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Old 1-Jun-2015, 2:57 PM   #1
rickbb
Senior Member
 
Join Date: Dec 2014
Posts: 304
4 bay out performs 8 bays

Kind of a long post, I apologize for that.

http://www.tvfool.com/?option=com_wr...f1f063131b14c3

Spent a weekend experimenting with my reception dilemma. Used 2 mast locations and 3 variations of the Mclapp M4 and M8 antennas.

I tried 3 antennas, my current DIY M4 10 x 9.5, a new DIY vertical M8 10 x 9.5 and a “twisted” M8 10 x 9.5. All using Mclapp’s designs. I got the twisted design from a NEC simulation I found on a site from holl_ands. (The top 4 bow ties are aimed at 90 degrees to the bottom 4 bays to take advantage of the null zones of each 4 bay panel.)

I combined the 4 bays on the M8’s 3 different ways, one with dual baluns and a splitter reversed, one with identical lengths of 300 ohm feed line and single balun and one using instructions for co-phase lines for vertical M8's on Mclapp's web site.

I have the situation of having 3 main directions to receive from. 2 are almost 180 degrees apart so my DIY M4 gets both of those directions just fine. The third direction is almost 90 degrees apart from the others, and in the RF shadow of 2 large Maple trees in my front yard. Hence my problem and experiments.

I knew I needed a different location so I mounted a new 10 mast on the other side of the roof line, 16 feet west from the current mast point and 10 feet north. This would give me a clear shot around the trees to all broadcast directions. Height was about the same 25 ft. AGL.

The results? Reception was worse overall for all antennas at the new location. I got greatly improved signal from the SSE towers since I had cleared the trees from the line of sight. The towers from the west were the same as before, but the towers from the ESE were all way worse. A few even gone completely.

Tried all 3 antennas back at my original and current mounting point and signals were back to where they have been. The funny part is my M4 outperformed both versions of the M8 in both locations. I will go back over the construction of the 8 bays to make sure I haven’t made some mistakes in spacing, etc.

I wound up just putting my M4 back and adding 6 feet to my original mast height and improved signal quality from the east quite a bit. Signals from the south, behind the tree, are still dropping out on me. When the wind blows it’s so bad it’s unwatchable.

I have 2 more locations on the roof to try, I’m guessing that perfect looking spot wasn’t so perfect after all.
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