[Elecraft] KAT500 no PC comms

[Mike Dodd]

Elecraft is taking a l_o_n_g time to repair the USB port on my K4d, so I 
bought a used K3 (non-s) as a backup rig. It works fine, and interfaces 
correctly with my KPA500 and KAT500. (The KAT is already configured for 
all frequency steps on all bands, and I can hear the KAT relays click 
when I change bands.)

But the KAT Utility doesn't connect to the KAT.

I'm using the same Computer interface cable plugged into the same USB 
port on the PC. Windows Device manager says it's working.

With a K4, does the KAT communicate with the PC via the K4's USB 
connection, which he K3 doesn't have?

What am I missing?

73, Mike N4CF