Hi Tom, Well, if you could swap out the power supply that would be the easiest . If you don't have a spare one you may be able to find a loner. The next thing I would try is putting ferrite beads on all wiring that comes out of the air-conditioner. A third idea is that some VHF or higher harmonic might be getting in to the unit. So, you might try a low pass filter between the rig and the antenna tuner. That's all my thoughts for now. God bless, mark WZ0K God loves you! My personal prayer book. Add your prayer or pray for others at the following link. http://prayerbook.homewithgod.com/cgi-bin/prayerbook/multi.pl?131961113534708:24:0 http://lists.topica.com/lists/funhamradio. http://groups.google.com/group/funhamradio-list http://funhamradio.bloki.com