Quite to the contrary, I had this particular question just last week on a
Crunchcraft 13B2 installation, and I went right to the guy that designed it,
Joe W1JR, he specifically said that that particular antenna was designed to be
mounted either polarization, just keep the mast where they tell you to put the
bracket, and run the mast only into the bracket and not above it. He said the
degradation was in the tenth's of DB's, and was not noticeable.
Work me in the Mass QSO Party on May 1 and 2!
73,
Scott
KA1CLX
At 09:14 AM 4/12/99 -0500, you wrote:
>
>>I am installing a 2m yagi for local nets/emergency ops onto the top of
>>my stack and would like to mount it vertically for proper polarization,
>>but am wondering if the metal mast will interfere with it's properties?
>
>Guaranteed that it WILL.
>
>Years ago, I did just that very same thing... and used the 2M antenna
>(a 10L yagi) for about 4 years, but with only mediocre performance.
>Then, for some reason, I decided to off-center mount the yagi, to see
>if I WAS actually experiencing problems from the in-plane mast. I
>added a 3' long horizontal mast to the mast from the rotator, and then
>attached the 2M yagi about 2-1/2' out on the horizontal mast, the
>yagi was still oriented vertically. The difference in performance
>was astounding, probably 10dB OR MORE (as measured by a 2+ S-unit
>increase in received signal strengths). Note that at the same time
>as when I moved the yagi, I also moved the COAX out of the plane of
>the yagi elements as well.
>
>>Should I try to change over to a fiberglass mast above the beam or does
>>the polarization really matter with 2m after a short distance?
>
>Fiberglass works well, but it's probably easier, and possibly lower
>cost to just add another boom-to-mast mount (made of a 5" x 5" x 1/4"
>piece of aluminum plate and 4 U-bolts) and a short (3') horizontal
>mast, and side-mount the 2M antenna.
>
>This addition shouldn't materially unbalance your array, unless the
>2M antenna is really heavy.
>
>73,
>
>Tom Hammond N0SS
>
>73 - Tom Hammond N0SS
>
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