Sep 3, 2013

Installing Winlink 2000 with Winmor and ICom M801E

N 53° 52.456', E 8° 42.350'

We finally got our new ICom M801E SSB radio working with ham frequencies opened. Our first QSO to Finland from Cuxhaven, Germany, was successful.

Besides marine radio and ham station we were naturally interested in receiving email and weather reports. Most of the people use Pactor modem for this, but we decided not buy it unless it was absolutely necessary. It looks like it's not. Good, because it's very expensive, more than 1000 euros. 

ICom M801E user manual is just for the marine radio, it's very limited and also contains some errors. The radio has a AF/MOD and a Remote D9 connectors for the external modems. 

Knowing that M801E is almost the same device as the American version M802, I was able to find more information.

There must be other ways to do it, but this is how I got this working.

Remote interfaces baud rate is 4800. I am using RS232C interface and no handshaking. This means 3 wires for the radio remote handling. You can use a normal PC to modem cable. Pins are one-by-one.

AF/MOD interface has pins 1-2 MOD pins to radio input and 3-4 AF pins to radio output. These can be connected to a sound card. AF to line-in or mic and MOD to headphone or line-out.

So far this is quite simple. The problem is with the PTT (push to talk) handling. Icom controls the radio frequencies by using the remote interface, but it doesn't handle the PTT. AF/MOD has pin 5 for PTT. If pin 5 is grounded, it puts the transmitter on.

Pactor has a relay for this purpose. RMS express has a feature to use rs232 RTS or DTR pins to control PTT.

I don't need a relay, because the currencies are minimal. Just one transistor is enough. 

I just happened to have one small device stored, that was not working, which had one npn and one pnp transistor and 10Kohm and 220ohm resistors. I used the npn transistor 1N 3904 as a switch. 10Kohm resistor somehow limits the quite high RTS voltage in base. Because I didn't have anything else to use there was no need to make any Ohm's law calculations. 

Collector is connected to AF/MOD pin 5 and emitter to ground. 

As it happened, it worked very well.

First version of the junction circuit.

The full documentation, but better than Icom manual :)

The Creative X-Fi usb sound card we use for the purpose (because we had it) and the necessary cables including the hi-speed and lo-speed NMEA for the radios and navigation.

The settings we are using.

I don't say this is the final settings, but at the moment it's working all right.