I have used a half dozen models of emitter with harmony and they all work fine.

To be clear i am talking about 1 output = 1 emitter. If you are trying to stack emitters or use blinking emitters you may need to read post 2 and 3 again.

You also need to think about the IR jack on the back of the "hub". You didnt mention a model and i dont have experience with all versions of logitech harmony but some (maybe all) have mini mono 2.5mm jacks instead of the typical 3.5mm emitter jack that most IR emitters have.

[Link: a.co] will solve that issue for you.