Monday, August 15, 2011

Kenwood TH-D7A, D7AG, Garmin Foretrex 201-APRS

A while back I mentioned using a Garmin Foretrex 201 for doing APRS with my TH-D7A radio.

I listed this website etc.

I finally got around to building the patch cord. I got a 'scanner to phone' set of patch cords from radio shack for $6...I thought this would require the minimum of hassle.

It came with 4 cords, the one I used was the 2.5 to 3.5 mini stereo cord. Now both the Garmin and the Kenwood use a 2.5, so I picked up an adapter...that way, if I need to, I can put the GPS on an extension cord for better satellite reception.

I had to modify the cord (as described in the link) by swapping the TX/RX signals. This amounts to slitting the cable down the middle for an inch or so, carefully pulling out the Red and Brown wires, cutting them, then solder the red to brown and vise versa.

So I did all that, hooked it up to my D7A and nothing...I rechecked the solder job...played with all the settings, but still nothing on the D7A (it should chirp with the new GPS info, and on "My Position" it should show the correct lat/long)

Well...I decided to test it on my D7AG just to see if is a radio issue.

Immediately worked on the D7AG...

So I searched the internets, and found out that my D7A was an older firmware model (SN 008000xx) , and only can read GPS coord to the hundreds. The newer firmware (SN 010 and newer) can take coord to the thousands.

So some GPS devices are compatible, some are not...the Foretrex 201 is I can only use it with the D7AG, not a total loss, since the "G" model has much more advanced APRS commands.

I will be using this setup in a chase vehicle for a famous bike race in August. I picked up a 'pistol case' to put all my radio accessories in for portable use. This GPS is the last item.