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Old July 6th 04, 03:46 AM
Dustin
 
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Default 2 Meter Beam 4 element design wanted

hello, I am looking for a 2 Meter 4 element beam design, preferably for a 4
foot boom, because I have an 2M antenna right now, but it's not configured
for 144.200 like I want to use if for, the elements are too short, and I
wanted to basically know if the spacing is correct for 144.200 or would I
have to change that along with the element length. the frequency of the
antenna now is approx. 165.00. Thank you very much.

KC8ZEM



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Old July 6th 04, 05:15 AM
Howard
 
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On Mon, 5 Jul 2004 22:46:32 -0400, "Dustin"
wrote:

hello, I am looking for a 2 Meter 4 element beam design, preferably for a 4
foot boom, because I have an 2M antenna right now, but it's not configured
for 144.200 like I want to use if for, the elements are too short, and I
wanted to basically know if the spacing is correct for 144.200 or would I
have to change that along with the element length. the frequency of the
antenna now is approx. 165.00. Thank you very much.

KC8ZEM


Dustin,
As a Michigander (relocated to California 24 years ago from the Bay
City area) allow me to offer some assistance. If you want something
'on the cheap' the following site has just what you need - yagi's
built with wood & wi http://www.clarc.org/Articles/uhf.htm

If you are willing to look at other options here's a Moxon rectangle
that will give 10.71 dBi and though designed for 146 it could scale to
144 with minimal difficulty: http://www.cebik.com/moxbld.html

Are you married to the idea of a 4' beam or are you willing to go
longer? A longer boom (and a few more elements) will improve your
range; if your'e willing here's another wood & wire antenna called a
Quagi that works nicely. I did an 8 element UHF version and made
contact over a distance of 126 miles using 5 watts - of course more
power made me more readable but the point is more boom = greater range
(as a general rule of thumb):
http://commfaculty.fullerton.edu/woverbeck/quagi.htm

On your existing yagi did you mean to say it's tuned for 145.00? If
so then just play with the feed to get a decent VSWR and change it to
horizontal polarization and you're ready to rock. I've used a
Cushcraft 4 element beam that was tuned for 146 and the VSWR at 144.2
was close to 3:1 and the polarization was wrong - it was taken down
and replaced with a nice M2 7 element. I do however still have the
instructions for the Cuschcraft and if you'd like to use them as a
guide to building something let me know and I'll scan them & send them
to you. The difference in tuning it is where you place the shorting
bars on the T-match and requires no change of element length or
spacing.

Hope this helps & let me know if you're interested in the Cushcraft
instructions.

73,
Howard KE6MAK


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