suitable relays usually and
would make the job easier. Fitting a long-period timer at this point would allow the rebroadcast to switch itself off after a pre-set
period of time. If this is used, it could be re-activated using a selcall sequence that just needs to provide a trigger pulse to the
timer input line.
7...CTCSS or ‘tone-mute’ is permitted on the rebroadcast channel of 147.350 MHz only. A single tone of 218.1 Hz is also allowed
on the Team Working Channels (TWC). There are conditions under which we might need to use CTCSS but they haven’t yet
occurred.
8...In the TMC ’Standard repeater’, the original RJ45 socket where the control head is normally connected, is not used when a
DMAP board is fitted. As the radio can’t be programmed via the DMAP sockets but they can do everything else we require, leaving
the original socket empty allows it to be used for programming the radio without first having to unplug something else. Unfortu-
nately this doesn’t work with modified rebros as the original RJ45 sockets are the ones we need.
9...Don’t forget to program your ‘Minimum Speech’ setting to 15 on all radios used in any of the rebro systems or
you will get weak or no audio from the rebroadcast transmitters.
10...If programming radios for rebroadcast, please remember that the Team Working Channels are programmed at a channel
spacing of 25 KHz whereas the Rebro channel 147.350 MHz is spaced at 12.5 KHz.
IN4001 Diode
+
Relay
Coil
Vehicle Positive Supply
Protection Diode when a relay is used.
Switched supply to the secondary radio
Negative supply via pin 8 on the power connector
+
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