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Rodger,
I have a DB-228 that is mounted in the center of the Northwest face. The faces are 8’ across if memory serves me correctly. We are at 635’ Center of Radiation and only running 12.5 watts in to the cavities but we are getting 45 – 50 mile radius coverage from the repeater. I have not noticed any REALLY bad nulls any were in the coverage pattern. I say that but I have also not done a commercial style drive on the repeater either. I really did not see it necessarily at the time but may do one at a later date. When the antenna was mounted, we turned the top four dipoles away from the tower and the bottom four dipoles to the tower. I know that you asked about a DB-224 and not a 228 but maybe this information will help a little bit. The antenna is only sitting 24” off of the face, and you said that you would be mounting off of a leg. Do you know how far off of the leg you are going to be able to get? If you are going to be less that 2” – 3” I would turn all of the dipoles in to the tower leg. If you can get 4” or more away from the tower I would point each one of the dipoles 90 degrees apart staring at the top and working you way down clockwise.
Hope this helps.
james//
-----Original Message-----
Monday, I am having this antenna put up on a triangular tower, whose face is greater than 20 ft. across where the antenna is going on one leg. I know from years of operation on this tower (or any tower that is this large), the antenna pattern will have many nulls around the tower. Does anyone have any experience on mounting an antenna on a large tower to minimize the nulls? The antenna will be mounted on a leg (not in the center of the face which may be more preferably). I have the choice of placing the dipoles equally around the antenna mast, all facing the tower or all facing away from the tower. Any suggestions (or does it really matter on a tower of this size)?
Roger W5RD
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- RE: [Repeater-Builder] dB224 4 bay 220 MHz Antenna on VERY LA... JamesMNelson
