DRA-30 Headers and Jumpers:


Header - Jumper Summary:

JU1 - Install this jumper to enable AllStar Link COS - Remove for Digital. 
JU2 - Install this jumper to enable AllStar Link CTCSS - Remove for Digital. 
JU3 - Install this jumper to enable the Left Audio Output. 
JU4 - Install this jumper to disable PTT LED falsing protection. 

By default, we recommend NOT installing the jumpers on JU1 thru JU4 for VARA FM 
or other digital mode usage.  

Detailed explanation of these headers and jumpers:

JU1 and JU2 - AllStar Link COS and CTCSS logic inputs:
The hardware COS and CTCSS inputs (used for AllStar Link) are not needed for 
VARA FM or other digital modes. In fact, if something is connected to the COS 
and CTCSS (Windows Volume UP and DOWN pins) bad things can happen with digital 
programs. In addition, DCD (XDC) and/or other logic or control lines might be 
connected in existing installations using the KPC-3 or similar TNC. These functions
affect pins 2 and 4 on the DB9. These DB9 pins can be disabled by the absence of 
the "JU" jumpers at locations JU1 and JU2. As such, even if these pins are tied 
back to the radio somehow, it won't matter - their existence won't affect the 
operation of the DRA-30 for digital use. Jumpers can be installed into locations 
JU1 and JU2 to restore the AllStar Link functionality.

Plus, these hardware inputs may be implemented sometime in software - permitting 
DCD or some other digital feature, so I didn't want to limit the hardware from 
being able to use them in the future. 


JU3 - LEFT Channel TX Audio Output:
JU3 is removed to prevent the Left Audio Channel from being connected to the 
DB9. In many cases, the Right Audio Channel is used for connecting to the radio 
and the Left Channel is not used. In existing installations, there may be 
instances where this pin (8) of the DB9 is connected to something, and disabling 
the pin by removing the jumper is desired.

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 it 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 jumpers on JU1 thru JU4 for VARA FM 
or other digital mode usage.