ICOM IC-92 GPS feed

As I discovered earlier it is possible to feed the ICOM IC-92 with external GPS sources instead of the original external microphone. One way is to use the programming cable OPC-1799 with a null modem cable. Here GPS data can be transmitted to the radio with 19k2 bauds. But as I setup a little interface box using the original cable for the HM-175GPS mic I found out that the two wires RX and TX are not wired up in the spare part that I ordered. So there had to be at least one other way to transfer GPS data to the radio.

I took a look into the service manual of the original HM-175GPS mic and identified a pin named “NMEA”. This is connected to the GPS unit inside the mic via a level converter. Additionally this wire was marked with a notice saying that this line is obviously driven with TTL levels.

As I had a spare GPS unit ublox NEO-6M at hand that is able to output the GPS data in various forms. The default setting is 4,800 baud with TTL levels. So I made a quick and dirty setup an wired the VCC pin of the GPS module to the +5V pin of the radio as well as the TX pin on GPS unit side to the pin named “NMEA” on the radio connector (see here for example).

Ublox neo-6M GPS module wired up to IC-92

Measuring the power consumption showed ca. 70mA which is a little more than the GPS module by ICOM consumes. I hope that the internal voltage regulators will not be overburdened :). A quick test outside showed that the GPS data can directly be processed by the IC-92 radio. The GPS module received a fix within 2 minutes and shows this with a blinking blue LED.

IC-92 with GPS data fed from an external module

Long term tests will show if the radio is ok with a little more current drawn by the GPS module. So the next D-Star transmission from the bicycle will inlcude GPS data configured according to my post here.

Please be aware that any modification to your radio may lead to a loss of warranty. Use this information at your own risk. I am not responsible for any damage to your equipment.