From reading through the posts, it would appear to me that the MOA was introduced after the tragic Radio City incident. However, there has been mention of the link to the Cobra Mist installation. If it began testing in late 1971, based on a design from 1961, then the arrival of RNI in 1970 must have set alarm bells ringing. Using 6 - 40Mhz, I would think the last thing you would want is a 49mb and 31mb transmitter almost in line with the main lobe? I'm sure someone will shoot me down, but was this the real reason it was jammed?