GAI-Tronics MRTI 2000 (No. PL1877A) Microprocessor Radio Telephone Interconnect Installation & Service Manual - Manual (Page 151)

PL1877A Microprocessor Radio Telephone Interconnect PL1877A – Radio Installation
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3. 60-Second Mobile Inactivity Timer:
In the enhanced VOX simplex mode, the land-line caller cannot be interrupted by the mobile (until
the 30-second time-out). Therefore, it is possible for the mobile to hear the warning ticks and not be
able to reset the inactivity timer because the land-line party is talking. Therefore, it is recommended
that the mobile inactivity timer (parameter 122) be set to 3 minutes of mobile inactivity in Enhanced
VOX simplex systems.
Intercabling Diagram – Maxar/Moxy Control Station to PL1877A
MAXAR 80 Bases
MAXAR 80 Bases are characterized by two large power pins in the cable connector, pins A and B.
Install the following modifications/additions to the base station using the supplied female pins where
necessary.
1. RX Detector Audio - Run a wire from U10, pin 6 to J601-6 (wire for meter 2 may be in pin 13 of
J601 and possibly could be rerouted and used for this function).
2. TX PL Disable - Run a wire from the PL/DPL code disable - pin CD or TD o the PL/DPL deck to
J601-3.
3. PL Detect
Tone PL (reed type, TRN6177C and similar) Locate and remove the soldered-in JU401 and install
a 100k, ¼ W resistor in its place (Note: There are two JU401’s shown on the board pictorial. The
correct one for this function is the one is series between U401, pin 13 and Q409 base. This resistor
allows pin 13 of U401 to swing between detectable logic levels). Remove C428 and replace it with a
1
µF capacitor, observing polarity. Run a wire form U401, pin 13 to J601, pin 4.
Tone PL (reedless type, TRN6207A and similar) Run a wire from U401, pin 28, on the PL deck to
J601, pin 4.
Digital PL (TRN6207A and similar) Run a wire from U301, pin 7, on the DPL deck to J601, pin 4.