Colorado Traffic Net

"Specializing in the first and last mile of NTS delivery in Colorado."


APRS 51TNC configuration example

The following are screenshots showing how we configured an APRS 51TNC (also known as APRS ANT51) to operate as a receive-only iGate. We recommend that you start by copying these settings that worked for us. If you want to change settings from there, modify the settings one factor at a time, testing after each change, to eventually suit all of your needs and preferences.

The first thing to do when you take it out of the box is to hook it up to your router via Ethernet and power up. Look in your router's configuration and determine the IP that the router has assigned to the APRS 51TNC. It may take a few minutes to show up. In our case it is but make a note of what your unit's IP is. Next, download and run the software on a Windows machine on the same network.

English software: APRS

If you have trouble installing the program, make sure you first install .NET 4.0 framework. Copy the contents of the "OCX Files" files folder in the archive above and put them into 'C:\windows\syswow64\'. Next, open CMD with admin rights (startbutton -> type cmd-> open cmd with right mouse click 'run as admin'). Change directories to find your way to 'C:\windows\syswow64\' and run each of the 3 files that you just copied with regsvr32.exe, ie. 'regsvr32.exe mscomm.ocx', 'regsvr32.exe tabctl32.ocx', and 'regsvr32.exe MSCOMM32.OCX'.

Enter the IP into the "TNC IP" field. Then click "Connect" and then "Read". You will use "Write" later to send the configuration to your unit. You may see some errors on this first tab, but when you get everything else working in the later steps, your "State" tab should end up looking something like this...

Use the "Network" tab to assign the static IP. The IP address shown in the "51TNC IP" section below should be the same IP that you used before, not necessarily what is shown in my configuration below. Fill in the rest as shown.

Do not add a SSID to your call sign in the "Callsign" field, just leave only your plain call sign in that field. The "ID" value of "5" showing is the APRS SSID of the unit, for example "N0CALL-5" is what would show in these settings. We suggest using a SSID of "5" like we have since it is standard for iGates.

There are various ways to attain the 5-digit APRS-IS passcode for your call sign, just search for "get APRS-IS passcode".

For the APRS.IS servers, you can try these until you find one that works for you. If you have a better IP to suggest, please let me know at the email address on the QRZ page for k0xk.


In the "Beacon" tab, we set up this iGate to display the standard icon for a receive-only iGate .

You will have to convert your GPS coordinates into the APRS format. For example...

4903.50N is 49 degrees 3 minutes 30 seconds north
07201.75W is 72 degrees 1 minute 45 seconds west

Many of the settings in the "T N C" tab are default. The "DIGI ON/OFF" section allows you to perate as a digipeater. We recommend only playing with these settings once you get it working as a receive-only iGate, testing each change incrementally as you make them.

Many of the settings in the "G P S" tab are default.

We do not show the last two tabs that have no settings and are for logging and diagnostics. We hope this guide helps, and thanks for helping out with APRS! If you are really stuck with something, you can message the Colorado Traffic Net on our Facebook site.

Links to other sites about the 51TNC:

If you have any improvements to suggest for these instructions, please email Zeke Ragsdale k0xk at his e-mail address on his QRZ page.