I installed the Navworx ADSB box this week end. The traffic is amazing, up to 28 targets on Sunday evening while flying over the top of Atlanta Hartsfield. However, the one problem I noticed was that if you looked carefully you would see a yellow target right underneath your airplane, colored yellow. It always matched my altitude, and since I wasn't getting an audio traffic warning, I concluded that it was being presented by the ADSB and not the TIS from the Garmin 330. I spoke with Bill Moffit and ran another wire last night, and configured the ADSB to accept the squawk codes from the Garmin 330 and on this morning's flight the ghost target was gone.
So here is the fix:

Run a single conductor shielded wire from either RS232 1 or RS232 2 of the 330 transponder to pin 33 of the ADSB box. Pin 33 is not documented for this purpose yet, but it works. We are already using pin 7 for the AFS serial altitude out to the ADSB, so pin 7 is unavailable. Configure the 330 for REMOTE + TIS. Then, using the PC attached to the maintenance port of the ADSB send the command TXCP GTX330. You can verify it is working by putting in a code other than 1200 in the 330 and then use the READ ALL command to the ADSB and see the new Squawk code in the ADSB box.

It was NOT fun getting upside down to install this wire to the back of the 330! Hopefully, this will help those who are still in the wiring phases.

Vic