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Gizmotchy 2 Meter 4 Element Beam Review
- Thread starter Moleculo
- Start date
this is an old threat, but I just got a gizmo 4 element I set it for 11 meters. compare it to my 4 element yagi almost if not equal. the big advantage is the dual polarization. I love this feature cause it work so well. not able to get it any higher than 10 feet on my roof my swr was a stable 1.9. with 50 watts output. I could work just about everything I could hear. I like it. it does work well. the big issue is that you have to get it high at least higher that ten feet off the ground. the other plus is that not a big expensive rotor is needed. a simple radio shack rotor turns mines with no problem,
Ok, so your experience is counter to what Mole (and others) have been talking about with this antenna regarding measurements (for a lot of this thread).
Based on finding this (old) thread, I went and purchased the 4-element 2m version, and I received it today (shipping cost from Walcott Radio was OUTRAGEOUS!)
The supplied instruction manual still shows what Mole (and a couple others here) are calling "reversed" measurements, and those measurements are foreign to any yagi design calculations that I could find online.
So if what you said is true, that would be AWESOME !
It *IS* an extremely well built affair, but there are no thumb screws to tighten the element trunions to the boom - they appear to be 7/16's stainless bolts now.
2 complaints I have so far: It's packed TOO well! I could hardly get the box open - all stapled to beat-heck with those large copper plated GIANT staples, just to find more smaller steel staples sewing some inner box together.
Then, when I DID get the box open, it exploded with some sort of Styrofoam-like peanuts. TONS of them! They didn't need to do that!
Trivial, yeah, perhaps.... But what torques me off is that somehow these peanuts weren't fully cured, and some were stuck all over the boom, and had to be peeled off. And they left some of their material on the boom where they were stuck, and I now can't I can't remove that stuff with the Acetone that I have here. Are they urethane perhaps ? What do I need to use to get this stuff off? Paint stripper maybe.
Anyways, when (if ??) I get this junk off of the boom (to where I can slide the element trunions on the boom, I too will try the (original) spacing in the manual, and post my findings analysis.
Someone mentioned that the company now offers a phasing harness to make this "circular" polarized, but I found no such offering on their web page.
BTW, who took over MFJ/Hygain/Hustler etc.? They used to offer a cheap 3-4 element vert + horiz 2m beam, but with MFJ gone, none of that stuff is available from anyone anymore.
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Ok, after spending way-way-WAY too much time going down you guy's (Mole & DXER's) rabbit hole, and corresponding back and forth to Tom Charles who designed this antenna, the conclusion is that the above statement is dead wrong.
The correct spacings are in the current version on the manual Copyright 2012 as shown below, and from the reflector are: 0-21-18-13.
I will continue to assemble my new antenna with these proper spacings, and report back with my findings.
As far as the (urethane?) packing peanut residue stuck on the boom, no chemical(s) that I have in my shop would touch it, so I had to use steel wool and a LOT of elbow grease to get that off. There was a slight payoff in that it made the boom extremely bright and shinny (FWIW).
Attachments
Did you use steel wool or stainless steel wool?
I used to work in food processing and have seen regular steel wool leave contamination behind that later showed crosion on both aluminum and stainless.
It's even worse on stainless, if you did use regular steel wool I would suggest you go over it with a Scotch Brite pad to remove any small particles of steel that may remain.
73
Jeff
Wow!, - thanks, I did NOT know this!! I'll go over it real good with Scotch Brite + final clean with Brake Klean and a cotton cloth.
Update:
I finally assembled my Gizmotchy 2 meter beam, and I am impressed !
I have some minor complaints about the parts shipped, and Tom's e-mail followup on them, but I *think* I got them worked out. i.e. them shipping two 4-inch Gamma tubes instead of a 3-inch and a 4-inch tube.
Tom said not to cut them, but I ended up cutting the 4-inch one for the Horizontal down to 3 inches like the instructions show. If you try to use one of the supplied 4-inch gamma tubes for the Horiz Gama match, and try to set it up for the dimensions shown in the instructions, it will bottom out in the Gama sleeve, and it will short out !
