so ive been running APRS for a few months now, mostly just for position tracking when i go out portable, and that part works fine — i can see my callsign popping up on aprs.fi no problem. but i tried sending a message to another local ham yesterday and he never got it, and i also tried sending one to my own station from aprsdroid on my phone and nothing showed up in my TNC log.

my setup is a kenwood d72 going into a kantronics KPC-3+ and then into a 2m antenna, running 25w. path is set to WIDE1-1,WIDE2-1 which i thought was standard. i can see my beacons digipeating through the local fill-in digi and hitting the igate so its definitely getting to the internet side. just the messaging piece that seems broken.

anybody dealt with this before? wondering if its a config thing on the TNC or something with the d72 settings. didnt change anything recently that i know of.

the position beacons and APRS messages are two different animals even though they travel on the same 144.390 frequency. one thing to check is whether your igate is actually two-way capable — a lot of igates out there are receive-only, meaning they'll pull your packets off RF and push them to the APRS-IS network but they wont inject anything back down to RF for you. so messages sent to you from the internet side just never make it back over the air to your TNC.

go to aprs.fi, find your nearest igate and click on it. if it says something like "IGate, TX capable" or shows two-way operation then thats fine. but if its just listed as a receive gate you're kind of in a dead end for incoming messages unless theres another two-way igate in range. the messaging between two RF-only stations should still work if you're both in range of a digipeater, but thats a different path than going through the internet side.

yeah what he said about the igate is probably it. also worth double checking that the destination address on your message packets is set right on the KPC-3+. i had a similar issue a while back and it turned out my TNC was somehow mangling the message format, took me forever to figure out because the beacons looked totally normal on the waterfall. ended up just reflashing the firmware and reconfiguring from scratch which was annoying but fixed it.