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Kenwood TK-7180 / TK-8180 NX-700 / NX-800 Mobile Radio Accessory Connector Notes Compiled, HTML'd and maintained by Mike Morris WA6ILQ |
Comments, suggestions, corrections to this page are welcome... Just drop a note to the author... (even one that just points out a typo)
The accessory connector is a DB-25 female mounted into the rear of the radio. It's J701 on the schematic (pages 47, 54, 72, 73 and 74).
The second column of the table below is the name in the Kenwood manual.
| DB-25 Pin # |
Signal Name |
Description | Notes |
|---|---|---|---|
| 1 | NC | No connection in a stock radio. | RSSI can appear here after modification, output level is 0.8 to 2.3 volts. |
| 2 | RXD1 | Serial data input #1 | RS-232C level. Input voltage range : +/-30 volts max. Low less than 0.4 volts, high greater than 2.4 volts, input impedance 5 K ohms. |
| 3 | TXD1 | Serial data output #1 | RS-232C level. Low less than -5 volts, high greater than +5 volts, output impedance 2 K ohms. |
| 4 | AUXI/O9 | AUX input/output #9 | Active low with 47 k ohm pull-up to +5 volts, can be programmed for external PTT. |
| 5 | DI | Data signal input | Data Input, level adjustable (2.0 volts p-p typical), flat audio input (no pre-emphasis). Use this for external PL, DPL or data input. |
| 6 | MI2 | External MIC input | DC coupled, external transmit audio input (will be pre-emphasized). |
| 7 | GND | Ground | |
| 8 | AUXI/O8 | AUX input/output #8 | Active low with 47 k ohm pull-up to +5 volts. |
| 9 | TXD2 | Serial data output #2 | TTL level, output impedance 1 K ohms. Low less than +0.7 volts, high greater than +4.2 volts. |
| 10 | RXD2 | Serial data input #2 | TTL level, input impedance not specified. Input voltage range: +5.0 volts max, low less than 0.8 volts The GPS accessory that provides automatic vehicle location for Passport Trunking injects the data stream here. |
| 11 | GND | Ground | |
| 12 | AUXI/O7 | AUX input/output #7 | Active low with 47 k ohm pull-up to +5 volts. |
| 13 | AUXI/O6 | AUX input/output #6 | Active low with 47 k ohm pull-up to +5 volts. |
| 14 | SB | Power output after power switch | Switched DC power out, 2 amps maximum (fuse it!). |
| 15 | AUXO2 | AUX output #2 | Open collector (500 mA max) Low less than 0.3 volts. |
| 16 | AUXO1 | AUX Output #1 | Open collector (500 mA max.) Low less than 0.3 volts. |
| 17 | AFO | RX filtered audio output | DC-coupled. Low level receiver audio out (de-emphasized). Wide or narrow, 700 mV p-p typical. |
| 18 | GND | Ground | |
| 19 | DEO | Detected signal output | DC-coupled. Flat audio output, 740 mV p-p typical (discriminator audio). |
| 20 | AUXI/O5 | AUX input/output #5 | Active low with 47 k ohm pull-up to +5 volts. |
| 21 | AUXI/O4 | AUX input/output #4 | Active low with 47 k ohm pull-up to +5 volts. |
| 22 | AUXI/O3 | AUX input/output #3 | Active low with 47 k ohm pull-up to +5 volts, programmable for COR or TOR. |
| 23 | AUXI/O2 | AUX input/output #2 | Active low with 47 k ohm pull-up to +5 volts. programmable for COR or TOR (whichever one you didn't put on pin 22). |
| 24 | AUXI/O1 | AUX input/output #1 | Active low with 47 k ohm pull-up to +5 volts. |
| 25 | ME | MIC Earth (ground) |
Pins 6, 17 and 19 are noted as DC coupled. Use a coupling capacitor in line with any external device. Many external devices have an internal series capacitor, but not all...
The external speaker output is a 3.5mm / 1/8 inch jack (labeled SP) that is adjacent to the accessory connector.
Connections to an external repeater controller...
Using the TK-7180 or TK-8180 as a receiver or a transmitter...Remember that this is a mobile radio with a heat sink designed for a low duty cycle... Yes, it can be used as a remote base or as a repeater transmitter, in fact at one site I have five UHF commercial repeaters using five pairs of 8180s, one as the receiver and a second as the exciter (set for five watts out) driving a Henry Electronics continuous duty amplifier (5 watts in, 100 watts out). Controller power comes from pin 14 on the transmit radio and ground.
The PTT, Transmit audio in, Repeat audio out, COS, PL / DPL Decode, etc. interfacing connections to an external repeater controller... RLC, Arcom, Scom, etc. are very similar to the TKR-750, TKR-850, NXR-710 and NXR-810 repeaters. Each of the AUXI/O pins can be indivually programmed to any one of several functions including COS, PL / DPL Decode, Channel Steering, External PTT, and more. The 7180 / 8180 interface very similar to the KR-750, TKR-850, NXR-710 and NXR-810 repeaters.
The most common configuration that I have found is:
| DB-25 Pin # |
Kenwood Name |
Mode | Notes |
|---|---|---|---|
| 4 | AUXI/O9 | Input | Can be programmed for External PTT. |
| 5 | DI | Input | Data Input, level adjustable (2.0 volts p-p typical), this is a flat audio input (no pre-emphasis or other audio processing), if you need it this can be used as an external PL, DPL or data input. |
| 6 | MI2 | Input | DC coupled, external transmitter audio input (will be pre-emphasized). |
| 7 | GND | — | Ground |
| 11 | GND | — | Ground |
| 14 | SB | Output | Switched DC power out, 2 amps maximum (fuse it!). |
| 17 | AFO | Output | DC-coupled, repeat audio output (de-emphasized) wide or narrow 700 mV p-p typical. |
| 18 | GND | — | Ground |
| 19 | DEO | Output | Detected signal output, DC-coupled, flat audio (discriminator audio) output. An external PL, DPL or data decoder can connect here. |
| 24 | AUXI/O5 | Output | Programmable function input or output #5, Can be used for receiver TOR (CTCSS / DCS decode). |
| 25 | AUXI/O6 | Output | Programmable function input or output #6, can be used for receiver COR (COS). |
As noted above pins 6, 17 and 19 are DC coupled. Many external devices have an internal series coupling capacitor, but not all...
Some systems have the users running their receivers in PL decode mode full time. These systems control the CTCSS / DCS transmitter encoder to keep the repeater ID from being heard. This can be accomplished with pin 23, AUXI/O4, and set it for QT/DQT (CTCSS / DCS) encoder control.
One convenient method of connecting any radio to a repeater controller: Take a common VGA cable (a common computer monitor cable) and chop off the connectors. You will find three shielded conductors (was used for red, green and blue) and seven individual conductors. Use the shielded coductors for RX audio, TX audio and external PL Encode audio (if you need it), and the 7 conductors can be used for everything else... ground, COR, PL Decode (TOR), PTT, etc.
Contact Information:
The author, Mike Morris WA6ILQ, can be contacted here.
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This page created on 30-Jan-2022 by Mike WA6ILQ.
This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.