Melvin G. Brafford wrote:
>
> Next week I hope to get my first 105BA 5 element 10 meter beam up to 92' on
> my WELL GUYED rohn 25G. My plan is to put another 105BA at the 62' level
> and a third one at 32'. The one on top will be rotatible , but the other
> two will have to be fixed for now. I plan to use a Dunestar stacking box to
> feed the three ants, and run various combinations of stacking. The land
> where this tower is sitting slopes steeply down to the NE and E, Making the
> top ant seem about 150', so with this in mind I had planned to fix ant
> 2..the one at 62' at 90
> (due East) degrees to pick up Africa and ant 3 the one at 32' NE or 45
> degrees to maximize Europe. I realize my big money run route will be
> Europe, so should I fix both antennas on EU, And use the Upper ant alone
> for Africa then stack all three for europe?
> Further, on tower #1 which is about 120' NW of the 92 footer, I am using a
> TH7 at 77', which is a band opener to the WEST. Also on this tower is
> another 105BAS at 38' fixed on the Carib. When the band is open this ant is
> hot, but in off years the TH7 beats it.My path to JA is unknown from this
> QTH, as it is new, post sunspots, ...hi....,but you can see forever in that
> direction from the tower.
> Wonder if I should stack another 105 on tower #1 fixed on JA at about 47'.
> then with a dunestar on that tower, I could stack the TH7 with it, and also
> stack the TH7 with the Carib/ South antenna when needed in that direction.
> Any suggestions would be appreciated.
> 73, Mick...W4YV
>
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Hi Mick!
I don't have all the answers to your questions, but I have a couple
suggestions.
First of all do not install the 105BA(S) antennas without modifying them
to be 105CA(S) antennas. The 105CA design has been computer optimized
and you will greatly appreciate the several dB gain and front to back
you will get after installing them as CA rather than BA. The difference
is mainly in the spacing of the elements on the boom. Just call HiGain
and buy the manual for the 105CA. You will be pleasently surprised how
easy it is to modify and how much difference it will make.
Secondly, I'd suggest you obtain a copy of EZNEC, YO, AO, or ELNEC and
model your antenna possibilities and see what results. That will give
you the numerical answers to input into your evaluation and hense, your
decision.
Third, I'd look at W6QHS' book at the imrovements in mechanical strength
he suggests for the 105BA(CA). With that many 105s, you might consider
reinforcing them if your location has high winds. W6QHS' book, The
Physical Design of Yagi Antennas, is worth buying and reading even if
you don't plan to reinforce the antennas. I have reinforced my yagis
per Dave's book (two 40-2CDs, 115CA, 205CA) and will reinforce the
105CA, 115CA and 205CA that will go up next year, also..
If you have any questions on the above, I'll be glad to answer them.
Bill, N3RR
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: K7LXC@contesting.com
Sponsored by Akorn Access, Inc & KM9P
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