Hi Mike,
Can a Kam KPC-3+ used for VHF packet work?
Your TNC should work well ... monitor on 145.800 and 145.825 MHz with PASSALL = ON in the TNC. The 145.825 frequency is the one usually used for spacecraft APRS packet but the ISS has been on 145.800 up & down for digipeating this past week.
While the syntax of the commands you type into your TNC may differ from the examples I used for an MFJ TNC-2 you can likely get on the air with the settings I have summarized at: http://home.comcast.net/~k9jkm/ARISS_Packet_How_To/
ISS digi is workable with less than 5 watts and a 2M vertical. PCSAT is workable when its in full sunlight and I generally have better luck with a small (3-element) 2M beam on that bird.
-- 73 de JoAnne K9JKM [email protected] Editor, AMSAT News Service Copy Editor, AMSAT Journal