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<DIV><!-- Converted from text/plain format --><FONT face=Tahoma>A couple of
weeks ago I inquired with Tom Charles, the owner of Gizmotchy and Maco Antennas,
about his 2 meter, 4 element Gizmotchy beam. The Gizmotchy is interesting to me
because it has the ability to be used either with vertical or horizontal
polarization,<I> or both </I>(not at the same time) with the right setup. I told
him I was interested in buying one for my own station and would probably end up
writing a review on the antenna if I did so. I was was asking what test
documentation he might already have for the antenna. He very graciously offered
to send me an antenna for free to try out.<BR><BR>I received the antenna very
quickly, but had to wait for the weather to clear up to start the assembly. I
also had to gather a few other pieces of the antenna system necessary to use the
Gizmotchy effectively. Weather in Southern California was nice this weekend, so
I was able to make a little progress on getting the antenna up in the
air.<BR><BR>Here is a pic of the antenna as it is delivered, once you take it
out of the box:<BR><BR><IMG alt=""
src="http://www.worldwidedx.com/members/moleculo-albums-gizmotchy-2-meter-4-element-beam-picture1756-all-parts-beam-laid-out.jpg"
border=0><BR><BR>I don't know what gauge aluminum tubing is used, but I can tell
you that it is heavy-duty for an antenna of this size.<BR><BR>This is a picture
of the hub used to assemble the elements.<BR><BR><IMG alt=""
src="http://www.worldwidedx.com/members/moleculo-albums-gizmotchy-2-meter-4-element-beam-picture1757-hub-elements.jpg"
border=0><BR><BR>The mounts for the actual element pieces are solid aluminum and
are attached to the center ring by pressing them into a drilled hole. They are
then held into place by a roll pin that has been pressed in. The inside of the
hub looks like it is then machined for a perfect, smooth fit. The hub shown in
the above picture is for the driven element; it is the only one with additional
tapped machine screw holes.<BR><BR>The hubs are slid over the boom and held into
place by thumb screws. Here is a picture of a the mounted driven element
hub:<BR><BR><IMG alt=""
src="http://www.worldwidedx.com/members/moleculo-albums-gizmotchy-2-meter-4-element-beam-picture1758-hub-installed-gamma-matches-attach-one.jpg"
border=0><BR><BR>This picture shows the boom with all of the hubs
assembled:<BR><BR><IMG alt=""
src="http://www.worldwidedx.com/members/moleculo-albums-gizmotchy-2-meter-4-element-beam-picture1759-hubs-measured-installed-boom.jpg"
border=0><BR><BR>This is a good place for my first improvement suggestion for
this antenna. The manual gives you the spacing measurements for the elements.
You must measure and place them yourself, which is no big deal. However, since
there is no need to adjust the spacing, it would be very helpful if the boom was
already marked for you. But I'll take it one step better than that: Later on in
the installation, you are going to want to make sure that all of the elements
are aligned as straight as possible. However, when tightening the thumb screws
on the hubs, it causes the whole element to turn slightly. If the boom was
pre-drilled and tapped for the thumb screws on the hubs, the user would not have
to measure, and they also wouldn't have to align the orientation of the elements
manually. A pre-drilled and tapped boom would also make the the element assembly
even stronger. I would think that this improvement would be simple to implement
and add very little cost to the manufacturing process, but it would be a huge
win for the consumer.<BR><BR>As I mentioned before, the Gizmotchy antenna is
interesting because it can be used with vertical or horizontal polarization.
