[amsat-bb] Re: 70cm yagi design
mat_62 at netcommander.com
Thu Dec 27 17:07:36 PST 2007
I second this. These antennas are easy to construct and there is no
matching section to fiddle with. You can also construct a pair offset on
one boom for RHCP or LHCP, even switchable just like any other satellite
yagi but then you have to start dealing with phasing harnesses. I don't
have an SWR analyzer for that task so I've just got 11 elements and 4
elements vertically polarized on 70cm and 2 meters respectively. They
worked quite well when I had a rig! I'm trying now to find one I can
afford so I can get back in the game. I miss it!
James Duffey wrote:
> The Cheap Yagis by WA5VJB work great and are easy to make:
> < http://wa5vjb.com/yagi-pdf/cheapyagi.pdf >
> < http://www.wa5vjb.com/references/Cheap%20Antennas-LEOs.pdf >
> Precise measurements of element length at 432 are important. You
> should strive for measurements of at least +/-1/16" with +/- 1/32"
> better. For the metric inclined you should strive for +/- a mm. These
> tolerances are possible with a good metal rule, but a bit more
> difficult with a wooden rule or tape measure. Cut the element a bit
> long and then file or grind to the proper length checking often.
> I have made the 3, 4, and 6 element 2M versions and the 11 element
> 432 version. They all work well with sharp patterns. They have close
> to 50 Ohm impedance without adjustment. Let me know if you have any
> more questions, and more importantly, let us know how it all turns
> out. - Dr. Megacycle KK6MC/5
> James Duffey KK6MC/5
> Cedar Crest NM 87008
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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