GIZMOTCHY ANTENNA REVISITED 6 METER

[Happy_Hamer]

Well it has been awhile since the Gizmotchy 10/11 meter antenna was discussed here.

For those that do not know or have forgot, we tried a 10/11 meter Gizmotchy antenna. The antenna assembled with a few "bugs". Assembly could be done for an average user. The problem I found though, the antenna was not a simple assembly without using a drill. I also would have had to buy more robust "hose clamps" to hold the elements together.

Now I did get the antenna put together. Using the directions the SWR was right on for horizontal and vertical. I made contacts using a 2970DX. The antenna was on a 20 foot mast so we could easily "tweak" if need be. After a day of testing and making contacts, we decided to call it a night and start over the next day.

We had some light winds over night and when we went back to the antenna the next day, some of the elements fell off and had to be reinstalled. The "automotive" type hose clamps could not tighten down enough to hold them together, in fact a few stripped out from over tightening. The rest of the day was just as much of a pain in the ass because it was windy and elements continued falling off and apart.

Now you can drill out the hubs and elements and make it a more secure assembly. We were looking at it though from a user receiving the antenna and only having basic hand tools to assemble.

These elements were between 100-109 inches long and has some weight to them that required stronger clamps and drilling. With them being as long as they were and the weight, the leverage affect was amplified causing them to wiggle and come apart, again without drilling it.

I did offer the antenna to a forum member but because of a family emergency could not deliver it. So after some time, the emergency was over and I offered it to any forum member who volunteered, no-one wanted to take it and test.

So here we are, revisiting the antenna.

Now if we didn't have such long elements and boom, the antenna wouldn't flex so much. Problem with that, you shorten the boom or elements, it would no longer work for the intended band.

Well the other day I was on the Gizmotchy web site and see they now offer a 6 meter antenna with the same design as this 10/11 meter antenna.

HEY!!!!! DING DING DING!!!!!!!

 

[Happy_Hamer]

Well do you see where we are going with this? Yup we are cutting this thing down to try it as a 6 meter antenna.

The hubs, boom and gamma match all appear to be the same. Of course the boom, elements and gamma match are shorter.

(i'm using Giz for the rest of this thread to identify the Gizmotchy antenna, yeah i'm lazy LOL)

Using the directions from the Giz website I think this should work with the material from the 10/11 meter antenna.

Horizontal and Vertical Polarization Twin Feed

Gamma matched, both horizontal and vertical, to 50 ohms

All Aluminum Seamless Construction

Forward Gain: 9 DB

Boom Length: 9 feet

Weight: 10 lbs

SWR: 1:1

See Attached

 

[Happy_Hamer]

I also need to include the directions to the 10/11 meter antenna for reference.

 

[Happy_Hamer]

Here are a few things I need to figure out,

Boom length for the 11 meter is 12 foot 3/4inch long

Boom length for the 6 meter is 9 foot long

I need to cut it down so the 3 sections of the boom can be cut down for a proper assembly.

I also need to make sure I can cut down the gamma match to work on 6 meter.

Another thing to consider is the gamma match spacing, because that will be very difficult to change. I am hoping that maybe Giz modeled the 10/11 and 6 meter using the same gamma so they have fewer parts for his inventory.

Any Eznec users out there to look into this??

Next post will be some pictures I took of the boom and gamma match.

 

[Happy_Hamer]

boom lengths

The top one is the center piece of the boom assembly, the second one is the length of the center section.


The third one is the longer piece of a boom end length

The fourth one is the shorter piece of the boom end length.

 

[Happy_Hamer]

Now the gamma match

The first one is the gamma that the directions show should be the longer one on top and short on the bottom

The second picture just shows the longer one, of course it slides so that picture is useless LOL, and the same for the last image which is the shorter one. The big difference is the nylon inserts then we can match the lengths for 6 meter.

 

[Happy_Hamer]

These are pictures of the SO239 part of the gamma

the first one is just the SO239 part

the second one has the arrow showing my spacing concern

 

[Happy_Hamer]

So, I guess my first move is to leave the center section of the boom as is.

And the longer end piece is 60 inches, so I should just cut it to 54 inches so I would have the 9 foot boom needed.

No need to use the shorter 52 inch end piece.

What do you guys think?

 

[Happy_Hamer]

Well actually I should connect the two pieces together since I measured the boom pieces without considering the insert length when joined.

So just connect them and hope I can get the total 9 foot?

 

[AudioShockwav]

That is what it looks like.......center section 5 foot long, one end of the boom 4 foot 6 inches with 6(?) inches of overlap (?) 9` total...well try it Hamer.

73
Jeff

 

[Happy_Hamer]

WELL GOOD NEWS!!!!!

I assembled the center section and the long end section and I am a 1/4 short of 9 foot

Looking at the element spacing in the directions, the 1/4 lacking should not matter

 

[Happy_Hamer]

Now the gamma is the next step

 

[TonyV225]

BILL DONT LET THAT THING THROW YA!!! LMA!! op:

 

[Happy_Hamer]

I have more information on the gamma match. The following are some print screens of the gamma bracket, tubing length, and gamma spacing.

I am in Kansas City for a few days, once I return I will measure the 10/11 meter gamma and start cutting stuff down for 6 meter.

 

[Happy_Hamer]

Looking at the other picture I posted (post #7), it appears the spacing is the same on both brackets, (See Image)

I can see with the tape measure it is 4 inches and some change

It is suppose to be 4.375 inches, (4 3/8)

I will not be able to tell exactly until I get home, but it looks promising