This dual purpose polarization is achieved by two gamma matches.<BR><BR>These
are the main gamma match stubs for each section. The one with the plug is for
the vertical elements to keep the water out. The hose clamps make them
adjustable for tuning.<BR><BR><IMG alt=""
src="http://www.worldwidedx.com/members/moleculo-albums-gizmotchy-2-meter-4-element-beam-picture1760-2-gamma-matches-plastic-capped-one-vertical-one.jpg"
border=0><BR><BR>Here are the gamma match tuning sections fully
assembled:<BR><BR><IMG alt=""
src="http://www.worldwidedx.com/members/moleculo-albums-gizmotchy-2-meter-4-element-beam-picture1761-gamma-matches-installed.jpg"
border=0><BR><BR>Notice that there are two SO-239 connectors. If you want to use
the antenna for both vertical or horizontal polarization, you must use two feed
lines to the antenna. In this picture, you see the boom and driven elements
mostly assembled. However, this is where I ran into my first problem: Notice the
L bracket in the picture that attaches the boom to the mast. Well, I couldn't
mount the U-bolts to this L-bracket as it was delivered from the factory because
the holes in the bracket didn't align with the U-Bolts. I couldn't get any of
the U-Bolts for the boom or mast through the mounting holes in this bracket
because the holes in the bracket were narrower than the U-Bolts. I used a rat
tail file on the holes to widen them and make it possible to mount U-Bolts in
the boom and mast bracket holes.<BR><BR>Here is a close-up picture of the
assembled, not-tuned gamma match: <IMG alt=""
src="http://www.worldwidedx.com/members/moleculo-albums-gizmotchy-2-meter-4-element-beam-picture1762-close-up-gamma-match-assembly.jpg"
border=0><BR><BR>It should be noted that the gamma match assemblies do not come
pre-measured for best match. I wanted to see where they were out of the box, so
I just attached everything together for some measurements down the road. This is
also where I encountered my second problem with the antenna assembly: The
package was missing one of the small bolts necessary to assemble one of the
gamma matches. When you open each of the bags of parts, you'll see a sticker
indicating that the bag has been weighed for accuracy. Well, the hardware bag
that I received was short one bolt but had one extra nut, which is probably why
it weighed out OK. It wasn't a big deal because I had some extra hardware that
kept the antenna assembly going.<BR><BR>While I was looking through my bin of
nuts and bolts for compatible parts, I decided to give one of the supplied
Gizmotchy antenna machine screws a magnet test to verify that it was stainless
steel. To my surprise, I found that it was not stainless steel (stainless steel
is not magnetic). The supplied machine screws and nuts have a finish that makes
them appear to be stainless; they're better than nickel plated, but they're not
stainless. I hope they hold up to the weather.<BR><BR>Here is the antenna fully
assembled, ready for tuning and testing:<BR><BR><IMG alt=""
src="http://www.worldwidedx.com/members/moleculo-albums-gizmotchy-2-meter-4-element-beam-picture1763-assembly-finished.jpg"
border=0><BR><BR>In this picture, I've already aligned all of the elements.
There is probably an easier way, but I accomplished this by having a helping
hand hold a straight edge up along all of the vertical elements. I then rotated
each of them until they were square against the straight edge. As you can see
from this pic, the boom is really very sturdy for an antenna of this size. In
fact, the large boom diameter is really unnecessary and just adds extra weight.
However, I'm sure that Gizmotchy uses the same boom and element hubs for more
than one antenna design, so I'm sure it helps keep the costs down, which is
perfectly acceptable to me.<BR><BR>I have one last observation about the
assembly before I move on to tuning and testing. Each of the element's radials
are attached to the hub by a small hose clamp. After tightening the clamps, the
fit is good although there can be a little play on each rod, which isn't a big
deal. The package comes with small sheet metal screws, one for each of the
radials. The instructions do not indicate what these are to be used for, but if
you look carefully at the the assembly diagrams, you can see that they are to be
used as an augmentation to the hose clamps to secure the radial to the element
hub. however, none of the aluminum parts are drilled and tapped for these
screws. There is no possible way that anyone can drive one of these small sheet
metal screws into the aluminum rod without it being pre-drilled and tapped for
assembly. I tried to attach one screw without success, then tried to hand drill
it, and then quickly realized that the only way to accomplish this would be to
use a drill press. For this 2 meter antenna, the additional locking screws are
completely unnecessary, so I scrapped the idea. I hope their bigger antennas
have the element radials drilled and tapped from the factory.<BR><BR><BR>Next,
I'll talk about tuning and then finish mounting the antenna for use. I also have
some factory test materials to share. Stay tuned...</FONT><!-- google_ad_section_end --> </DIV>
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<DIV><FONT face=Tahoma>Fonte: The Worldwire Radio
Forum</FONT></DIV></BODY></HTML>