RA-47M Jumper Assignments:

Jumper Summary - 

JU1 - 1200 / 9600 Baud receiver audio selection. 
JU2 - LEFT or RIGHT TX audio selection.
JU3 - Squelch logic input selection.
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.

NOTE:
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.

JU1 - Receiver audio baud rate selection - 1200 or 9600 Baud. This header is beside the 
Mini-DIN-6 radio connector. Selects between Mini-DIN-6 pin 5 (1200) or pin 4 (9600).
Default is 9600.

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

JU3 - COS / CTCSS / or NONE -  Squelch logic selection.
This header has three valid jumper positions:
COS
CTCSS
NONE (jumper totally removed or hung on the center pin only)
Selects which C-Media squelch logic input is connected to Mini-DIN-6 pin 6.
Default is COS.

Jumper JU4 - False PTT LED illumination protection.
Jumper JU4 is removed to enable this 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.

Why is this 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 is the case with many
 portable radios.  This situation causes the red PTT LED to partially illuminate. This 
illumination can also happen with just about any radio when the radio's power is turned off, 
falsely making it look like the radio is transmitting. Placing JU4 disables the BAT43 diode 
protection.
By default, we recommend NOT installing the JU4 unless the relay keying option is chosen,
then - JU4 should be installed.