Homebrew 70cm oscar yagi.

Discussion in 'Ham Radio Discussions' started by KC4UMO, Feb 4, 2008.

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  1. KC4UMO

    KC4UMO Ham Member QRZ Page

    Carried over from this thread:
    http://forums.qrz.com/showthread.php?t=151194


    First I like to thank the following.
    N4CZT Doug, For getting me in voled in Amateur satellite.

    These guys helped me make my mind up on what I wanted to do.
    K9STH Glen
    KA4DPO John
    WA9SVD Larry
    KL7AJ Eric

    W9GB Gregory, For helping me with some vital information

    This project went pretty smooth. Time to draw out and plan was 3 days. There was a half of day spent preparing the material. And another half day assembly.
    Years of testing ahead...

    There are a few things with this antenna I deviated on.
    I could had ordered stuff but wanted to do this with stuff found locally.
    One was the element insulators.

    The yagi is a 10 X 10 RHCP.
    Total cost out of pocket was $21.00
    Boom is 72 inches.
    Elements are 3/16 dia.
    Driven element is 3/8 dia.
    Gamma fed
    Elements are insulated from boom.
    Element plane is off set by one quarter wave length.

    Complete preparation and assembly located here:
    http://www.gokarters.com/vbforum/showthread.php?p=14986#post14986

    Comments are welcome..


    [​IMG]
     
    Last edited: Feb 4, 2008
  2. KC4UMO

    KC4UMO Ham Member QRZ Page

    Just worked AO-51 and VO-52.
    My signal was better than ever before!

    Had no problems getting into or hearing either bird.
    That was a good test.
    Both birds were on a short pass. So had trees to go through.
    VO-52 I used the new atenna to transmit on.
    AO-51 I used the new antenna to receive on.

    10 watts, no preamp.
     
  3. WA9SVD

    WA9SVD Ham Member QRZ Page

    Can't quite make out the feed and phasing lines from the picture. What did you use for element insulators?

    Looks pretty good, tho. Congrats on the contacts.
     
  4. KC4UMO

    KC4UMO Ham Member QRZ Page

    Look here. It has close up of everything.
    http://www.gokarters.com/vbforum/showthread.php?p=14986#post14986

    thanks

    The feed is Gamma.
    Insulators are sheet rock anchors.

    [​IMG]
    [​IMG]
    http://www.gokarters.com/vbforum/attachment.php?attachmentid=583&stc=1&d=1202083650[img]
    [img]http://www.gokarters.com/vbforum/attachment.php?attachmentid=584&stc=1&d=1202084675
    [​IMG]
     
    Last edited: Feb 4, 2008
  5. KR2D

    KR2D Ham Member QRZ Page

    Good job, OM!
     
  6. N6VMO

    N6VMO Ham Member QRZ Page

    Great idea with the wall anchors...good job...
     
  7. W0LPQ

    W0LPQ Ham Member QRZ Page

    The only concern I would have is ... how do the insulators hold up to sunlight?

    Some plastics don't like it ...

    Great job otherwise and nice to see accomplishment..!!

    Keep up the good work..
     
  8. KC4UMO

    KC4UMO Ham Member QRZ Page

    Thanks for the comments gents.
    The wall anchor idea was stumbled on by accident.
    I wanted something that could be found local.

    W0LPQ
    I am thinking the same thing on the plastic.
    But 2 things come to mind.
    I know UV rays will get the best of them over time. But how long?
    Next, changing these out are so quick and at .6 cents a piece.
    I am thinking of coating them with something to block some of natures elements.

    Thanks for your comments.
     
  9. WA9SVD

    WA9SVD Ham Member QRZ Page

    I agree it was an excellent idea to think of the anchors for insulators, but also wonder about the longevity when exposed to the elements. But you have already considered that, it seems. The resistance to elements depends upon the exact palstic used. With various cable ties, reputed to be nylon, the "black" type will last at least several years. The "white" ties and other accessories can last for as little as 3-6 months if eposed to sunlight. Other colors may not be any more resistant than the "white" ties. Without knowing the material used for the anchors, it's not possible to predict how long they will last. Hopefully years, rather than months.
    But nice job.
     
  10. KA4DPO

    KA4DPO Platinum Subscriber Platinum Subscriber QRZ Page

    Nice Job.......:)
     
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