Finally was able to get my homemade APRS transmitter working tonight! I’m using a Byonics TinyTrak 3 SMT TNC with a Parallax GPS, hooked to my Wouxun HT. There seems to be something weird going on with the PTT circuit that I haven’t quite figured out yet. The TT3 doesn’t always seem able to pull down the 5V PTT singnal on the handheld. I’m thinking about adding an external transistor if I can’t get it to work reliably.