I’m in the process of building my second 12 element yagi. I sold the first one along with my entire station 6 years ago in anticipation for a move that never happened. It worked so well that I wanted another one. My boom material is inbound, and I’ll pick up the element material locally, but I’ve managed to put together the T-match components from what I already had laying around.
I’ll post more as I progress.







Pic of old installation.

When I first got on VHF I was 15 or 16. A few guys helped me with stuff, and one liked to build VHF antennas, beams (used a gamma match maybe, ? or something with a coax loop). He gave me a 9 element beam when he was ready to build his next.

My mother had an old clothesline pole in the yard, for one of those "umbrella" clothes lines. I mounted the beam to that pole. We lived on top of a hill at almost the highest point in the county. I could work repeaters from Pennsylvania to Watertown NY (3 hours drive time between them) on my Santec HT and 4 watts at about 7ft. I would run out the back door and swing the beam by hand and be able to work at least 60 miles in each direction.

I started messing with them a little - you can make a pretty simple one thats somewhat effective out of clothes hangers and a wooden boom. Or at least I thought you could, since I had no test equipment and had such a geographically good position.

Please keep posting pics OP - hope you inspire folks to try building a beam themselves, especially working with the T match. I could probably use a 440 beam myself for FM.

If I was building a beam these days I'd be looking at the loop fed designs instead of messing with a gamma or T match system.

I built a couple of 70cm versions years ago also, antennas have always been my favorite part of ham radio. Somewhere I have a picture of one alongside the 2 meter version pictured above.
Found it! The octagon in the foreground is a 40 meter magnetic loop I built also.

Different strokes for different folks. A loop would give me better side rejection, but I’m not looking for that.
I run FM simplex & like to be able to still hear my local friends while still being able to hear the distant stations around Arizona.
Flatter terrain may need a different configuration.

My only comment is that your feed point is overly simplistic.
You need to match the feed impedance better.

There are several ways to do this, but the delta and gamma match are the most common, and pretty easy to do.
You will get better performance if you do this.

I’m not done with the feed, it will have a 4:1 coaxial balun to match to the 50 ohm feed.
I’ve done this before, M2 uses the same design, and I understand why.
I’m using this design from an old ARRL Handbook, but reconfigured the element spacing and lengths with a modern yagi modeling program for a little more gain.

Building antennas is one of my faves as well.

6 element 2m from an old TV antenna I dragged out of a dumpster several years ago.

Attached File

That’s what I’m talking about!

Quagi, yeh!

Attached File


This is the style I was referring to.

I machined the insulators for the parasitic elements out of black Delryn. Unfortunately my old eyes failed me when ordering tubing for the boom. I ordered 1.125 diameter instead of 1.25 diameter. The correct size is inbound, and the 1.125 tube will be used for a 70cm yagi that is already on the drawing board.

what did you use to machine those?

this thread is what ham radio is all about

A Hardinge lathe.

CNC?


If I made those on my manual lathe it work take me a week

No, Hardinge hand chucker manual turret lathe, it took me about 30 minutes to turn these out. You’re doing something wrong if it would take you a week.

Baby steps. I got the 4:1 coaxial balun measured, cut, and the lugs soldered on. Waiting on material before moving forward.

When completed it will have very similar performance as this antenna produced by M2, but with larger diameter parasitic elements, a less bulky match system, and a longer boom.
It will cost about 1/3 of what they go for, last longer, and besides that they are great projects.

https://www.m2inc.com/FG2M12

Did you machine those out of Delrin solid rod or tubing?

ID and OD (if you have it handy)?

(are all elements using the same dia. tubing as the DE? I see that you mentioned using parts of the design from an old ARRLHandbook project - what year?)

I thought about using a hairpin match similar to the one for this 6 meter yagi I built years ago, but I already had some of the parts for the T match left over from my earlier antenna builds.
There’s really no reason to have 3 UHF connectors on a yagi either. M2 uses 3 to make replacing the balun easier, not sure if that’s a valid reason considering the extra cost and labor involved.
I didn’t know better when I built this feed system though.??

