Here are two plots showing the antenna pattern. I do not have a rotator - so while plotting I am manually rotating the antenna, trying to maintain an even speed while making one full revolution in 60 seconds. Not easy! This plot was made while listening to AM1600, a low power omni station 2 miles to my east, a clear shot across salt water.
The yellow is with the 160/80m antenna in the 80m position (detuning the antenna from 160m). The blue arc is in the 160m position. There seems to be little difference, with the exception of some lost F/B, however I notice the noise floor increase when listening on the RX antenna and switch the big vertical into resonance on Top Band. Also note the fatter lobes to the left quadrant. I have power lines running on this side of the antenna, perhaps 50ft away. Could this be the reason?
This seems to be a much prettier plot. This was taken while listening to AM1660, located due north of my some hundred miles away on the mainland in Naples, Florida. The difference is that I am looking directly into the power lines when pointed at this station. In my opinion, this confirms that the rear lobe seen on AM1600 is due to interaction with the power lines.
I replaced the CAT5 twisted pair at the point where the mast rotates in it’s mount. The other day, I left the antenna unpinned and it freewheeled in a thunder storm, breaking the CAT5 twisted pair. This beefy homemade twisted pair was made by cutting two equal lengths of wire, and spinning them with an electric drill with the opposite ends in a vice.
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This post was written by admin on October 4, 2009