[50mhz] Revised (v2.0) paper on Cushcraft A50-5S modification

[Bill VanAlstyne, W5WVO]

I've just revised my paper "Improving the Cushcraft A50-5S 6M Yagi with an
Extended Boom and Optimized Design" and posted it on the 6mt.com site
(http://www.6mt.com/A50-5S_w5wvo.pdf). Feedpoint matching has been fine-tuned
with an MFJ-259B analyzer, and the final driven-element and gamma match
dimensions have been included in the paper. As a test, the antenna was
disassembled, relocated, and then reassembled according to these new dimensions.
Mounted at a different height and fed with a different length of coax, the
antenna still showed a perfect 1:1 match at the design frequency after
reassembly. (Your mileage may vary.)

Many on this list downloaded the original version of this paper in 2003, but for
those of you who aren't familiar with it: The paper describes how to modify the
A50-5S 5-element yagi for 6 meters at extremely low cost. The results of the
modifcation are higher forward gain, a greatly improved pattern and F/B ratio,
and a tighter 3-dB beamwidth. All properties are fully characterized using
computer simulation, with before-and-after azimuth and elevation charts provided
(nominal 32-foot mount above level terrain).

New materials required to perform the modification:  a) one six-foot section of
1.5" 17-gauge aluminum tubing, available from Texas Towers for $11.70 plus
shipping, and  b) two stainless-steel hose clamps available at any hardware
store for about $1.50.  Hand tools required include assorted socket wrenches, a
tape measure, a hacksaw, screwdrivers, etc.

On-air results have been very gratifying. IMO, this is the cheapest way to get a
pretty darn good 6M antenna up on your tower or mast. Of course, if you already
have an A50-5S, or can get one cheap from another ham, this is a no-brainer. But
even buying new, it's a deal. Compare:

Cushcraft A50-5S + 6' aluminum tubing + hose clamps ==> approx $182.20 from
Texas Towers
M2 6M5X (design and specs very similar -- compare) ==> $219 from Texas Towers

No cost for my paper, of course. Download it and check it out! (Be patient -- 6m
t.com ain't the fastest website on the Net.) If you have any questions after
reading the paper, feel free to email me.

Bill / W5WVO
Rio Rancho, NM