Finalizing the Antenna Plans…
By jimrob | February 2, 2007
Okay, I belive I have finally reached the point where I can start constructing the antenna/tower setup, weather permitting.
We (the wife and I) have decided to forgo a tower for now. We don’t plan on living here forever (at this point, anyway) and spending the kilo-bucks on a tower installation would be wasteful.
Instead, I’ve decided to go with my 10′ roof tower on the 14′ roof of my garage. Combined with a 10′ TV mast, this will put my Cushcraft tri-bander at around thirty feet. I will also mount my 2m SSB beam on the mast.
For additional support, an inexpensive thrust bearing will be mounted a foot or so below the beam, and guyed to either the garage roof or the tower itself. To this (after seeing how bad it rotates with the mast….) an inverted vee will be mounted, most likely a 40m vee.
For the low bands, I will build a vertical when funds are available. I’ve been studying the design lately, and have been intrigued by a 55′ 160/80/40 vertical built by Jerry, K5OE. Given current aluminum prices, I estimated construction costs to be somewhere in the neighborhood of three-hundred dollars.
I looked into ground-mounted verticals, but for multi-band operation I will need to bury radials. To get the “required” 36 verticals for decent 160m operation, I’d have to bury almost 4,000 feet of wire in my yard. That ain’t gonna happen.
If I could get by with single-band operation, I could construct a 1/2wl vertical. If I were to build such an antenna for 40m, I could add 36 radials of approximately 66 foot length (from my understanding of the subject) and use it as a 1/4wl vertical on 80m. That leaves me without a desired band, 160m.
Another problem with radials is the space-crunch they will present when planning my garden. Add to that the call-before-you-dig regulations, the phone cables running somewhere in that part of the property, and I’ve turned my weekend antenna build into a regulatory mess.
Also, an elevated vertical will keep another problem from arising - accidentally electrocuting the numb-nut kid who cuts through my yard in the night to screw the teenage girl across the street. Ugh.
Another posibility I’ve considered is mounting my 2m FM Ringo Ranger atop my HF vertical. I’ve yet to discover how the two would interact. Making the Ringo part of the vertical would be neat, but would require filter design which is (at this stage of my engineering education) over my head. Most likely, I will isolate the Ringo from the vertical with a section of PVC pipe, then run the coax feed down the center of the HF vertical. Should this not work, I’ll probably just throw the ringo on the side of the roof tower. I only use it for cross-town talking anyway. (And in a town of 5,000 people, you don’t need much.)
Construction will have to wait until spring, of course. Ground rods will need to be driven, new wire laid to the shack, a wall built for the shack, blackjack put on the roof around the tower base…
Any hams in the southeast Iowa area wanna help me figure out how to get a roof tower with 10′ of pipe and a tri-band beam up on the roof?
Topics: Antennas |
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