RA-33M Jumper Assignments:

Jumper Summary - 

JU1 - Selects the "Local Control" logic polarity.
JU2 - Audio amplifier powering - select between USB 5V and a external 12V power source.
JU3 - Local Control or TX CTCSS option select pin.
JU4 - Remove this jumper to enable PTT LED false illumination protection.
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 JU4 - but not required.  In the transistor position - select the position of JU4
as required and detailed below.

Local Control is a logic option that can enable a secondary control method.  Some repeaters 
only require one logic lead change to enable internal controls. Not all repeaters have this 
control revert option, but for the ones that do, the RA-35M can feed such a line directly.  
This feature of enabling internal controls will allow the repeater to operate locally if the 
Asterisk application, computer, or RA-33M should fail.  JU1 controls the polarity of this 
function, explained below.

Jumper JU1 - Control Revert logic polarity.
Position A = DB9 pin 7 Logic is high when COMM OK LED not lit.
Position A = DB9 pin 7 Logic is low when COMM OK LED lit.
Position B = DB9 pin 7 Logic is low when COMM OK LED not lit.
Position B = DB9 pin 7 Logic is high when COMM OK LED lit.

Jumper JU2 - Audio filter powering source selection.
Position A = Audio filters powered from USB 5VDC. Suitable for many radio applications where the 
maximum required P-P voltage doesn't exceed 4 volts P-P.
Position B = Audio filters powered from external source 6 to 25 VDC.  Some radios, like the 
Yaesu System Fusion, requires more than 4 volts P-P of audio. Many radios have a source of 
10 to 15 volts readily available.  Must be well filtered but regulation isn't necessary as 
long as enough current is available for the load.

Jumper JU3 - Local Control or TX CTCSS select pin.  
Position A puts the internal controls revert option to pin 7.
Position B puts the TX CTCSS logic to pin 7. 
Since there aren't enough pins on the DB9 to bring the TX CTCSS function out to its own pin, 
it's routed to the DB9 (pin 7) as a jumper selectable option.

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, and transistor keying mode is 
selected.  This situation causes the red PTT LED to partially illuminate. This 
illumination can happen with just about any radio when the radio's power is turned off, 
falsely making it look like the radio is transmitting. Removing JU4 enables the BAT43 diode 
 / false illumination protection - in transistor keying mode. False PTT LED illumination doesn't
happen when relay PTT keying is selected at the PTT jumpers.

By default, we recommend NOT installing the JU4 unless the relay keying option is chosen,
then - JU4 should be installed.