Dennis Tierney

IT ALL STARTED one Sunday afternoon last fall. Our club had adopted the recommended frequency control system that had several frequencies grouped on each pin. I had two planes with me, and each was on a different frequency. No one else was on either frequency, but by club rules I couldn't fly either plane because someone was flying on yet another frequency. I decided to do some investigation into the purpose behind the frequency groupings. It didn't take long to discover the terms Second Order and Third Order Intermodulation interference. All the magazines were talking about the results of the inter-