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ATAS-120 and counterpoise question

Discussion in 'General Technical Questions and Answers' started by KD0CRU, Oct 1, 2008.

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  1. KD0CRU

    KD0CRU Ham Member QRZ Page

    Hi everyone. I've looked and have found tidbits of information but nothing specifically
    touching this topic. I'm a new general and until funds are back in line (just bought a
    857d and 817nd so money is tight) I would like to use one antenna for both base
    and mobile. I do not expect to use mobile a lot but would like the option to be there
    if needed. I've decided to give the Yaesu ATAS-120 a go. Eventually, when funds are available, I'll
    use the ATAS on the car as a permanent solution and get a dedicated base antenna. I am looking
    at the Diamond CP5H but that's another topic.

    My feeble understanding is that if I would like to use the 120 as a base antenna
    that I need a good counterpoise system. I am interested in 12, 20, and 40 meters.
    Now what I don't quite understand is the best way to set this counterpoise system
    up. What I *think* would be acceptable is this:

    8 wires cut at 34 ft connected together at the base of the antenna and spread
    out evenly in a 360 pattern. This would be for 40 meter.

    Do the same for 20 except cut for 17.5 ft then another 10.2 ft for 12 meter. This
    would have a total of 24 wires in a 360 pattern around the antenna and connected
    to the base.

    Would this work or am I totally off here? If it would work does anyone have any
    pictures of their setup? That would give me a lot of ideas on how to do mine.

    Thanks and 73s,
    Robert KD0CRU
  2. KG6OPR

    KG6OPR Ham Member QRZ Page

    The FT-817ND will not work with ATAS-120.
  3. KD0CRU

    KD0CRU Ham Member QRZ Page

    The 857D will. The 817nd will not be used with the 120. I bought both.

    (Edit: I have a buddistick on the way for the 817)
    Last edited: Oct 2, 2008
  4. KA4DPO

    KA4DPO Ham Member QRZ Page

    The ATAS is designed to be a mobile antenna so you don't need full sized radials for 40 meters. Think about the average car. It's about 6X20 feet. If you are going to use it as a base antenna you should elevate it as much as possible and use half a dozen or more 20 foot radials. It will tune just like it should but there's a catch. A mobile antenna is not very efficient so don't expect great results.

    Good luck with it.

    As an aside, for a lot less than you will spend on the ATAS 120, you can get a set of Hamsticks for the car, a tuner, and build a wire antenna for your fixed station. Make a dipole any length that you have space for, the longer the better. Feed it with 300 or 450 ohm ladder line and buy yourself an inexpensive tuner that will tune balanced line. This will work about a hundred times better than the ATAS for fixed operation and depending on the length should load up on most bands. Even an end fed wire will work much better than the ATAS in a fixed station application.

    I know the ATAS is sexy but it is a compromise antenna to put it mildly and the hamsticks will probably out perform it. You just have to get out of the car to change bands.
    Last edited: Oct 1, 2008
  5. KD0CRU

    KD0CRU Ham Member QRZ Page


    Thanks a bunch. You've given me what I need.

    I'm still debating on the dipole. I'll need to measure and see if there is enough room to make the runs I need.
    I agree with the hamsticks. The purchase is still a few months away though and I'll have time to decide whether I go sticks or ATAS for mobile. The big downside is, of course, having to manually tune.

  6. KE5KCN

    KE5KCN Ham Member QRZ Page

    Just purchase an atbk-100 counterpose kit for the atas-120. The radials are already cut to lenght. If you want I have one that came with my 120, that I purchase off of ebay. I have no intention of using it a base, unless I took a trip and worked from a hotel balcony. As if the xyl would go for that. If you are interested in the counterpose kit email me ""
  7. N5USR

    N5USR Ham Member QRZ Page

    I haven't found the counterpoise kit sold by Yaesu to be worth a flip. You can have mine, if you come get it! :D (Besides, seems like it was for the higher bands anyway.)

    I have aluminum gutters on my house, attached an automotive L-bracket to the center of the gutter and mounted the ATAS on there. Cool, it worked! Getting it to tune on 40M was twitchy, it kept missing the dip so I had to tune it manually. But it worked.

    I'll also suggest putting up a dipole connected to a tuner. What I can hear with that is vastly superior to what the ATAS will do.

    And yes, you could use the ATAS with an 817 if you wanted to. The 817 won't auto-tune it, no, but MFJ sells a little box to go in the coax line with an up/down button on it to manually tune the antenna.
  8. G0GQK

    G0GQK Ham Member QRZ Page

    You are intending to use the antenna mobile and at home. Firstly you don't need a mile of wire to make all those counterpoise radials. Make a support for the antenna about 4-5 feet above earth, cut two quarter wave radials for each band and connect them to the ground on the antenna and place them as best you can 180 degrees apart for each band. feed the antenna five feet above ground with RG58 coax and put about six 12 inch coils in the coax at the feed point and see what happens. An antenna doesn't have to be 60 feet above earth to work, but it works better up there.

  9. A71AN

    A71AN QRZ Member

    My friend, ATAS-120 will work mobile with FT-857, but again like any screwdriver antenna, these ones are very sensitive and not a very good ones at all times, more over the might possibly tune on one band and not the other, I have give the big High Sierra 1800 with its all 8 legs redials and base, ok it did tune on 14 and 40 but thats it, never tuned on the other bands.

    I have tried tarheel Little II, that one was a disaster by all means as a mobile.

    I have also the ATAS-120 along with the FT-857 just the same story.

    Look to this my friend and think before you let your money go to the drain.

    I am now using some cheal mono band antennas for mobile and also using them for portable activities>

    40m, treid many time now and it is superb, all over QSL, Eu, State Side, Asia and Africa.

    30M is the same high quality signals receiving and sending.

    20M also the same

    17M just as good as the other ones.

    15M another great example of a cheap mono bander.

    10M tuning perfect to this band and managed to do many contacts.

    6 mono bands will cost 14 USA dollars and they are shipped to you from the state, which means you are not going to pay a lot like what I did for the postage.

    Remember screwdrivers, are so deligate and sensitive when you try to tune them, that due to many factors.

    I lost a lot of fun because of them while away from home, but enjoyed great QSO'S with those small cheap mono banders, they take less than 3 mints to change from one to another while the base is also small one and light and very accessable.

    The rest is your to decide my friend and wishing you all of the best
  10. W8XV

    W8XV Ham Member QRZ Page

    Check out this link.

    I set my 120A up a little different but with the same radial and made many contacts. The 857D worked great with this setup. I use this for camping and other outdoor activities.
  11. W4RLR

    W4RLR Premium Subscriber QRZ Page

    I've worked Belgium with my FT-100D and my ATAS-120, much to the amazement of my teenager and her friends who were in the truck at the time. Like any mobile antenna, or any antenna in general, it is a compromise.

    Go with the dipole. Cheap and effective, especially if you have a lot of trees to string wire from.
  12. W6GQ

    W6GQ Swap Meet Moderator QRZ Page

  13. WX7G

    WX7G Ham Member QRZ Page

    When ground mounting a mobile whip use several radials roughly the length of the whip antenna. An 8' whip needs radials out only 8'. Longer will help a bit but no much. Most of the current returning through GND is intercepted out about as far as the antenna is tall. I would use eight radials.

    If roof mounted two radials per band will do the job. L = 234/f. 32.7' for 40 meters, 16.5' for 20 meters, and so on.
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