Saturday, August 1, 2015

Building a new antenna at N6QW ~ Part VI

Additional evaluation of the H950 Mast

In the dark ages (over 50 years ago) while I was in high school taking the mandatory second year of Latin studies, I can well remember telling Miss Bushnell (the spinster Latin teacher) about how useless Latin was as a language and once the class was over would never use it in my lifetime. Miss Bushnell must be really smirking these days (hopefully from heaven)  as I attempt to use Roman (Latin) Numerals to order my blog posts. This says much for the old adage "Never Say Never!" I better end this thread soon as I am not sure what comes after X (Arabic 10).
Along the way I did learn about the "24 Hour Rule". Sometimes it is best to wait at least 24 Hours before making any important  decisions. Hopefully such a passing of time removes some of the emotionalism from the decision and adds a strong measure of logic to the mix.
The Never Say Never and 24 Hour Rule factors have caused me to rethink some of the concerns I have about the H950 push up mast and to come up with an alternate plan for the support mast and installation process.
  • My original plan was to remove the small concrete base that is now supporting the fiberglass mast. If that is removed and the H950 mast installation is a failure then I now have a problem of having No Antenna while I further resolve an alternate mast solution. Much effort went into finding dead center of the current base and the house bracket alignment. I might not be so lucky with the H950 and thus an additional concern.
  • I do my best thinking while I sleep and last night, while I slept, it came to me. Why not use the current base as a part of the H950 Mast install. In it current condition the concrete base having just a stub can serve as a temporary the base for the H950 (sans the clevis assembly). Now the H950 can be slipped over the stub and then affixed to the existing bracket assembly. At this point the mast only weighs about 34 pounds and this can be done without any extra hands or equipment. 
  • This achieves two purposes: 1) I can hand raise the H950 mast and get a better feel for its mechanical rigidity and 2) when raised to 27 feet allows the determination of the guying lengths and to evaluate the impact of the guys. The real bonus is that it preserves the original base assembly so that if necessary the current fiberglass antenna mast can be put back in place fairly easily.
  • Since I must wait a month for the beam to arrive, if this temporary H950 install works then I have the option of using the 20 Meter EDZ antenna with the Rohn mast and that will also be a part of the additional guying.
  • My brain while it was working on the problem, also came up with a way to pour the new base around the existing base so the clevis assembly can be refitted to the mast and the new concrete poured around the existing base with the mast installed. This will allow straight and true alignment of the mast.
  • In sum these new thoughts about the H950 enable me to make a measured evaluation of the H950 mast. Assuming this works the mast would be "pushed up" in place using some hired help to assist with that task.
  • I  also looked at the spider beam mast and concluded that I would be spending an additional $450 to essentially have the same concerns regarding rigidity and the erection process
We now have a plan for further evaluating the H950 that enables me to have hard data on its suitability while providing an option to go back to the fiberglass mast.
Stay tuned de N6QW.
(You are not going to believe this but our beloved "de" comes from the Latin meaning from --Miss Bushnell how did you know?)


  1. Pete, have you considered putting the rotator at the bottom of the mast to reduce the top weight considerably? I have a pole on the side of my garage that is about 20 ft high for my 6m beam, just a 2" Al scaffold pole with and 1.5" Al pole inside it. Top bracket has a bit of PVC pipe as a bearing, and bottom bracket holds a short piece of pipe holding the rotator above it. No guys for the small beam. Not too heavy to erect myself. It could be scaled up with your mast, adding guys on rotatable rings. No doubt it would be much easier to handle than having a heavy rotator at the top. Just a thought. 73 David GM4JJJ.

  2. Hi Dave,

    Thanks for the input. The rotator weighs around 7 pounds -- about a third of the weight of the beam so a bottom mount would be significant weight reduction. I have a Chimney at the back of the house and if I did something clever such as have a structure built so that the rotor is about 8 feet above ground then a mast 22 feet long would get me to 30 feet and the chimney at say the 13 foot level would have the house bracket assembly. Then one set of guys should do the rest. I may be able to use sections 2, 3 and 4 of the H950 Mast and eliminate the 1st and 5th section. You idea has a lot of merit.

    Thanks again --lots more "noodling".



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