RA-42 Jumper Assignments:


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-40 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-42 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 amplifier powering.
Position A = Amplifiers 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 = Amplifiers powered from external source 6 to 15 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.  Driving speakers will require a power 
  source capable of several hundred mA., depending on speaker impedance and desired listening 
  level.

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.  
If a user only wanted a LED as a status indicator, the jumper position is unimportant, as the 
  yellow LED will illuminate no matter the position or existence of jumper JU3.

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.