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MY11M megalodon, Yagi antenna build

Geoexplorer69

Active Member
Sep 18, 2024
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So after looking at the selection of eight element Yagi antennas oh wait I didn't find any. I decided that I could build a better one for less money that would ot perform anything Any company out there could produce. I have a bunch of 6061 2 1/2",and 3" Square tube I can easily source heavy duty aluminum elements at least the aluminum tubing to make the elements thy will be heavy walled and telescope largest diameter to the smallest diameter at the tip. DX engineering has all the little parts and pieces and mounting hardware I could ever want, including truss line and stainless steel hardware so I sharpened my pencil get some calculations and here's what I came up with and by the way, I am gonna build this. That's just the kind of guy I am.

The boom's finished length will be 48 feet. I'm building this as an OWA Yagi antenna it will be direct fed from a.max 20 1-1 balun and tuned either at 27.525 MHz or 27.550 MHz haven't got down to that part yet however this sets perfectly in line with the frequencies that I run also knowing that this is going to have more of a U-shaped curve as far as SWR rather than a steep drop off or V-shaped if God forbid you're dumb enough to use a gamma match and to those of you that are using gamma matches yes I have one on my four element.serio and that's the reason why I don't like gamma matches. Even if you convert to a hairpin match, you're still run into the same problems on band width not so much for tuning. A hairpin is superior to a gamma match imho. And if you wanna argue about it, well please go argue with the closest wall in your residence. Thank you..

After looking at this and deciding OK, let's get some metric tape measures out and start figuring this stuff up. Let's get a hold of DX engineering and get the parts coming. I started doing some numbers on the DBD and the DB ground reflection gain ( DBI is all marketing hype )then I looked at the ERP. Wow, just wow and I don't push power well any more power than my 991 can pump out but I do use high-grade coax Messi and paoloni ultraflex 10 including their proprietary connectors so there's gonna be something like a .6db or so line loss in the 97 feet run that I have including the rotor loop. So yes I do have an amplifier but it's only a 200 W custom built fully A/B biased side band only with Toshiba C pills. no preamp.

I'm working on the direct element spacing right now because my 64 year old brain suffers from some CRS I take a lot of notes. I ask Google AI stuff but the problem with Google AI is that it has cost me money and hair loss by giving me bad information and lots of times I have to go. Hey, are you sure maybe you should sharpen your AI pencil or double check your data .

so what am I getting at? thank you for asking !

All right the bottom line is, I'm not bragging what I need is a great antenna builder to chime in preferably somebody in Europe or Australia or any place besides the USA that uses metric measurements and let's see if our numbers for the spacing between the Director and the first reflector spacing the rest of the elements and other measurements can jive , and yes, I am running dual truss lines to keep it perfectly flat I know the angle that I need to run from the top of the mast extension so that is dialed in.

It would be absolutely awesome to hear from some great antenna builders your honest input, other than that YES I am absolutely nucking futs that has already been established.
Cheers
 
Last edited:
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If you have or can download EZNEC Pro 2+ v7 (free download), you can design and tweak your Megaladon yourself in metric dimensions without much trouble.

Good luck with your monster.
7 3
 
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If you have or can download EZNEC Pro 2+ v7 (free download), you can design and tweak your Megaladon yourself in metric dimensions without much trouble.

Good luck with your monster.
7 3
Hey, thanks for the reply. Yeah I looked into that definitely gonna use it and since I'm posting on here again, my bad for thinking there wasn't anybody building An 8 element Yagi. There are a few, but their booms are either too short or too flimsy for my liking
 
Your boom will definitely need some beefy square tube, beefy splices and guys. You should be a EU powerhouse with 8el on 11m.
 
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Yes true but I have enough 6061 t6 2 1/2" heavy wall square tube and I have 3" as well also my plan is to use a 3" square tube section 12'-13' long for the center and run 2 1/2 " for the outer booms they fit nice n snug together then I have the DX engineering clamps and mounting gear to run the elements underneath the boom the mast will stick up 5' above the mounting plate, and then I will run two each guidelines from the truss top on either side, I have the stainless steel hardware and the turnbuckles to support the boom and enough for two sections either side of the truss pipe. I already have a spool of mastraint-M 3mm line for the guy lines on the boom.
Right now, I'm just doing the number crunching on the element spacing and lengths I have a bunch of different size diameter heavy wall aluminum tube that should work well for the elements probably gonna be overkill, but that's OK then I decided to split the ends and use some of the stainless steel split end clamps from DX and also to run some sections of small diameter, Poly line Down through the center of the elements to keep any harmonic wind vibration that I'm sure I'm gonna get way out here in the SW desert dampened down.
That's my plan anyway thank you
 

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