But looking back on it, if the instructions were better designed, they could have mentioned to be careful not to bottom out the new, longer 4-inch gamma tube for the horizontal Gamma match, and just to let the excess length extend beyond the clamp strap for the driven element. So i'm unhappy about that part
What I *AM* happy about however, is the quality of the workmanship of the thing. It was a true joy to assemble. I was impressed the mechanical design of the Gamma match (even though I'm P.O.'d about that 4-inch tube shipped instead of the advertised 3-inch tube).
What I'm *ALSO* impressed with, is how lucky I was with the SWR's !!
With the measurements in the instructions for the Gamma match(s), my SWR's from 144 Mhz to 148 Mhz were lower than 1.3 : 1 (1.29 being the highest actually).
So I *might* tweak with it a bit, but it looks so good the way it is, I might just leave it alone.
Take a look at some pic's I took tonight !
I finally assembled my Gizmotchy 2 meter beam, and I am impressed !
I have some minor complaints about the parts shipped, and Tom's e-mail followup on them, but I *think* I got them worked out. i.e. them shipping two 4-inch Gamma tubes instead of a 3-inch and a 4-inch tube.
Tom said not to cut them, but I ended up cutting the 4-inch one for the Horizontal down to 3 inches like the instructions show. If you try to use one of the supplied 4-inch gamma tubes for the Horiz Gama match, and try to set it up for the dimensions shown in the instructions, it will bottom out in the Gama sleeve, and it will short out !
But looking back on it, if the instructions were better designed, they could have mentioned to be careful not to bottom out the new, longer 4-inch gamma tube for the horizontal Gamma match, and just to let the excess length extend beyond the clamp strap for the driven element. So i'm unhappy about that part
What I *AM* happy about however, is the quality of the workmanship of the thing. It was a true joy to assemble. I was impressed the mechanical design of the Gamma match (even though I'm P.O.'d about that 4-inch tube shipped instead of the advertised 3-inch tube).
What I'm *ALSO* impressed with, is how lucky I was with the SWR's !!
With the measurements in the instructions for the Gamma match(s), my SWR's from 144 Mhz to 148 Mhz were lower than 1.3 : 1 (1.29 being the highest actually).
So I *might* tweak with it a bit, but it looks so good the way it is, I might just leave it alone.
Take a look at some pic's I took tonight !
Attachments
Update:
I finally assembled my Gizmotchy 2 meter beam, and I am impressed !
I have some minor complaints about the parts shipped, and Tom's e-mail followup on them, but I *think* I got them worked out. i.e. them shipping two 4-inch Gamma tubes instead of a 3-inch and a 4-inch tube.
Tom said not to cut them, but I ended up cutting the 4-inch one for the Horizontal down to 3 inches like the instructions show. If you try to use one of the supplied 4-inch gamma tubes for the Horiz Gama match, and try to set it up for the dimensions shown in the instructions, it will bottom out in the Gama sleeve, and it will short out !
But looking back on it, if the instructions were better designed, they could have mentioned to be careful not to bottom out the new, longer 4-inch gamma tube for the horizontal Gamma match, and just to let the excess length extend beyond the clamp strap for the driven element. So i'm unhappy about that part
What I *AM* happy about however, is the quality of the workmanship of the thing. It was a true joy to assemble. I was impressed the mechanical design of the Gamma match (even though I'm P.O.'d about that 4-inch tube shipped instead of the advertised 3-inch tube).
What I'm *ALSO* impressed with, is how lucky I was with the SWR's !!
With the measurements in the instructions for the Gamma match(s), my SWR's from 144 Mhz to 148 Mhz were lower than 1.3 : 1 (1.29 being the highest actually).
So I *might* tweak with it a bit, but it looks so good the way it is, I might just leave it alone.
Take a look at some pic's I took tonight !
The instructions with the strange spacing WILL result in a flat SWR. But as we showed when modelled, the gain and rear rejection leave a lot to be desired. As I noted earlier, if you respace it in a more traditional way, you will have to make some adjustments to the element lengths. But the modelling showed what the payoff is.