Back years ago, I rebuilt a halicrafters SX28A Super Skyrider. This was in the late 60's early 70's and I went off to school and sold the receiver. While I was aligning it, that dastardly woodpecker would drive me nuts. I now have a Grundig 800 and haven't heard anything like the woodpecker noise. Anyone know what it was or what it could have been? I read many conjectures like it was the US' over the horizon radar or it was Russia's or even China's but never heard what it really was. ??