All parasitic elements will be 1/4” solid aluminum rod.
Insulators were turned from 1/2” delryn.

Driven element will be 1/2” tube, T-match bars are 3/8”

You’re in luck! Just last night I found this link to a lot of designs I’ve based antennas on before including this one.
http://elabweb.hpa.edu/public/projects/KH6HPA/ARRL/ARRL%20antenna%20book/program%20files/ARRL%20Antenna%20Book%2022nd%20Edition/ARRL%20Antenna%20Book%2022nd%20Edition%20Content/15.pdf

My 70cm antenna will be built using the drawings below the 2 meter version as a starting point. I should be able to squeeze a little more gain out by using a modern modeling program to tweak the element length and spacing.

Sorry, insulators are 1/2” OD turned down to 3/8” to form the shoulder, 1/4” ID. The lengths are not very important, just enough to do the job & a little more for longevity.

These will retain the insulators, a little smear of silicone will keep them from corroding. Can’t seem to find them made out of stainless steel.

Interesting - what would you call those metal press-fit-hold-element-in-place thingamabobs?

(or where did you get them from?)

Most hardware stores carry them, but I ordered these on EBay.

https://www.ebay.com/itm/161106263871
I used the same galvanized retainers without sealing them on the last one I built, but after about 6 years a few of them rusted away causing those parasitic elements to intermittently touch the boom when the wind would blow.

They are called push on retainers (some call them push nuts)  and can be had in

stainless from McMaster Carr

Question, why use solid 1/4 inch rod for the elements? Tubing would be lighter. Cost?

Extra weight not that big of an issue? Already had rod on hand? (Phrasing..)

Rod is cheap & easy to find, no other reason.

Yeah I certainly am. I just started with a HF 7x10

I need to find some cheap 1/4" aluminum rod, any online sources?

No, I buy most of my aluminum from Davis Salvage here in Phoenix. I’m not sure if they ship, but the aluminum is sold by weight rather than size or shape.
Might be worth giving them a call.

https://davissalvage.co/

Better to get it done right, rather than right now.

Damn, only styles A and D are available in stainless, I need style B or C. Thanks for the link though!

Just about every major American city has at least one "salvage yard" that sells new metals for reasonable prices.

Also, while you're there, you can look over their scrap piles for pieces that can be repurposed. They're typically sold by the pound, at scrap metal prices.

I found an antenna build article in the 1990 ARRL Handbook (at least) that appears to be what you are using.

In the same section of that Handbook is construction info for a K1FO-design 22-element 432 yagi. I have four of those that were given to me, and I am refurbishing them for use in an EME array. They use similar construction, including the through-boom elements with the retaining push nuts. In my case, the elements are made from 3/16-inch aluminum rod rather than 1/4-inch rod - but I am also considering building a 222 MHz yagi based on the similar design for the 220 MHz yagi presented in those pages, and so I might consider using 1/4-inch rod for those elements.

I too am interested in finding a source for stainless push nuts that I can use on those antennas.

I have found a potential supplier - Misumi USA.

Their part number SPN-6-SUS is a stainless push nut that looks similar to the galvanized ones shown in your photo above - they look like type B from the McMaster Carr diagram. They are metric - the hole is nominally 6mm in diameter (for a shaft diameter of 5.9 mm), which means that the hole size is maybe 0.018" smaller in diameter than a nominal 0.250" (1/4-inch) diameter rod - but since they are push nuts I'd imagine that they might do the trick.

Although I have not (yet) dealt with Misumi USA, it looks like they will sell small quantities to individuals - the single-quantity price is listed as 12 cents, and they claim that they have them in stock.

