1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice
Dismiss Notice
This forum does not allow a single user to have more than one username. If anyone wants to change their username contact an admin and it will be done. Multiple accounts belonging to the same member will be deleted without warning.

Home Made 2 Element

Discussion in 'Home Brew' started by HomerBB, May 4, 2009.

  1. HomerBB

    HomerBB Sr. Member

    Joined:
    Jan 4, 2009
    Messages:
    3,702
    Likes Received:
    1,985
    This one I put together on Friday, and have worked a lot of skip on Sat and Sun afternoons:



    [​IMG]

    It was this before it was my antenna:

    [​IMG]

    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.
     

  2. W5LZ

    W5LZ Crotchety Old Bastard

    Joined:
    Apr 8, 2005
    Messages:
    6,832
    Likes Received:
    805
    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!
     
  3. Radio Tech

    Radio Tech Radio Operator

    Joined:
    Sep 9, 2008
    Messages:
    852
    Likes Received:
    260
    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.
     
  4. HomerBB

    HomerBB Sr. Member

    Joined:
    Jan 4, 2009
    Messages:
    3,702
    Likes Received:
    1,985
    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.
     
  5. HomerBB

    HomerBB Sr. Member

    Joined:
    Jan 4, 2009
    Messages:
    3,702
    Likes Received:
    1,985
    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.
     
  6. W5LZ

    W5LZ Crotchety Old Bastard

    Joined:
    Apr 8, 2005
    Messages:
    6,832
    Likes Received:
    805
    :)
     
  7. RickC.

    RickC. Hopeless antenna junkie

    Joined:
    Mar 30, 2009
    Messages:
    402
    Likes Received:
    7
    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
     
    #7 RickC., May 4, 2009
    Last edited: May 4, 2009
  8. HiDef

    HiDef Active Member

    Joined:
    Aug 16, 2008
    Messages:
    543
    Likes Received:
    9
    This is real radio.

    Great stuff.
     
  9. HomerBB

    HomerBB Sr. Member

    Joined:
    Jan 4, 2009
    Messages:
    3,702
    Likes Received:
    1,985
    Thanks, guys.

    I am using a director only.

    It seems to walk the dog and kick the cat for what it is.
     
  10. RickC.

    RickC. Hopeless antenna junkie

    Joined:
    Mar 30, 2009
    Messages:
    402
    Likes Received:
    7
    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
     
  11. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

    Joined:
    Oct 23, 2005
    Messages:
    6,998
    Likes Received:
    1,966
    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?
     
    #11 Marconi, May 5, 2009
    Last edited: May 5, 2009
  12. HomerBB

    HomerBB Sr. Member

    Joined:
    Jan 4, 2009
    Messages:
    3,702
    Likes Received:
    1,985
    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.
    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.
    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
    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.
    I hope that was a little less muddy.
    Who knows, you may make a smarter man of me...
     
  13. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

    Joined:
    Oct 23, 2005
    Messages:
    6,998
    Likes Received:
    1,966
    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.
     
  14. HomerBB

    HomerBB Sr. Member

    Joined:
    Jan 4, 2009
    Messages:
    3,702
    Likes Received:
    1,985
    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
     
  15. W9WD

    W9WD Guest

    You're a very creative person Homer
     

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!