Hi all, Is anyone using the ANC-4? If so do you find it effective? Do you find the exterior antenna necessary? I have developed a noise about every 10 Khz on 80, 40 and 30 meters, it sounds like a flurescent light noise but none are in the house. Any help or comments . Thanks, Vince Santis, N1VS QRP-L #2372 Winsted, CT