Product manual

Hardware Jumper Settings
21
JP6 (MODEL 26 CHAIN TERMINATION)
JP6 selects the termination resistance for the “CHAIN” interfaces. The “CHAIN”
interface is used to link together multiple dispatch positions. There are three positions for
this jumper:
Position A = Unterminated CHAIN Interface
Position B = Terminated CHAIN Interface
No jumper = Same as the Unterminated position
All positions except one should be unterminated (A). Usually the primary position is
terminated (B) and all of the secondary units are unterminated (A).
JP7 (MICROPROCESSOR MODE SELECT)
This jumper should never be installed. It is for factory use only.
JP8 (COR INPUT POLARITY)
JP8 selects whether or not the RX COR input (J13-5) is pulled-up or pulled-down
through a 10kΩ resistor, or is floating. There are three positions for this jumper:
Position A = Selects a floating input
Position B = Sets input to be pulled-up to 12 Vdc
Position C = Sets input to be pulled down to ground
If the Model 26 is connected to a radio that provides a COR output signal via a contact
closure, then JP8 should be in position B. If the COR signal is a voltage source, this
jumper should be in the A position (floating).
If the Model 26 is connected to a radio with no COR output or is connected to a wire line,
then the VOX circuit should be used to detect channel availability. In either case, JP8
must be in the B position (pulled-up) to prevent the RX COR input from interfering with
the VOX signal (refer to the JP3 description).
If the Model 26 is connected to a trunked radio system, the RX COR input is needed for a
grant signal from the radio. If the grant signal is active low, then JP8 should be in the B
position (pulled-up). If the grant signal is active bi-polar (e.g. ±10V), then this jumper
should be in the A position (floating).