RA-64M Jumper Assignments:

NOTE: Actual usage of the interface determines how many Mini-DIN-6 radio ports are used, 
where the jumpers are positioned, and how many jumpers are actually used. 

NOTE: For a single radio simplex node or digital data communications using SoundModem or VARA FM - 
the simplex node radio connects to only the TX / RX radio port - where all signals pass through 
this port.

NOTE: For building a duplex repeater - both Mini-DIN-6 ports are used. Duplex applications require the 
transmit radio to connect to the TX / RX port, and the receive radio to connect to the RX port on 
the rear of the RA-64M interface.  Duplex operation requires you to use the jumpers to select the 
(correct) receive audio source, COS source and (if necessary) CTCSS logic source from J3 (RX port) 
Mini-DIN-6.  This is explained further below.


Jumper Summary:
JU1 - 1200 / 9600 Baud receiver audio selection for J1 and J3.
JU2 - LEFT or RIGHT TX audio selection.
J1A - COS squelch logic input selection for J1 - TX / RX
J1B - CTCSS squelch logic input selection for J1 - TX / RX
J3A - COS squelch logic input selection for J3 - RX Only
J3B - CTCSS squelch logic input selection for J3 - RX Only
JU4 - PTT LED - false illimination protection selection.
PTT - One of two jumpers to select transistor or relay PTT keying. See NOTE below.
PTT - Two of two jumpers to select transistor or relay PTT keying. See NOTE below.

PTT Source Selection:
The PTT keying method is selectable by two mechanical jumpers. You choose between Transistor or
Relay keying.  The selection between transistor and relay keying is done with a pair of 
two - 2-pin headers in a square arrangement.  These headers are red and require two jumpers 
to be placed in either a up/down or back/forth (vertical or horizontal) side-by-side orientation.
Both jumpers are required for the option to work correctly.  The up/down position selects the 
relay, while the back/forth position selects the transistor.  These headers are located in a 
square box labeled "PTT" near the relay.  If the relay position is selected - it's best to 
also place JU6 - but not required.  In the transistor position - select the position of JU6 
as required and detailed below.
Default is Relay.


JU1 - Receiver audio type / baud rate selection - 1200 or 9600 baud. This dual 4-pin white header 
is beside J1 the TX / RX Mini-DIN-6 radio connector. One jumper selects between pin 5 (1200) or 
pin 4 (9600) from either J1 or J3.  ONLY ONE jumper position is valid - depending on which port 
your receiver is connected to.  
Default is J1 9600.


JU2 - LEFT or RIGHT TX Audio Selection:
JU2 selects between the Left or Right transmit audio channel that reaches the TX / RX Mini-DIN-6 pin 1.
Default is Left.


Squelch Logic Selection:
There are four 2-pin blue headers grouped at the center of the top of the board.  Only one or 
two jumpers being placed is valid - depending on which port your receiver is connected to.
J1A - COS squelch logic input selection for J1 - TX / RX port.
J1B - CTCSS squelch logic input selection for J1 - TX / RX port.

J3A - COS squelch logic input selection for J3 - RX Only port.
J3B - CTCSS squelch logic input selection for J3 - RX Only port.

NOTE: J3B uses J3 Mini-DIN-6 pin-1 for CTCSS logic input. This is not standard and this jumper 
should only be placed when using radio connector adapters that map CTCSS logic to Mini-DIN-6 
pin 1.  Examples are the Motorola-16R, Tait-15R, Kenwood-25R, and Bridgecom BCM-6R Adapters 
available from Masters Communications.


JU4 - False PTT LED Illumination Protection:
Jumper JU4 is removed to enable this false illumination protection.  The jumper can be placed if 
this option should it create a problem for a particular installation.  The jumper simply shorts 
out the diode - and the default is installed.

Why is this false illumination protection and JU4 necessary?
Partial (or full) illumination of the PTT LED can happen if the radio adapter is connected to a 
radio that has a PTT switching voltage (bias) of less than 5 volts. This situation causes the 
RED PTT LED to partially illuminate. This can also happen with just about any radio when its
power is removed or the radio is turned off, falsely making it look like the radio is transmitting.
Placing JU4 disables the BAT43 diode protection - removing it enables the protection.

Default - JU4 is installed and the relay option selected.