I have the PM3000 and the SL40 all wired up and the airport phrequencies show up on the Skyview. I moved the airplane outside of the steel building to check out the GPS and radio. I got a GPS lock right away. I'm located 15 miles from the airport and nothing was between the airplane and the airport. I had to turn the radio volume way down to get rid of the excessive noise. The squelch on the PM3000 and the SL-40 would not work at all. By having the volume turned down to where I could still hear a little noise, I could pick up the airport. When they came on air the noise would go away and I could make out the conversation but it wasn't very loud. If the engine would be running I don't think I would understand the conversation. The PM3000 antenna cable is run from the back along side the ADAHRS wires. The ELT antenna cable is run to the back on the other side of the airplane. Any ideas of what might be the problem? I will appreciate any help with this noise.