See https://us.misumi-ec.com/vona2/detail/221000531453/?HissuCode=SPN-6-SUS  

Here's the product photo:



The manufacturer of those push nuts is apparently Ochiai Industrial Fasteners - the data sheet for that style of push nuts is here: http://www.ochiai-if.net/products/pdf/001/001003003001.pdf

As far as buying 1/4-inch aluminum rod online, I generally use onlinemetals.com - their prices are not 'cheap', especially when shipping is figured in, but you can usually get at least a 15% discount if you subscribe to their emails, and for the next three days they have a 20% discount code:



They show two different alloys for 0.250" diameter aluminum solid rod - 6061-T6511-Extruded is less expensive, at a pre-discount price of $0.64 per foot,

https://www.onlinemetals.com/en/buy/aluminum/0-25-aluminum-round-bar-6061-t6511-extruded/pid/1080

and 6061-T6-Cold Finish at a pre-discount price of $1.38 per foot.

https://www.onlinemetals.com/en/buy/aluminum/0-25-aluminum-round-bar-6061-t6-cold-finish/pid/18007

Either way that adds up when you are building a multi-element array, even with the discount.

You’ll have a real hard time trying to jam those metric push nuts on. Even with the correct size I’ve bent them & had to start over. The 70cm antenna will have 3/16” elements, the 2m will have 1/4” elements. Rod and tube are available locally by the pound so they’ll be cheap. If I had to order the material online it wouldn’t be worth building these, I’d just order from M2.

Do you use a jig or tool to push them onto the rod or do you do it by hand?

I'm also wondering about the feasibility of using a conical tool (like a reamer but without the cutting edges) to slightly open up the push nuts - or would that be a futile exercise that would simply end up with push nuts without enough grip?

I push them on by hand. I looked everywhere for stainless to no avail. The last 2 antennas I built started having issues after about 6 years up, with a dab of silicone smeared on each push nut they should last me the rest of my life. I use silicone to seal the SO-239, and balun from moisture also.

Got started on components for my 70cm yagi. T-match straps.

Edit: I managed to finish the SO-239 bracket today also.

Boom is assembled & ready to drill, and picked up the parasitic element material today Got the driven element finished last night.
Tomorrow I’ll cut the parasitics to length and lay out the positions on the boom.
I only paid $6 and change for four 12 foot lengths of 1/4” aluminum rod at the local salvage yard!??

The parasitics are cut to length, boom is all laid out for drilling. I’m waiting on material for the 70cm version before I drill so I can do them both at the same time.

I also made progress on the tower these yagis are going on.





The two lines of conduit across the back of the house are 220v lines that used to power my pair of Henry 2Ks for HF. In due time I’ll utilize them again.

How do you raise and lower that tower?

Is that a Rohn 25 with a hinge base?

Yes, Rohn 25g. Every time I’ve raised one we’ve used  2 men on the roof pulling, and 2 men on the ground walking it up. So easy a caveman can do it.??
....or 4.

Thanks, I have a 70 foot one in the back in sections and am planning on putting it up this summer, but I am not as young as I used to be and climbing it hoisting the sections up in the air was not something I was looking forward to. How much concrete did you put down? I am planning on 3x3x5 feet deep ( with rebar ) and then a house bracket at 18 feet with the top being 35 feet ( I have read more than 1 section above the house bracket is not a good idea, but then others have gone 3 sections above the last house bracket.) and a 20m 3 element yagi on top. But I really have no idea how to do this so I will be hunting a pecking the whole way, hoping I don't kill me or somebody else.

I built a 50 foot fold over mast with a crank so it isn't my first time putting something up, but I was winging it as I went.

Two sections above the eve bracket is as far as I’d go. I used to climb a tower of the same height as this regularly, but like you I’m not interested in that anymore.
I’m hoping this installation will last until I die or longer.??

That would put me about 35 feet.

Thanks

Mine is 38 feet to the thrust bearing, with another 8 feet of mast above it giving me 46 feet at the feed points.

how far above the last guy or bracket?

About 20 feet of tower above the bracket.

I decided to add a redneck panoramic feature to one of my security cameras.??

I had to modify a couple of boom to mast brackets from DX Engineering for the mast to cross boom, and 2 meter to cross boom mounts. The 70cm yagi shouldn’t need anything this stout though.