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Notes and things to be aware of:-
1...The alternative front panel supplied with the DMAP board and carrying the 25 pin ‘D’ connector, does not need to be fitted if
the facilities available on the 25-pin connector are not going to be used. Don’t fit the ribbon connection to the DMAP board and
use the existing front panel by knocking out the pre-cut covers over the RJ45 connections. This takes up less space when you’re
trying to sort all the connections out inside your vehicle. It also makes re-assembling the radio a lot easier as you don’t now have
to stuff the 25 way ribbon cable inside.
2...The DMAP board can be fitted with a GPS receiver for those wishing to experiment with automatic vehicle location (AVL). No
additional programming is necessary. The MA-ASIG board can also take a GPS and then becomes known as MA-ASIGF. Unfortu-
nately the control head and the GPS both need the same serial port and the board only has one. However, if anyone intends to
build up a GPS receiving system in their base then an MA-ASIG board without GPS will provide the necessary connection to the
computer. DMAP boards are about four times the cost of an MA-ASIG board. An MA-ASIGF board can also be fitted to a vehicle to
allow GPS tracking with a standard control head fitted.
3...If you are doing any modifications to the box containing the diplexer and aerial change-over relay, note that Roger Taylor who
built them, fitted a drilled, Perspex spacer under the relay. This is because the screws used are slightly too long and without the
spacer, will pass through the mounting plate and straight into the coil winding of the relay. Very bad.
4...If anyone wants to fit the suggested power relay to provide controlled switching of the secondary radio, Alan Prescott at Kes-
wick fitted a small one inside the power plug shell, extremely elegant. You can also fit a larger one into the existing diplexer case
alongside the aerial relay.
5...If the suggested circuit for the modified ‘Standard’ repeater is used, remember that a transistor switch has already been fitted
to the aerial relay. In this configuration, it’s not necessary and can be removed with care. The pins it’s connected to are the ones
you connect to the power plug pins 4 and 8. The relay should be fitted with a back-EMF prevention diode wired as shown in the
diagram following. This stops the voltage generated by the collapsing magnetic field, when the relay is switched off, from blitzing
your radio's sensitive parts. If you use a dash-mounted switch to provide power, you don’t need the diode.
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