Aircraft with the older NavWorx MLB100, Skytrax100:

These units are no longer repaired. 

Avidyne's current shipping product is the Skytrax200; a new purchase is required, there are no trade-ins or upgrades.

Antenna requirements for the Skytrax200 (ST200), as of 2021:

Pilots adding the ST200 must ensure they are working with an Avidyne dealer to ensure they have the correct antenna. 

When adding the AXP340 and the Skytrax200:

You must install a sperate antenna for the ST-200.

Avidyne does not recommend a Duplexer, as this would not block the output power from damaging the receiver input of the ST-200.