GAI-Tronics MRTI 2000 (No. PL1877A) Microprocessor Radio Telephone Interconnect Installation & Service Manual - Manual (Page 153)

PL1877A Microprocessor Radio Telephone Interconnect PL1877A – Radio Installation
147 12/10
Earth ground - Run the supplied #12 black ground wire from the PL1877A GND terminal to the base
station chassis. This wire must be as short as practical, not coiled, and connected securely to the base
station chassis.
If this is a control station in a repeater system that transmits PL/DPL during transmit turn-off delay, it is
necessary that the repeater be set for zero turn-off delay. (See Note 2).
Required Parameters – Using the Parameter Modification Procedure, set the following parameters:
Parameter Setting
1 0 (de-emphasis)
2 1, JU202 OUT (low-level source)
3 0 (internal carrier detect)
4 Don’t care
5 0 (internal squelch for carrier detect)
6 0 (No PL detect input required)
1 (PL detect input required)
7 1 (PL detect input is active high)
If parameter 6 =0, parameter 7 = don’t care.
9 1 (simplex)
10 0 (active low PTT sense input
70 0 (signal search)
1 (enhanced VOX, requires the enhanced VOX option)
All other parameters are programmed as applicable to system requirements. Refer to the Parameter
Modification Procedure starting on page 77 and then the Level Setting section on page 17 of this manual.
N OTES :
1. MAXAR Quadrature Detector Adjustment can cause receiver response time problems, especially in
DPL systems. This can adversely affect PL1877A operation, especially in the signal search mode.
The following procedure ensures the shortest possible receiver PL/DPL response time and is the
procedure currently being used on all MAXAR, MOXY and MAXAR 80 radios being shipped form
the factory.
a. Transmit into a 50-ohm load at 13.8 V.
b. Note meter 2 (quadrature output) using a high impedance DVM (may be necessary to measure on
the radio circuit board if the meter 2-wire was used in the PL1877A installation).
c. Dekey the radio.
d. Inject a 10.7 MHz signal into the I.F. of the MAXAR radio.
e. Adjust the quadrature coil (L18 or L23) for a meter 2 reading as measured in step “b”, ±0.1 V dc.
This procedure reduces or eliminates the pulse to the PL/DPL deck caused by the difference of
quadrature voltage between transmitting and receiving an on-frequency signal. Note that a mobile
transmitting off-frequency can cause the same problem.