[amsat-bb] Re: Question re WA5VJB "Cheap Yagiis"

[James Duffey]

Curt - I have built lots of there. I use the 1/2 inch as the inside  
dimension.

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  
> last
> directors in both the 435 and 432 versions.  The spacing increments  
> seem
> 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??
>
> Thanks,
>
> Curt
>
> KU8L
>
>
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the  
> author.
> Not an AMSAT-NA member? Join now to support the amateur satellite  
> program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

--
KK6MC
James Duffey
Cedar Crest NM