Interfacing external repeater controllers to the Motorola MSF5000 repeater.


The MSF5000 CLB series Analog stations require a 2736A EPROM chip to be burned. The key to making this all work is in the programming.

There are several articles on interfacing controllers to the MSF5000, and several of those articles state they use external PL decoders because
no one can figure out how to get the station to decode and encode PL.  I did! (I work on these stations professionally for the bat wings (/\/\)

I'm not going to bore you with why this and how much that and use this formula combined with that test to produce whatever.. 

Here's what really works:

Program your chip, or have it programmed with your TX and RX frequencies, and whatever PL tone you wish decoded (received by the station)
and whatever PL tone you wish encoded (transmitted by the station). Do not enter a call sign! Set the Priority to LWR. Set the Receiver Squelch
to "C," set the Repeater Squelch to "SC" set the Hold In to "C," and set the Repeat In Box to NO.  Burn the chip and place it into the station.
Perform the regular station alignment at this point.

Repeater Controllers and Tone Panels require basic input and output signals. You need a Ground (GND), Transmit PTT (PTT), Received Audio
(RX IN), Audio Out to be Transmitted (TX OUT), a signal to show Squelch opening (COR), and a signal to show PL decoding (CTCSS).

Flip up the MSF5000's control deck and you can obtain all the signals from the following locations:

GND - J800, pin 10 (not always required if powering from the station's DC supply)
RX IN - J800 pin 39
TX OUT - Pin 13 of U834 via a 20K ohm 1/4 watt resistor
CTCSS - Pin 14 of U829

On a more technical note, PTT occurs when TP9 is grounded. RX IN is strong at J800 pin 39, you may need to attenuate it with a resistor.
TX OUT is amplified here so I have found a 20K ohm resistor delivers great audio and your controller's output pot should adjust this nicely.
COR at TP7 goes high, about 4 volts. All the controllers I deal with or have built have selectable, logic hi or low, set it accordingly for hi.
CTCSS at pin 14 of U829 goes hi, about 3.5 volts and only goes hi when PL is received by the station with the above programming!  This
works perfectly well. As with COR, set it to logic hi when PL is decoded.


Here is the wired control tray, ready to go back on the station.

PTT is accomplished by pulling TP9 (test point 9) to ground.

RX IN - Audio received by the station. J800, pin 39.

TX OUT - Audio to be transmitted by the station. Solder a 20K ohm resistor to pin 13 of U834.
              Input the audio from your controller through the resistor at this point.

COR - Use TP7 (test point 7) for your COR detect. This point goes high when the station is receiving.
         (around 4 volts)

CTCSS - Pin 14 of U829 goes hi when the station is receiving the programmed PL or DPL tone.
            (around 3.5 volts)

For the installation pictured above, I used CAT5 cable and wound the leftover wires back around the wires to
hold everything neat and snug.  I drilled a hole in the back wall of the plastic tray to pass the cable through.

For this particular build, I mounted the controller in an MSF5000 expansion tray and fitted it to the top of the
control deck shown above.  The cable is simply routed into the expansion tray and connected to the controller.
This makes for a very neat and professional installation and there are no loose wires or harnesses to pull loose.

I hope this helps, and shows you how you really can get an MSF5000 to decode PL / DPL in the cabinet with
the wiring and programming depicted above.


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