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Foxracing
Intermediate Member
Username: Foxracing
Post Number: 107
Registered: 11-2003
| | Posted on Saturday, April 24, 2004 - 1:32 pm: | 
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A-99 and BIGSTICK
I have a tree where my antenna is in now and my 3 section A-99 is up there in the tree by at least 60-65ft and i have another tree about 50ft away from the one where my antenna is if i were to put up a big stick instead of another A-99 and co-phased them both together would this help my recieve or transmitt.I would like to know if you guys or gals explan the possitive and negative points to this.
THANKS
(GREG)
FOX--CEF 234 |
Tech808
Moderator
Username: Tech808
Post Number: 2226
Registered: 8-2002
| | Posted on Saturday, April 24, 2004 - 2:35 pm: |
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Foxracing,
Tech 833 answered this question for you in your other post in the Open Section.
Lon
Tech808 |
Kc0gxz
Advanced Member
Username: Kc0gxz
Post Number: 774
Registered: 3-2003
| | Posted on Saturday, April 24, 2004 - 10:33 pm: |
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Foxracing
If you are going to co-phase, do it with identical antennas.
Jeff, kc0gxz. |
Bullet
Intermediate Member
Username: Bullet
Post Number: 331
Registered: 7-2003
| | Posted on Tuesday, April 27, 2004 - 8:57 pm: |
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i will add this just because ive heard guys talking about co phasing alot.
when you co phase beams they need to be set up as close to the same as you can possibly get and mounted in the same fashion.
example if your gama rod is on top for vert and to the right side for horz the other beam should face in the exact same fashion on top and to the right. i hear alot of guys that mount them opposite of each other, buy the book this is incorrect.
also they need to be set far enuff apart to reach the full effect of the co phaseing potential of 3 db closer spacings will yield less gain. PERIOD!
the makers of the moon raker sugests 24 feet.
not saying they wont work at 18 feet cause they surly will but your not getting all the gain from stacking that you went to all the trouble to get.
and the phasing harness should be made of "odd" 1/4 "electrical wavelenth" multiples of either 75 or 96 ohm coax.and held to exactly the same lenght for each side and conected with a t conector. your 50 ohm of coarse hooks to the open end of the t.
my 2 cent on co phasing. |
Kc0gxz
Advanced Member
Username: Kc0gxz
Post Number: 779
Registered: 3-2003
| | Posted on Thursday, April 29, 2004 - 2:48 pm: |
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Very informative post, Bullet. Good work.
I've done a lot of tower climbing and installed quite a few beams in my time but never did any stacking work.
Jeff.
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Bullet
Intermediate Member
Username: Bullet
Post Number: 333
Registered: 7-2003
| | Posted on Thursday, May 06, 2004 - 8:33 pm: |
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id rather use a bigger single beam than stack them. to much trouble,(not as gung ho as i used to be) unless youve just got the bug for it!
alot of times you can build you a long beam thats very close to what youd have from a pair of small beams.
a fella i know is stacking a pair of Sig.Eng 4's
and stacking them at about 28 feet apart using a monster boom and guy system. "awesome project".
now i figure these to be in the neighborhood of about 10 dbd for the lightning 4 with the 15 ft boom.
and if you can yeild a perfect 3db from stacking them that would put the array in the 13 dbd range.
if one was to lengthen the boom using maximum spacings for gain on all the directors and optimized the spacing for gain/ftb for the reflector/driven element,and remade the wire elements on all elements, using optimized figures for gain
one would have a single beam that i feel could compete with a stacked pair. though it would be about twice the length of the s.e lightning 4's.
optimized element lengths alone can yeild 1 db of gain over standard fig.and optimized gain spacings can yield up to 2+ db.
so i think this puts you pretty close. coarse comparitively its all just on paper!
we live about 1 hour apart so side by side comparisons will not be a realistic task.
i cant wait to hear his stacked S.E Quads on the air but id really love to do some field strength readings on them and compare them to my 4 element optimized quad.(size of a laser 400)
i have compared feild strength readings between my long 4 element and a 34 foot 6 elem quad i built.
and interestingly the 4 element showed a good deal more forward power than the 6 did.
but the six had better side/rear rejection, a parameter that the beam was built for.
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