iFly GPS Forum

Both types of ADS-B use transponders.  If you're using a UAT ADS-B transmitter (978 MHz), you're using that in conjunction with a Mode C transponder.  (You're not just picking up the altitude from the transponder -- the transponder has to be present and working.)  If you're using Mode S ADS-B (1090 MHz), you're uisng a Mode S transponder with ES to do that (it serves as both a transponder and an Extended Squitter, which sends the ADS-B data).  So, regardless of flavor, you need to keep your transponder in working condition, which means it needs to get a checkout every 2 years.

ADS-B is not just about the new data that gets sent out (tail number, ICAO code, etc), it also still requires the transponder functionality.

It seems like they could make the SkyBeacon fit the 70's and later Cessna droop wingtips with the fabrication of a new fairing (the part on the existing light that secures the glass globe).  Not sure if the planned STC will cover changing the fairing on it, but since the number of Cessnas out there with this wingtip, it seems like it would be worth getting it approved (unless the fairing change can be made as another Minor Altercation).  Otherwise we would have to go with the TailBeacon.  I will need to do that with my Grumman Yankee.