At 12:21 AM 8/9/2007, Cqtestk4xs@aol.com wrote:
>I have finally moved into my new home in KH6 and will be getting the
>building of the station underway in the next month or so.
>
>I am limited to one tower for ham radio but the rules say nothing about
>putting up a vertical of a "non-tower"....pole.
>
>Here's the story. I want a cheap, tough (lots of brisk,steady tradewinds)
>vertical that covers 40 through 10 meters. Plans are to mount it at roof
>level (next to the metal roof which measures 45 by 48 at about
>20 feet height) to
>take advantage of my metal roof as a ground plane. However, I plan on
>running radials on the sides of the antenna not covered by the
>metal roof. No, I
>can't mount the antenna on the roof.
>
>Any suggestions for which vertical which fits the criteria above?
How much power, and can you run an autotuner?
How much construction are you willing to do?
If it were me, I'd put up a straight pole of some sort and a SGC
tuner at the base. Length isn't critical as long as you stay away
from something that's "bad" (i.e. an exact half wavelength on a
frequency you want to operate on).
Another choice is the SteppIR vertical.
Another choice is something like a trapped vertical. The pattern
will be slightly different (depending on the lengths and frequency
ranges).. the single long rod, at high frequencies where you get much
more than 1/2 wavelength, will have more funny lobes and such, while
the trapped vertical is essentially shorter at higher frequencies,
and so, the pattern looks more like the classic 1/4wave vertical on
all bands.
Another choice is a fixed rod, and a relay selected tuning network at
the base (or a switched network in the middle).
A final choice is some sort of home brew multi band vertical (several
wires straight and spiraled on a core) but tuning is a nightmare if
you want to run "tunerless".
With the trapped antenna, there's some non-zero (but probably small)
loss in the traps.
With the steppIR, you've got to wait for it to readjust on band changes.
With the SGC tuner, you've got some small loss in the tuner.
With the switched base network, you've got some designing and
building to do, but the losses could potentially be lower than with
the SGC. (Although, the loss in the SGC is pretty low, especially on
the big one.. can't have 10% loss running a kilowatt without melting
the insides)
Jim,w6rmk
>
>Thanks.
>
>Bill KH7XS/K4XS
>
>
>
>************************************** Get a sneak peek of the all-new AOL at
>http://discover.aol.com/memed/aolcom30tour
>_______________________________________________
>
>
>
>_______________________________________________
>TowerTalk mailing list
>TowerTalk@contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|