I am pretty sure it is the electric fuel pump, because when I turn the key to the on position, the noise appears, then after a few seconds, it disappears. I don't think it is ignition, because at this point the motor is not running yet. The antenna is located on the spare tire carrier, at the rear of the vehicle. I have a ground strap going from the ground stud on the antenna mount to the frame, then another one from the body to the frame. I also have a ground stap going from the frame to the exhaust system, and one from the hood to the body of the truck. If I take the antenna off of the mount, the noise dissappears totally. The fuel pump is the only thing that I think it could be, but I am up for any suggestions that you might have. What is discouraging, is the fact that when I turn on the noise blanker of the Alinco DX70TH, the noise level will drop down to S1 or S2, but SSB is now garbled, and is hard to understand.