Mast e pre contest

The only thing I’m not comfortable with in these pictures is the falling derrick which in my opinion was far too heavy and totally over-complex. We added a vertical bar to reduce the bending movement – and to keep the geometry correct when the mast was vertical and the falling derrick was horizontal. I think the idea of a long (9m) falling derrick was important, so I’d sleeve a small steel pole onto a half-sized (3m) aluminium pole to make the extension and let the falling derrick sit on top of a supermarket crate rather than install a further vertical section to let it self-align. I’d still end up with a 9m long falling derrick, but it would be lighter and easier to construct.

What to do? Fortunately, Tom had recently read an IEEE article about adding elevated radials to AM broadcast stations that had disintegrating buried radial systems. One of the key points was that the new radials needed to be elevated, not the whole antenna. Actually, the radials can be lifted at an abrupt angle right at the antenna and then run horizontally. We left the vertical in place, but raised the radials around six feet. Immediately we were able to obtain a good match. We concluded that all radials at this location needed to be elevated due to the interaction with the very lossy ground. For the ARRL Contest, we elevated the 160m and 80m radials by around 6 feet, the 40m radials by four feet, and we left the 20m radials sloping from about a foot, down close to the ground. When we returned for the CQ WW CW Contest, we elevated all radials.

Mast e pre contest

mast e pre contest


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