Thanks James.
Yes that is the way I layed them out--using a long rule. I'm an old gage designer so understand cumulative error stackup.
Those are the same differences I have, but when the chart is used for the next two elements for a ten element unit, the spacings just look odd.
I'm going to build it as specified. It is that way on several pages so probably OK.
Now I just thave to get a 300.00 antenna analyzer to figure out if the match is good on the $10.00 antenna!! ;)
Curt
James Duffey wrote:
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
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-- KK6MC James Duffey Cedar Crest NM