[amsat-bb] Re: Question re WA5VJB "Cheap Yagiis"
JamesDuffey at comcast.net
Fri Nov 14 16:52:45 PST 2008
Curt - I have built lots of there. I use the 1/2 inch as the inside
It is best to measure the spacing as cumulative from the rear, not
incremental. That eliminates cumulative errors. ANd you don't have to
subtract. Use a tape measure, or you can buy a 5 or 6 ft steel rule
pretty cheaply at Lowes or HOme Depot.
Here is the referencce I use for LEO antennas:
< http://www.wa5vjb.com/references/Cheap%20Antennas-LEOs.pdf >
Here is what I get for the spacings when I subtract: 5.75, 6.25, 6.5,
6.5, 7.25. I think that this is reasonable.
But don't subtract measure it all from a single reference point, the
reflector. The antennas work great. - Duffey
On Nov 14, 2008, at 11:47 AM, Curt Nixon wrote:
> Good afternoon:
> Hi have liked the way the WA5VJB Kent Britain 144Mhz cheap yagi worked
> so decided to build one for 435.
> Couple of questions:
> For the driven element "hairpin" or J, it shows 1/2" dimension for the
> spacing--knowing this might be critical on 435, is that INSIDE spacing
> or OUTSIDE spacing??
> Also, I noticed what appears to be unusual element spacing for the
> directors in both the 435 and 432 versions. The spacing increments
> to follow an increasing spacing trend but then the last couple are
> different. ie spacing goes ...6.25, 6.5, 6.5, 7.25, 7.25, 7.0,
> then 7.5.
> Is this a result of the computer design for easily progressive
> build, or
> perhaps some error in the dimensions posted on-line??
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Cedar Crest NM
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