Sunday, September 27, 2015

New Beam Antenna Installation at N6QW ~ FINAL INSTALLMENT!

The Final Piece - Post Mortem!

My dream beam is up and operating and I surely can tell the difference! The front to side and front to back attenuation is very evident and I have netted quite a few contacts running 100 watts with my ZIA transceiver on 20 Meters. The signal reports are very good even with crappy band conditions so all and all I am a happy camper.
The cost of this installation --well I stopped counting after $2300. The mast with accessories and delivery was close to $800. The beam with shipping was $500 and the rotator with free shipping was $300. The coax and rotator cables were $250. The US Tower base plate with shipping was about $100. The Home Depot hardware was $100 and the contractor was $200. That is a lot to spend for a beam that ostensibly will be used during the down part of the solar cycle. But given where I am age wise this is probably not  all a bad decision. For about another $1000 I probably could have had a 40 foot tower and a three element beam. But never look back.
Some lessons learned:
  1. The information from the manufacturers is not very good or not even present. SpiderBeam does not have an instruction manual! Given that I am bottom rotating the mast I was told very few are sold for this purpose especially in a fixed location installation thus no manual. I did receive good factory support when I asked about drilling the mast for the bottom mast to rotator adapter and how to route the coax from the beam -- however, this should be standard information and not require emails to the factory.
  2. Yaesu (I am using Model G450) has a standard calibration process for zeroing the rotator so when you are north the beam is actually pointing north. However there are several steps which are not clear and I had to call the factory -- and sort of got "Oh yeah we get calls about that all of the time." So I am not the only one.
  3. I purchased a Mosley custom beam the Model MP-32-N which has the high power driven element from a TA-32 and the lower power reflector from the TA-32- Jr. The instructions are for the most part are OK except for three items. 1) There is an anti-corrosion compound that must be applied to all metal to metal mechanically connected parts. The only place this is mentioned is on the pictorial assembly drawing. The actual assembly instructions about fit Tab A into Slot B are silent on this matter. So if I had not spotted the note on the pictorial drawing my install would have lacked the compound. 2) Routing of the coax from the beam. I called the factory and inquired about a choke balun. I was told that is a really good idea and was given the dimensions. So why is not this just standard practice to say build a choke balun? Actually using the balun facilitates routing of the coax. 3) Where to place the boom to mast bracket? The parts are color coded and one of the final instructions says align the boom to mast bracket with the black index marks on the boom. Mine didn't have such marks and so I called the factory and was told it should be in the middle at the balance point (36 inches). The word balance point rang my bell! The driven element is heavier given the larger traps and size of tubing. So the balance point has to be closer to the driven element. I used a crude mechanism to create a balance structure ( a couple of stacked  1 X1 "'s ) and moved the boom along the balance beam until I found the balance point --which is 28" from the driven element. So why isn't that information in the assembly instructions?
This will be the last post on my antenna and future posts will concentrate on the Simple-ceiver.
Thanks for riding along!
Pete N6QW


  1. Pete,
    It is awesome to see rotations and radio waves making their journey. At some point you will need to rotate that beam to Hawaii and get a contact with Aloha!

  2. Replies
    1. Hi John,
      Thanks for your note. The beam is working well and the only hitch so far is something I was told not to do and probably should have done. I inquired from the beam manufacturer about "pinning" the beam to the mast. I had done this with a prior beam installation from a different manufacturer. I was told "don't do it" --even though there are pre drilled holes in the boom to mast bracket. Mosley's reasoning was that since I was using a slender mast assembly that significant wind loading could "wind up" the mast like a corkscrew. In effect the larger structure of the beam permanently affixed to the mast would generate very large rotational forces on the mast and bottom mounted rotator. Here in Southern California we occasionally experience reverse winds from the desert to the sea known as Santa Ana winds. Shortly after the install we had that wind condition and now the beam is off by about 30 degrees from what is indicated on the rotator. I now have an idea of a fixture to enable me to loosen one of the couplings on the push up mast and thus readjust the beam to a zero condition. "There ain't no free lunches!"

      When I mentioned to Mosley this possibility of having to "re-zero" the beam by not pinning the beam to the mast--their response was --cheaper to realign the beam than to have to purchase a new mast-- they were probably correct.

      Pete N6QW


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