I use an AH4 on my 756PRO on 160m with no problem....the kicker is you must have a good amount of wire in the air for it to tune. Don't expect it to tune 20' of copper to resonance. I have used it with great success on 160m thru 6m. I have 130' of wire in the air fed against a ground rod and two radials. Phililp KA4KOE