Mod for PRO 2042 (Trunking).


The mod described here is intended for educational use. It was done on
a PRO 2042 with an Optoelectronics OS 535 board (export) fitted, but
may well work on the PRO 2035 although I have not tried it. First of
all this method requires two scanners and a computer in order to trunk
track. You will also need a program called Trunker.exe. Trunker.exe is
a dos program and can be obtained from the internet. The second scanner
must be capable of tuning into and receiving the trunking data signal.
It will also need its discriminator to be tapped and terminated with a
mono jack plug.

Basically all you need do is fit a mono earphone socket in line with
the orange wire which is solderd to TP2 on the main circuit board of
the PRO2042 and which then goes to the OS 535 board. All you then need
do is inject the discriminator output from your second scanner into
the  OS 535 by using the mono earphone socket that you fitted. The mono
socket is best fitted to the metal chassis at the rear of the radio so
that it is grounded or it may not work. TP2 provides a test point for
the Pro 2042 discriminator audio. You could simply cut the orange wire
at a suitable point, but I found that there wasnt enough of the orange
wire to reach from TP2 to the new mono socket and then back to the OS
535. The best way I found was to strip out the OS 535 board and
unsolder the orange wire from TP2. I Then used a new piece of wire to
connect from TP2 to the mono socket.  This also made it much easier in
locating a suitable position to mount the mono socket and in drilling
the hole. You must take into account when you are choosing a suitable
position for the mono socket that the rear of the mono socket does not
obstruct the refitting of the OS 535 board as the board comes right up
to the rear chassis. You may also find that the new wire coming from
TP2 to the mono socket may pick up some unwanted interferance from the
scanners circuit board or its transformer, you will have to try to
route the wire so that this does not happen. The mono socket acts as a
switch, when there is no jack pluged into the mono socket the 0S 535
board should receive its discriminator signal from TP2 and when the
jack is inserted into the socket the OS 535 board should receive the
discriminator signal from your second scanner. When the OS 535 board is
receiving its discriminator signal from TP2 you will be able to decode
DTMF tones under software control as befor, ie with Scanstar or
Scancat, you will not be able to do this when you have the second
scanner is pluged into the PRO2042. It is important to remember this.
So you will have to make sure that you have unpluged it if you want to
scan for or decode these tones.

What follows is a discription from memory of how I did this mod. No
doubt other people will see other ways of doing it that could prove
easier and be just as successful. The aim of the following is to share
information. You should also be aware that if your scanner(s) and 0S
535 are damaged when doing this mod your warranty with the
manufacturers/suppliers will be void. I take no responsibillity for any
damage caused or any incorrect information.

Make sure you disconect the scanner from the mains before you start to
take it apart. This may sound like a naff suggestion, but shit happens
and there aint no point in killing yourself. You will need to remove
the covers by unscrewing the four screws at the back end of the radio.
Seperating the covers from the radio can prove to be difficult because
they are a tight fit, but basically they sould slide back and seperate.
The top cover contains the speaker which can be unpluged from the
radios main circuit board after you have removed the OS 535 board from
the scanner. Removing the OS535 board is quite simple. If you do not
have the fitting instructions then its a good idea to make a note of
where the verious plugs plug into. All of the sockets are labelled.
Remove the OS535 board by unscrewing the six or so screws holding it in
place, also the two small screws with the two nut's and two washer's
which hold the labelled plate in place at the rear of the scanner. The
orange wire that comes from the 0S 535 and goes to TP2 needs to be
unsolderd at TP2 on the scanners main circuit board. You might get away
without having to unsolder the thin blue wire if you can move the board
out of the way far enough so that it does not interfere with what you
are doing. If you do decide to leave it in place then make a note of
where it attatches to on both the OS 535 board and the radios main
board as it may become dettatched later by accident. You now need to
fit a mono earphone socket to the rear of the scanner. With the scanner
the right way up and looking at the back I fitted mine about 1 inch
above and slightly to the right of the arials BNC connector. You have
to be careful here, if you look on the inside of the scanner two pieces
of the chassis join together and overlap about here. You will need to
drill a hole in the metal chassis, avoiding the over lap. This is
because if you hit the overlap then the socket that you are fitting may
not sit straight.  Choose a place so that when you fit the socket the
OS 535 board will not be obstructed by the socket as the back edge of
the board sits very close to the chassis. When you drill the hole do
not let any of the metal fall into the scanner as this could cause the
scanner to short out. It's best to do the drilling with the scanner
turned upside down so that the metal will fall out of the scanner and
away from the circuit board. After you have drilled the hole you will
need to file away the burrs made by the drilling on the inside and the
outside of the chassis again being careful not to let any metal filings
fall into the scanner. After you have done this it is a good idea to
check thoroughly for any metal filings that did make it to the scanners
circuit board and to remove them. Fit the socket in the hole and secure
it temporarily. Check that the socket does not obstruct the OS 535
board by placing the OS 535 board back into the scanner making sure
that you can secure it back into position. When you are satisfied that
this can be done remove the OS 535 board. The mono socket should have
three solder tags. You will have to identify which solder tags the
wires in the next part are to be attatched to. You now need to solder a
new wire to TP2 and to the solder tag of the mono socket that will
disconnect  the OS 535 when the mono jack is pluged in. Remember that
you may have to adjust the route of this wire as it may pick up
interferance from the scanners circuit board, it is best to make this
wire as short as possible as this may help to reduce any interferance.
Avoid routing the wire anywhere near to the mains transformer inside
the scanner. The orange wire that you unsolderd from TP2 is now solderd
to the solder tag that will connect to the tip of the jack plug when it
is pluged into the mono socket. You should end up with a switching
action when you plug a mono jack into the socket. With the mono jack
removed, you should have a connection from TP2 along the new wire you
installed  through the mono socket, along the orange wire and into the
OS 535 board. Its path should be free from interferance and
uninterupted. When you plug the the jack into the mono socket, the
connection from TP2 to the solder tag that the orange wire is soldered
to should cease. The discriminator signal from the first scanner should
appear at the tip pin of the mono jack which will connect to the tag
that the orange wire is soldered to. Make sure that the mono socket is
grounded to the scanners chassis. When you are satisfied that the
wiring is correct reconnect the speaker then refit the OS 535 and
reassemble the scanner.

You should have a copy of trunker.exe on your computer. To set the
program up you will need to edit the Trkenv.txt file to the following.

TRACKSLICERPIN = DSR
TRACKSLICERPORT = COM2
TRACKSLICERMODE = NORMAL
TRACKSCAN = OPTO
TRACKSCAN = 9600
TRACKSCANPORT = COM2
TRACKSCANPARK = 450.0000 (You may need to use a different frequency if
this one is in use where you are located. See the Trunker documentation
for an explanation of this setting).

NONEMERGENCY = OFF

If you use this configuration you will need to connect your PRO 2042 to
comport 2. No other comport connections will be necassary.


All the best, Midnight.