Thursday, September 3, 2015

New Beam Antenna Build at N6QW ~ Part 12

More Preparations for the Installation

Houston: We have Rotation!
 Hopefully I won't be boring the readers much longer with this, what I now believe. was somewhat of an insane project. Much is happening in the background in preparation for the final erection of the beam on the mast and the hoisting of the mast into the air. There are just so many details that must be in place and anyone who tells you their accomplishment of a similar project was done in one day must be awfully lucky or that the install will not last the winter!
Here are some of the tasks which have been going on in preparation for the final installation.
  • The key issue is that the rotator must be capable of bottom rotating the mast and to do this properly requires having the rotator in a level position. A bit of rework was required to have that occur and luckily my idea of having the threaded portion of the anchor bolts be sufficiently long so as to accommodate a nut and washer underneath the L bracket assembly plus a nut on the top portion of the L bracket to secure the US Tower RP-3 to the anchor bolts. The bottom nut plus washer acts as a jack screw and a level placed on the three corners of the RP-3 must indicate being level at those three points. It took a bit of juggling amongst the three location but the RP-3 is now flat level!
  • The rotator itself must be calibrated so that when the indicator points north the beam is pointing north ( 0 Degrees)  and when you perform a full rotation the beam is pointing north (360 Degrees). The instructions are a little confusing but a call to Yaesu confirmed I was not crazy and so that part is done. Yaesu's instructions were adamant -- do this process on the bench as it took a while and the last thing you want to do is climb a tower to get this done. Luckily with a bottom mount not so much of a problem.
  • The SpiderBeam Mast is intended to be rotated from the bottom and to keep the mast vertical two sets of guying rings and wires are used to make that happen. I just did not feel comfortable that this would be easily done! So my plan was to fabricate a sleeved  bearing assembly that would capture the mast at about the 8 foot level to provide an additional vertical guide to the mast during rotation and to take up any side loading from wind acting on the beam/mast. The final configuration consists of a house bracket mounted to the eaves of my home and a two piece saddle assembly formed by a piece of 2X4 which was hand cut to be slightly larger in diameter than the mast and covers about half of the diameter of the mast section. The second piece of the bearing is made from conduit clamp material that is then screwed into the 2X4. The conduit clamp is wrapped with vinyl tape so it doe not abrade the metal mast. The 2X4 portion of the saddle is painted with epoxy paint. Luckily a piece of 2.5" PVC pipe union is about the outside diameter of the mast section at the bracket location. So this union served as a template of how much of the 2x4 needed to be carved out to capture the mast and this is shown below.

  • The Mosley 2 element beam arrived yesterday and weighs about 18 pounds. It has not been assembled as yet but I can see already some issue with raising the beam and the mast as it get higher in the air and my ability to push up the mast to the 30 foot level as a one man job. I will also have to address the beam to mast assembly so that the beam does freewheel on the mast and will require some sort of pin anchor.
    Having completed the house bracket and assuring my self that the mast section when placed in the bracket would be in a true vertical position I temporarily installed the mast in the rotator and after having calibrated the G450, the temptation to try several cycle of rotation was just too great!  Houston: We have Rotation! 

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