Alpha Moto Mobile antenna

Discussion in 'Mobile Radio Systems' started by ZL1MHS, Sep 22, 2014.

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  1. KH6AQ

    KH6AQ Ham Member QRZ Page

    What bands does the Alpha Moto cover?

    This video says the Alpha Moto will work on 80-10 meters.
    http://www.youtube.com/watch?v=Tis-knhuOLg

    This add says the Alpha Moto will work on 6-40 meters.
    http://www.ebay.com/itm/Alpha-MOTO-...enna-Available-with-80M-Receive-/121136767363

    This link says "Alpha MOTO 6-40 Meters rated 500 Watts is tunable on 60-80 Meter [sic]."
    http://alphaantenna.com/pdf/Alpha_Antenna_MOTO_User_Guide.pdf

    The Alpha MOTO User Guide says 6-40 meters on page 1 and 3.5 to 54 MHz on page 2.

    On page 4 of the User Guide the SWR by band is shown. The 1.4:1 VSWR on 6 meters and the 5 foot whip point to a directly fed antenna, with or without a shunt resistor. The approximately 5:1 to 7:1 VSWR numbers for 40 through 10 meters point to some sort of lossy network.

    Might the Alpha Match connect the coax directly to the whip with a shunt resistor across the coax?

    The complex impedance data is difficult doesn't help much because the length of coax is not stated.
    http://www.alphaantenna.com/tech/Independent-Testing/MOTO/

    The User Guide says to use an antenna tuner. The majority of modern HF transceiver internal antenna tuners are specified to tune up to a 3:1 VSWR. So, they cannot be relied on to tune the Alpha MOTO with its 5:1 to 7:1 VSWR (40 through 10 meters).


     
    Last edited: Sep 28, 2014
  2. N0TES

    N0TES Ham Member QRZ Page

    The MOTO is 6-40M transceive and 60-80M receive.


    Please let me know if the following information helps, which I've taken directly from https://amateurradiostore.com/all-a...-meter-p-292?zenid=atab1j05k2vtct5pkri75368a4


    "QUICK INTRODUCTION - Just attach your antenna tuner to the indestructible MILITARY MOBILE grade 6-40 Meter 500 Watt Alpha MOTO Antenna. This will allow you to tune then transmit and receive on 6-40 meters while driving down the highway or parked in your favorite spot for HF operations. An added bonus, you can also tune 60 & 80 Meters so you can listen in on your favorite nets or just pass the time listening to QSOs. Remember to purchase the optional Alpha Jam Mount less you already have a mount. From the owner; "This antenna works very well with any tuner on 6, 10, 12, 15, 17, & 20 meters. On 30 it still works pretty well and you'll even make some decent state-side contacts on 40 meters. On 60 & 80 meters, it's a receive only antenna, although contacts have been logged. Just remember to place it as high as possible on your vehicle and use a mount that is as good as the Alpha Jam mount." "

    Bottom line is that I'm just offering an alternative choice for a mobile antenna. So as far as how I designed it or how it is designed, that information was removed from my web site yesterday by the suggestion of another ham.

    73s,

    Steve
    N0TES
     
    Last edited: Sep 28, 2014
  3. W5TTW

    W5TTW XML Subscriber QRZ Page

    My Alpha Moto mobile antenna has replaced multiple hamsticks that were a pain to swap on long trips. The antenna works very well on 6-20. I haven't had as much success on 40 as I would like, but I didn't expect much due to the length of the whip. (I may replace it with something longer.)

    It never ceases to amaze me how some ops will criticize gear that they have never tried. I'm very happy with my "snake oil dummy load" antenna.
     
  4. KH6AQ

    KH6AQ Ham Member QRZ Page

    W5TTW, what transceiver are you using and does its internal autotuner tune the MOTO on 40-6 meters?
     
  5. K0BG

    K0BG Ham Member QRZ Page

    One thing we all have to realize, that almost anything will work to some degree. If you have propagation, and not too much interference, it only takes about 10 milliwatts to circle the globe. A good real-world example is 80 meters. A typical 80 meter mobile antenna will be about 1% efficient. Yes, if you get a big ugly one, with a huge cap hat, you might get 6%. Yet, one watt out is enough to work the world, when conditions are good. These are the reasons you see so many folks file reports on their antennas using words to the effect.... It works well. Or, I worked 5 DX stations with it the first day! None of this palaver means much. And, it doesn't matter if you can hear the other station. What really counts, is whether the other station can hear you!

    The difference between the antennas described above by David, WX7G, is very close to real world numbers. What he didn't publish was the average noise floor of any given band. If your signal is below that level, you're not going to hear anyone, and no one will be able to hear you. If any one person is satisfied with that, great! I for one, am not. This is the reason I do not scrimp antenna wise. It is, after all, the antenna which sets the lowest common denominator.
     
  6. W5TTW

    W5TTW XML Subscriber QRZ Page

    I use the Alpha Moto with the FT857D and LDG Z11 auto tuner.
     
  7. W5TTW

    W5TTW XML Subscriber QRZ Page

    I understand what you are saying, but (happily)working multiband mobile with a single antenna isn't easy. The choices of unsightly commercial antennas is limited. If the Alpha Moto was junk, I'd use something else.
     
  8. K0BG

    K0BG Ham Member QRZ Page

    Paul, just as important is the length of coax cable between the antenna and the tuner, especially so if you're using RG58. If the length is say 10 feet, and the SWR is 5:1, the losses through the tuner and the coax cable is well over half the input power. Will 3 or 4 dB doesn't sound like much numerically, it reality it is. So give David the lengths (he loves to do the math), and he'll give you an idea of how much radiated power you really have.
     
  9. W5TTW

    W5TTW XML Subscriber QRZ Page

    Alan, the only thing that's important to me is if I'm making good contacts. Other than the poor performance on 40, it works very well. I have two mounts on my truck and I've done some A/B testing switching from hamsticks to the Alpha. (I even swapped the antenna locations.) No discernible difference on either end of the QSO.

    I know there are losses but it doesn't seem to impair my ability to work who I hear or receive great signal reports while mobile. I'm not going to replace it with something that looks better on paper. I'm very happy with the product.
     
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