DRA-45M REV2 Header - Jumper Assignments: Header - Jumper Summary: JU1 - Normally in the "B" position. JU2 - Normally in the "A" position. JU3 - Remove this short "shunt" to disable AllStar Link COS (Remove for Digital) JU4 - Remove this short "shunt" to disable AllStar Link CTCSS (Remove for Digital) JU5 - Remove this short "shunt" to disable the Left Audio Output JU6 - Remove this short "shunt" to enable PTT LED falsing 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 JU6 - but not required. In the transistor position - select the position of JU6 as required and detailed below. H1 - Install short over the center two pins of this 4-pin header. H2 - Install short over the center two pins of this 4-pin header. H1 and H2 are white 4-pin headers directly beside the LM-386 amplifiers. By default, a jumper short or "shunt" is installed onto the center two pins of the header. See the "H1 and H2 header pin assignments" document for details. By default, we recommend NOT installing the short on JU3 thru JU6 for VARA FM or other digital mode usage. Detailed explanation of these headers and jumpers: Local Control or Alarm Trip is a logic option that can enable a secondary control method, or trip an alarm. This feature is capable of toggling a control method or tripping an alarm line on a co-located repeater controller or other remote alarm if the DRA-45 should fail. JU1 controls the polarity of this function, explained below. Jumper JU1 - Control / Alarm 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. Default is position "B" 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 5 volts. Position B = Amplifiers powered from external source 6 to 15 VDC. Some radios require more than 5 volts P-P of audio. Many radios have a source of 10 to 15 volts readily available. The voltage source 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. Default is position "A" Jumpers JU3 and JU4 - 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 JU3 and JU4 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-45 for digital use. Jumpers can be installed into locations JU3 and JU4 to restore the AllStar Link functionality. Default is both JU3, and JU4 is removed. Plus, these hardware inputs may be implemented sometime in software - permitting DCD or some other digital feature, so I don't want to limit the hardware from using them in the future. JU5 - LEFT Channel TX Audio Output: JU5 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. Default is installed. Remove for reuse of Kantronics cables. JU6 False PTT LED illumination protection: Jumper JU6 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. Place this jumper when using the relay PTT keying selection. 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 JU6 disables the BAT43 diode protection. Default is JU6 is removed, but place this jumper when using the relay PTT keying selection. By default, we recommend NOT installing the shorting bar on JU3, JU4 and JU6 for VARA FM or other digital mode usage. Remember to also remove JU5 when using or reusing of Kantronics radio cables.