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Home Made 2 Element

HomerBB

Sr. Member
Jan 4, 2009
3,933
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Rogers, Ar
This one I put together on Friday, and have worked a lot of skip on Sat and Sun afternoons:

2eltoptr.jpg


It was this before it was my antenna:

1600use Out Dryer.jpg


Driven Element -------- 108" each half, or 18' 0" total

Director Element -------- 100" each half, or 16' 8" total

Boom length -------- 34" total to element centers

gamma match -------- 24" x 3/8" tube with centered RG6u coax capacitor clipped and slid until matched (you know the drill)

The front element is isolated from the boom with a piece of plastic composite material (recycled environmentally friendly ;)), and the reflector is attached directly to the boom.

The entire thing is from parts of the clothes line. The aluminum is NOT round, but I do not run power. The thing lacked enough parts to complete the total element lengths, so I finished them out with 1/4" all thread.

I've gotten a LOT of DX action on it.
 

May not be the most elegant thing in the world, but it works, right? One thought is to play with that boom length a bit, see what happens when you lengthen it. As if you hadn't already thought of that....
- 'Doc


then again, you had half of a 1.2 Ghz thru 6 meter quad before you 'messed it up... change the 'T' shirts to pink, naturally!
 
Not bad at all.

One question. Why did you insulate the driven element? Was this in thought of dropping the noise level some? With the gama match which is nothing but a capacitor, I wonder how much more capacitance it adds to the gama since the driven element is in "free space".

Alsothink about Doc's comment on boom length.

Again, not bad. Congrats. I built many of these for 10 meters over the years.
 
Not bad at all.

One question. Why did you insulate the driven element? Was this in thought of dropping the noise level some? With the gamma match which is nothing but a capacitor, I wonder how much more capacitance it adds to the gamma since the driven element is in "free space".

Also think about Doc's comment on boom length.

Again, not bad. Congrats. I built many of these for 10 meters over the years.

I had begun this trying to use a delta match and both elements mounted through the boom, neither insulated.

I could not get a match by any means with that system.

Because the materials had been put into the effort, I decided to go more traditional with the isolated driver and a gamma. It worked.

I was able to get a

1:2:1 on ch1
1:3:1 on 20
1:4:1 on 40

I am not able to answer your other questions as I have no idea. Others of you probably can figure that out better than I can.
 
May not be the most elegant thing in the world, but it works, right? One thought is to play with that boom length a bit, see what happens when you lengthen it. As if you hadn't already thought of that....
- 'Doc


then again, you had half of a 1.2 Ghz thru 6 meter quad before you 'messed it up... change the 'T' shirts to pink, naturally!

Probably will fool around with the boom length some.

As for the 1.2 Ghz through 6 meter, I'd have to listen only after I bought the necessary equipment. Not licensed for it.
 
Love it! Clotheslines, eh? HA!

I had the same question about insulating the driven element from the boom when using a gamma match, but OK. I've used hairpin (or Beta, according to Hy-Gain) in that situation several times with good results.

Many people get caught up with how many elements a yagi has (4 vs. 3, 5 vs. 7, etc.) and I'll bet most of them have never used a 2 el yagi and know what an effective antenna it can be.

I know you were working with the parts you had from the clothesline, but you probably know with a 2 el yagi (and with a 5 el, oddly enough) it's possible to get a good direct match to 50 ohm coax. I'd have to run the numbers to be sure but I think that'd be element spacing in the vicinity of 5 feet at 27 MHz. I just looked back over your post though-- is this using a director or a reflector? (you say both!).

I built a chicken brooder this past weekend. I like your project MUCH better.


Rick
 
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Then the shorter boom isn't a handicap. A good 2 element yagi is an effective antenna- I've used them on 10, 15, and 20 at various times over the years with very good results. They have always performed better than they had a right to, and could really surprise you sometimes with real time A/B comparisons to dipoles, inverted vees, and verticals!


Rick
 
Homer your description is confusing. You describe using a reflector, but no reflector is noted in your parts list. Your parts list suggest instead that you have a driven element and a director. Your measurements also suggest the use of a director. ????

You also note in another post that the driven element is insulated, suggesting that is typical use with a gamma. That is not typical in a traditional yagi multi-element design where a gamma is used.

When using the delta match the driver needs to be insulated from the boom and split at the center as a dipole. How did you insulate it with thru the boom construction? Could that be why it did not work?

My yagi's using 5/8, 1/2 or 3/4, 5/8 tubing all have a driven element about 207" long at CB resonance. Your driven element is 216" long. Did that put you below channel one?

Can you clarify?
 
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Homer your description is confusing. You describe using a reflector, but no reflector is noted in your parts list. Your parts list suggest instead that you have a driven element and a director. Your measurements also suggest the use of a director. ????
Sorry if Iwas unclear. If I said I used a reflector it was an error I failed to catch. I am a hunt and peck typist. You are right. I used a driven element and a director.
You also note in another post that the driven element is insulated, suggesting that is typical use with a gamma. That is not typical in a traditional yagi multi-element design where a gamma is used.
The driven element is NOW insulated. Originally I started out with it going through the boom uninsulated. By using the word typical I meant to say a more commonly used means of matching rather than a more typical arrangement.
When using the delta match the driver needs to be insulated from the boom and split at the center as a dipole. How did you insulate it with thru the boom construction? Could that be why it did not work?
It could be. I am not a scientist, merely a guy trying things out. Theorists have a blast working with the science, a dimension I can't begin to appreciate. I like the feel of the materials in my hands, and the surprising results when they work, or not. As for the split dipole for delta matching, one resource I read stated that the dipole was not split when the delta was employed. I can't make a case either way, except his claim was the delta was successful because the width from the center of an unbroken dipole in conjunction with the proper length of the delta arms resulted in finding the exact position along that unbroken dipole where the impedance (correct term?) was a match to the feedline. His argument for the uninsulated dipole was beyond me. It didn't work for me, yet. I am going to try it again
My yagi's using 5/8, 1/2 or 3/4, 5/8 tubing all have a driven element about 207" long at CB resonance. Your driven element is 216" long. Did that put you below channel one?
Actually, despite my eight bands of frequencies, it seemed to be improving as I went up the frequencies, not down. I began to be unable to get the SWR meter to calibrate going down.
Can you clarify?
I hope that was a little less muddy.
Who knows, you may make a smarter man of me...
 
Thanks Homer. I misspoke about the delta match, you are correct. I was in error and thinking of a beta or hairpin type matcher that works with a split element.

Are your elements made of wire or tubing? The 216" driver length still seems like it is way too long for 11 meters if using tubing, if wire it would be closer.
 
Thanks Homer. I misspoke about the delta match, you are correct. I was in error and thinking of a beta or hairpin type matcher that works with a split element.

Are your elements made of wire or tubing? The 216" driver length still seems like it is way too long for 11 meters if using tubing, if wire it would be closer.

It's tubing.

I used the other fellows formula - Lemme see if I can find it - and it worked out that way, unless I goofed it.

Here is what I was attempting to do when I gave up.

I am going to try it again with additional materials.

Using Delta Matching on HF Beams
 

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