This is a working APRS transmitter/receiver patched together from three components held together by Velcro.
Transmit and receive is handled by an old Kenwood TH-K2 2M HT salvaged from the junk box fitted with a new battery. It has adjustable squelch and VOX, both essential for APRS operation.
The Kenwood is controlled by APRS Pro, the best iPhone APRS app which includes a software TNC. That allows operation through APRS digipeaters via VHF transmission, rather than through cellular to Internet connections, which is the usual mode for smart phone APRS operation. It's running on an iPhone 5 which had been sharing the same junk box as the TH-K2.
The new component in this setup is the interface between HT and iPhone, Easy Digi. Easy Digi provides the proper cabling between the two other components, and isolation circuitry without which all sorts of anomalies occur. Fortunately, the input and output connections of the TH-K2 are identical to the popular Baofeng HTs. It is shown here sandwiched between HT and iPhone.
To view packets forwarded to the Internet from K2RHK's NYC iGate click
To view a screenshot of packets click