Multi-Band Yagi vs. Log Periodic - What's the Difference?

Discussion in 'General Technical Questions and Answers' started by W3ALX, Oct 2, 2008.

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  1. K5STA

    K5STA Ham Member QRZ Page

    I have a HG TH7DX up 65' on a crank up tower on one side of house and a old style W hexbeam on the other. Each been has been in the air from 1992 to today. The TH7DX has been taken down 4 times for repair becouse of hurricanes
    the hex only once. I can tell you that the TH7DX out preforms the hex only on 10 meters by 1-2 s units.15 and 20 meters they are tit for tat. I am fixing to take the hex down and build the broadband hex to take its place. Good beam Steve, thanks for all your work.

    Stew
    K5STA
     
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    ::There really aren't any good ones currently on the market, at least not in the U.S. (Europe and Japan have several of their own manufacturers that make stuff they don't export to the U.S.)

    The Cushcraft model A27010S http://cushcraft.com/comm/support/pdf/AR270.pdf isn't terrible, but is small and doesn't have much gain. It may be mounted either vertically or horizontally. For 2m or 70cm work, I normally want something larger with more gain than this has.

    I use separate beams for these two bands, as does anybody serious about working much beyond their horizon. M2 and Directive Systems both make very good VHF-UHF beams.

    WB2WIK/6
     
  3. W3ALX

    W3ALX Guest

    Steve,

    Thanks for the excellent post! What part of NJ are you from? I'm also originally from NJ and later headed westward, but stopped shortly after crossing the first bridge, landing in SE PA, just west of Trenton.

    So if I were going to make a heads up comparison between a yagi and LPDA, lets say a Mosley Pro 57b vs. a Tennadyne T10, would it be a toss up? The constants are the boom length, sq. ft., F/B ratio, swr. The gain goes to the pro and flat bandwidth to the T10. The pro may be a bit more durable but the T10 more maintenance free. So what would be the decisive factor?

    Thanks!
    Bruce
     
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    ::A very important factor to me would be "availability." If you order each one today, when would you receive it? I bought my Tennadyne under the old, original management (when they were in TX) and received delivery two days later via UPS. I don't know if they're still shipping "from stock," but if so, that's a very compelling factor because as far as I know Mosley doesn't have any stock of anything and often has a 3-4 month backlog. So, you might check that.

    73

    Steve WB2WIK/6
     
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    ::Forgot this part...I'm originally from NNJ, a little town called Springfield in Union County, about 60 miles NE of Trenton.

    Haven't lived in NJ in more than 20 years, though.

    Been in Los Angeles since mid-1988.

    73

    Steve WB2WIK/6
     
  6. W3ALX

    W3ALX Guest

    Don't plan on doing the install until next spring. Is that the only other factor?
     
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    ::Yes, but it's a very big one. An antenna "on order" doesn't make many contacts.

    If you want to install in Spring 2009, I'd take delivery of the antenna "now."

    Seriously.

    If you wait until Feb-Mar 09, especially if it's a Mosley, the entire summer might slip by while you're still waiting for it...read some of the on line reports regarding "delivery."

    WB2WIK/6
     
  8. KG7OY

    KG7OY Ham Member QRZ Page

    Interlaced Yagi

    I have used an interlaced full size yagi antenna for 20 years. 15 & 20 meters.
    It is home built on 2 inch aluminum irrigation pipe. I built brackets and use U-bolts to attach the elements to the boom. Texas tower has the aluminum pipe in various length and and size (for the elements). They slide together. Hose clamp has held them together. Gamma match for each antenna.

    I use the MFJ remote antenna switch to switch from 15 meters to 20 meters from my radio room 60 feet away.

    It all works very well, and only one coax cable to the top of the tower!!

    KG7OY, Bill in Methow Washington.

    Anyone wanting information on this antenna can email me. kg7oy

    btuin@hughes.net
     
  9. K0RGR

    K0RGR Premium Subscriber QRZ Page

    Actually, many tribander designs are fairly narrow. Very few will operate well over the entire 10 meter band, and some won't cover the entire 20 meter band well, either.

    I went from a Mosley TA-33 which was quite narrow, to a KT-34 which was quite broad. Even the KT-34 didn't like the high end of 10 very much. The Mosely was pretty poor up there.

    A friend here has the Cushcraft and likes it.
     
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