AMI to GTX How To Page

1 Make up a wiring harness to the 16 pin accessory connector.

You will need to connect to pins

1- External Speaker -

2- Mic Audio

3- PTT

4- Ext. Alarm

7- Ground

10- Ignition Control

14- Hook

15- RSSI BUF (Used for Cos)

16- External Speaker +

(Note I used the external speaker output for this configuration instead of pin 11 Flat RX Audio, I don't know why, but I'll have to try that method next.)

I set my GTX;s volume pot to approx 1/2 and marked it so I know where to leave it.

You will also need to connect the 1/8 to 1/8 mono cord between the AMI PC Mic jack and your PC's Mic jack on the sound card.

Supply power to the AMI.

Attach the DB9 serial cable between the AMI and your COM port.

Parts I used were

4- 1/8 mono plugs

1- 1:1 turns audio isolation transformer

1- 1/8 to 1/8 mono cord

1- DB9 serial cable

1- 16 pin accessory plug with 9 flying leads

1- Resistor

GTX Mobile Accessory Jack Pins and Signals

Pin # Signal Name Description and Usage

1 EXT SPKR - Connect to an external speaker with pin 16

2 EXT MIC AUDIo Microphone-level audio input

3 EXT PTT Push-to-talk input

4 EXT ALARM Active low output to drive a relay

5 FLAT TX AUDIO Line-level audio input

6 SCI DATA IN Not used

7 GROUND Ground for PTT and audio - NOT FOR SPEAKER

8 SCI DATA OUT Not used

9 EMG SWITCH Low input activates alarm functions in radio

10 IGNITION CTRL Must be pulled high to let radio turn on

11 FLAT RX AUDIO Flat receive audio output

12 GP I/O Not used

13 INT SPKR Connect to pin 16 to activate internal speaker

14 HOOK Low input to activate RX PL/DPL

15 RSSI BUF Analog output of rcvd signal strength: 1.5 - 4.5 VDC

16 EXT SPKR + Connect to an external speaker or pin 13

If you are going to use an auxiliary radio for control, Connect the audio source from that radio to the AUX Input of the AMI.

This input is only active when the link is transmitting a signal from the internet.

Download Echolink and check SYSOP. Make sure you put the -L or -R after your callsign.

Plug the DB9 serial cable between the AMI and the COM port of the computer.

Apply power to the AMI.

The jack may be wired opposite to convention with the center pin being - and the outer shell +.

There is circuitry inside the AMI that allows wiring either way, Just follow the recommendations by WB2REM for your model's revision.

ECHOLINK SETTINGS

RX CONTROL Set to SERIAL CD

TX CONTROL Set to ASCII (Note: Do NOT check 9600)

TX TIME LIMIT Set to 180 Seconds

HYPERTERMINAL

The COS polarity can be adjusted using Hyperterminal. (Hardware change)

(There is also now a check box in Echolink to change it) (Software change)

In my computer it was START/ All Programs/ Accessories/ Communications/ Hyperterminal to bring up the program.

The Hyperterminal settings are 2400, N, 8, 1

The letter commands are :

? Gives status of the board

R Receive

T Transmit

L Sets the TX Time limit

I Sets the polarity of the COS

LINKS

http://www.ilinkboards.com/

http://www.ilinkboards.com/echolinksetup.html

http://www.repeater-builder.com/motorola/gtx/gtx-index.html

http://www.echolink.org/

--- Disclaimer ---

These settings worked for me.

They may not work for you.

This is only a description of what I did to get my node on the air.

Your results may vary.

Proceed with caution.

I used pin 15 of the accessory connector for my COS signal.

This is the RSSI BUF which is an Analog output of received signal strength. On a received signal is puts out -----Volts and at idle it is ----Volts.

I needed to add a pull down resistor to the COS circuit due to the fact that the AMI wants to see a voltage swing of Above and Below 1 volt. With a ----K resistor between the + and - leads my voltage at the plug going into the AMI COS port is ----v idle and ---v active.

I also jumped pins 4 and 10 together. Pin 4 feeds voltage to pin 10 to satisfy the ignition control circuit.