Körner FM 19.3-40 Yagi
My near neighbour Paul has kindly adapted my Körner 19.3 beam to the newer 19.3-40 with enhanced F/B ratio.
The boom has been increased to 5.7M long and dipole spacing has been increased to reduce side lobes, but the main objective was to improve F/B ratio which has been achieved with minimal reduction in gain at the low end and no decrease further up.
The redesigned reflector array meant it was easier to just extend the boom at the rear end to attach the centre reflector. That plus the front extension allowed me to keep both the vertical elements and support chord in the original locations. This maintained the original balance point for the mounting bracket. The dipole was made from the same 1/2" tubing as the elements to save compromising the performance by using flat bar in the construction. Connection is via a half wave coaxial balun.
The new design, combined with the TGN ULNA 3018 Mk.IV Band 2 masthead preamp, could be a very interesting combination in the days and weeks ahead.
Here are plots showing the 19.3 and the 19.3-40 and some photographs.
Click on thumbnails to enlarge
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