Connecting a Palm Device with the Kenwood TH-D7A Radio – pocketAPRS

I discovered pocketAPRS recently and wanted to try it with my old Palm m100. It is at least 6 years old, so I wasn’t sure if it was up to the challenge.

One of the most difficult things of this project, was finding the pocketAPRS software! Unfortunately the project was discontinued in 2004, making it difficult to track down. If you do enough Google hunting and searching, you should be able to find a copy some place on the net.

I installed pocketAPRS on the Palm, using the Palm Desktop… just like installing any other piece of software for the Palm OS.

Next I needed to figure out how to physcially connect the Palm m100 with the Kenwood TH-D7A. The Palm m100 I have came with a serial sync cable which looks ike this:

Since the sync cable had a female serial connection I decided to try using the GPS cable I had made in a previous post. Sure enough the Palm m100 with pocketAPRS was communicating with the Kenwood once I switched the TNC mode to “packet”. Thankfully I had made another cable, so I could have both the GPS and Palm connected to the Kenwood TH-D7A.

I am now able to see APRS information and locations on the Palm m100. This is a much more compact way to use APRS, instead of carrying a laptop around.

Making a Cable to Go Between a GPS device and the Kenwood TH-D7

Although you can buy cables “pre-made” for connecting the GPS to the Kenwood D7, it seems to be in the spirit of ham radio… to build your own.
Hopefully these pictures will help you see what I did to get mine working.

Page 6 of Kenwood’s Documentation on Connectors was very helpful. However it doesn’t really say what to do with the “serial” port end of the cable. The TH-D7 manual mentions which holes are what, but obviously it can make a difference on which viewpoint (solder-side or connector-side) and whether it is a male or female port.

This cable has allowed me to connect a Magellan Meridian GPS and a Garmin etrex Legend to the D7. (NOTE: This was for use with the existing manufacturer cables that provide connections from the device to a DB-9 serial cable).

View of the front of the connector-side:

View of the top of the solder-side:

So a view from the solder-side shows the pins to be:


G = Ground
R = Red
B = Black (sometimes white)

A lot of this depends on the cable manufacturer. If for some reason it does not seem to be working, simply switch (R) and (B).

You’ll notice that I used the crimp style connector for this specific cable, since the wires were large enough. On another cable that had smaller wires, I used the crimp and then soldered to make sure there was good connection.

EchoLink Cable for an HT

EchoLink Cable for HT – $40

N8ARY has basic circuit diagrams for building the setup necessary to use an HT with EchoLink. Its pretty basic and simple to do (from the looks of things). I am sure it is something most “hams” could figure out, but its always nice to have something to reference when building yourself. The site is not fancy or galmorous.

If you aren’t feeling brave enough to build your own, he will sell you a pre-built one, that is tested to be working.

I personally appreciate it when someone is willing to sell something like this, but also is willing to give you the directions yourself. It implies to me that the person isn’t out to just make a quick buck, but is actually trying to encourage and grow the hobby.

Personally, I’ll probably try to build one myself, just for the sake of learning . I’ll probably also see if I can find more detailed directions elsewhere. In case I can’t find other directions, I figured it would be good to share this site with others.

Build Your Own GPS/APRS Tracker – FreeTrack 2.02

FreeTrack 2.02 – GPS to APRS Tracking Encoder

“This encoder will turn serial NMEA data from a GPS receiver into APRS format AX.25 data packets.
By using this hardware with a 2 meter ham radio and the freely available APRS computer software, you can track the location of the GPS on a map in real time. Latest release now supports the mic-e compressed data format for much smaller packets.

The unique aspect of the design is in how it creates frequency shift keying (FSK) tones with the PICs built in 4 bit voltage reference instead of a modem chip.
FreeTrak's built in configuration routines allow you to enter all it's parameters with any serial terminal program.”

Getting APRS working with my Kenwood D7A

I struggled to get APRS working with my Kenwood TH-D7A/G. The following things were done. I haven’t confirmed all of them were necessary…

On the GPS… (Magellan Meridian GPS)

    • Set speed to 4800Bps from GPS to radio.

On the Radio…

    • Made sure that GPS was sending information to the radio by using the POS button
    • Made sure that the radio was set for waypoints to be “….MGN” to work with the Magellan Meridian GPS I am borrowing.
    • Set Band A freqency to 144.390
    • Set Band A as the data band
    • Set Band A offset to “0.00” (default was .600)
    • Set CTCSS tone to ON for Band A (This is to squelch all the “modem” noise.)
    • Set My Callsign
    • Set My Icon
    • Set Data TX as AUTO
    • Set TX Interval to 2min
    • Set POS LIMIT to 150mi (help eliminate information I don’t care about)
    • *IMPORTANT* Set Packet Path
      From: RELAY,WIDE
      To: WIDE1-1,WIDE2-1
    • Pressed TNC so that ONLY TNC appeared (No “packet”).
    • Last but not least… pressed the “BCON” button.