DRA-70 Mini-DIN-6 Pinout: 1 = TX Audio - selected by JU5 - A = Right - B = Left (Default is Right) 2 = Ground 3 = PTT 4 = 9600 Baud RX Audio - Selected by JU8 in the "B" position 5 = 1200 Baud RX Audio - Selected by JU8 in the "A" position 6 = COS - Not normally used - (AllStar hardware COS input) OTHER OPTIONAL CONNECTIONS: Optional +12V = External Power for the Audio Amps (when JU2 is in the "B" position). Optional CTS = CTCSS hardware logic input used with AllStar Link. Header - Jumper Summary: JU1 - Normally in the "L" position. JU2 - Normally in the "A" position. JU3 - Normally removed. JU4 - Normally removed. JU5 - Normally in the "A" position. JU6 - Normally removed. JU7 - Normally removed - Install to enable VOX. JU8 - Normally in the "B" position. 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. Detailed explanation of these headers and jumpers: Jumper JU1 - VOX Input Selection - Controls which audio channel drives the VOX input. Position L = Left channel is sampled to drive the VOX Position R = Right channel is sampled to drive the VOX Default is "L". For detailed VOX operation, please see the article on the FAQ page. 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-70 for digital use. Jumpers can be installed into locations JU3 and JU4 to restore the AllStar Link functionality. Default is both are removed or side-stepped. 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 or RIGHT TX Audio Output to DIN Connector. JU5 selects between Left or Right transmit audio channels. A = Right, B = Left. Default is A - Right. 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. Default is removed. Why is JU6 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. JU7 - VOX Enable / Disable Jumper JU7 is placed to enable the VOX PTT feature. JU7 is removed to disable the VOX PTT feature. For detailed VOX operation, please see the article on the FAQ page. JU8 - Receiver audio baud rate selection. This header is right behind the DIN-6 radio connector. It's in a tight location and later units have a jumper with a (blue) handle to make repositioning a little easier. JU8 A = 1200 Baud, B = 9600 Baud receiver audio selection (radio dependent) Default is B - 9600 Baud. By default, we recommend NOT installing the shorting bar on JU3, JU4, JU6 and JU7 for VARA FM or other digital mode usage.