Kamtronics KAM - $50
This is a basic mid 1980s digital interface. AFAIK it does packet, RTTY, FSK and AMTOR, which means it would be useful for 2m and HF things like APRS and maybe Winmail, etc.
'91 Toyota Pickup
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"To live is to suffer, to survive is to find some meaning in the suffering." -- Friedrich Nietzsche