I had to lower my antenna prior to my trip to Honolulu last week, in case a storm popped up while I was off island. Now that I’m back, it was an ideal time to relocate the 40/30m dipole currently in a 35ft high coconut tree.
I placed an extension above the Spiderbeam to move the dipole out of the tree and to get it up a bit higher. Some trig was necessary to figure out how high the extension needed to be so the near end of the dipole would clear the tip of the yagi.
The extension is not affixed to the mast, allowing it to rotate. In addition, the dipole is not pulled all the way up to the pulley so the yagi can still be rotated and not break the fixed dipole. The 8″ or so of line between the pulley and the antenna feed point allows the line to wrap around the mast when it rotates. In addition, the top 12″ or so of the extension is insulated so the dipole won’t short out to the mast should they make contact.
With this modification, I am done with 40-10m. There is really nothing more I can do which my current quarters, and the mast is at it’s limit. Any higher or bigger and I would not be able to raise and lower it by myself. The while assembly is very sturdy, and doesn’t move at all in the wind. The only time the winds exceed 20 or 30mph is during a tropical system, and everything will be lowered and secured before that happens.
The yagi (heavy duty Spiderbeam for 20/17/15/12/10m) is at 10.4 meters (34ft) and the center of the dipole is at 14.6 meters (48ft). The dipole worked well on both 40 and 30 when it was lower, so I expect performance to remain the same or increase a bit. I have some concern of interaction between 15 and 40, but no degradation has been noticed on 15m.
Time to make some QSOs, and to continue working on the 80/160m antenna!Start Slide Show with PicLens Lite
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This post was written by admin on July 31, 2010