HY GAIN VB66-DX 6M YAGI

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magoo41
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Joined: Sun Jun 07, 2020 7:52 pm

HY GAIN VB66-DX 6M YAGI

Post by magoo41 » Sun Jun 07, 2020 9:17 pm

I recently acquired this model and discovered that the point of lowest SWR using the values in the manual was 1.4:1 at 50,880 when it should have been 1.1:1 at 50.100 or so. This was with the beam standing up not quite vertical with the reflector on the ground, the same position I have used over the years to tune up many yagi antennas. After playing around for some time I have found that the length of each half DE needs to be 56 5/8" and not 55 7/8". In addition, dimension B on the beta match should be 13" and not 11". There was some discussion a few years ago about the diameter of the beta tube and the DE elements furnished after MFJ took over Hy Gain; apparently they had previously been 5/8" whereas those furnished with the beam today are 7/16". IMHO, this change in diameter would certainly affect the required length of the DE elements and probably affect dimension B to some extent as well.

After working away at the problem the point of lowest SWR rested at 50.560 with an R of 47 ohms and a 1:1 reading. SWR rose to 1.25 at 50.05 and 51.150. This suits me fine....it is not perfect though!

Bill VE3NH

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