RF question -- Plane radio aliasing? I hope this is the right place to post it. My buddy and I were working on a jet earlier and turned on the HF communication system to perform an operational check out of the system. We tuned the radio to 2.5 MHz and picked up a local AM radio station. The station is 1250 KHz. Why are we able to receive this frequency when tuned to another exactly twice the frequency? We tried it on another jet and got the same thing. I searched google and couldn't find anyting. Any help would be awesome, thanks.