Alpha Moto Mobile antenna

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

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  1. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Hey, I've looked at it before.

    Besides, anyone with a modicum of radio/electronics knowledge would injure themselves laughing after reading the advertising copy I have repeatedly quoted directly from their website.

    Again, I have no objection to the antenna, mostly because they make no performance (dB) claims. It appears to be the most compact and rugged mobile HF antenna I've seen! If it meets certain hams needs, great! I hope he sells tons of them.

    I just object to the inaccurate and misleading statements used to sell it.

    Let me retract my prior description of "Snake Oil" and charitably attribute the Alpha Antenna advertising copy to "Enthusiastic Exaggerations and Lack of Electronics Knowledge".

    I hope they will consider correcting their website. b.
     
    Last edited: Sep 25, 2014
  2. K0BG

    K0BG Ham Member QRZ Page

    Bill, check you PM file for more information.
     
  3. N0TES

    N0TES Ham Member QRZ Page

    Hi All - I can see everyone's points are very valid. I found it interesting that when I described how I actually designed the antenna, people refute it. That's ok, because I agree with KB4QAA when he said an accurate description of the Alpha MOTO would be:

    -Rugged
    -Compact
    -No extra whips
    -No adjustments required for band changes
    -No moving parts
    -No power required
    -No control interface boxes
    -On the air making contacts for an economical price!

    What an awesome way to describe the MOTO! I appreciate the recommendation KB4QAA gave for me to use the above for advertising! Besides, who really cares how I designed the antenna? So, I will remove my methods of design and replace it with the recommendation.

    I would also like to thank AD0AC and so many others who have helped encourage me, my employes, and my little company through the years!

    73s,

    Steve
    N0TES
     
  4. KH6AQ

    KH6AQ Ham Member QRZ Page

    The Moto mobile is an interesting antenna and it would be fun to take actual field strength measurements comparing it to a reference antenna.

    A NEC analysis at 7 MHz modeling what I think might be in the Moto mobile antenna, a Hamstick, a Tarheel 40A, and a 34' vertical. All antennas are mounted on perfect GND:

    Vertical +5 dBi
    Tarheel -2 dBi
    Hamstick -8 dBi
    Moto -36 dBi

    Modeling parameters:

    Moto
    1) 3.5' whip driven through a 1:9 transformer.
    2) Input terminated with a 200 ohm resistor to provide the 4:1 VSWR shown in the "independent analysis" at the Alpha website.

    Hamstick
    1) 7.5' antenna center loaded
    2) Inductor Q = 50

    Tarheel 40A
    1) 7.5' antenna loaded 20% up from the base
    2) Inductor Q = 200
     
  5. M3KXZ

    M3KXZ Ham Member QRZ Page

    Your whip length is wrong. It's 62" + the spring length. Not 41" (3'5").
     
  6. M3KXZ

    M3KXZ Ham Member QRZ Page

    Why are you only giving the 7MHz results of your modeling? It would be interesting to see the results (with the correct length whip of course) for the higher HF bands.
     
  7. N0TES

    N0TES Ham Member QRZ Page

    Why isn't your analysis comparing the antennas that were presented? Plus there is NO 1:9/9:1 used in the MOTO. Here are those antennas again in the attached image. The length of the whip in your MOTO analysis is almost half the length it actually is.
    73s,
    Steve
    N0TES
     

    Attached Files:

  8. KH6AQ

    KH6AQ Ham Member QRZ Page

    To refine my analysis I need to know what the circuit of the Moto is. Can you describe it in detail or post a schematic?

    If someone can lend me a Moto I will run field strength measurements of it and the two mobile antennas I have, a Hamtenna and a Tarheel 40A. Measurements can be performed on 40 and 20 meters.
     
    Last edited: Sep 28, 2014
  9. M3KXZ

    M3KXZ Ham Member QRZ Page

    David, also note what Steve says in the details on his store site:
    There is no claim of it being great on 40m, so why make comparisons on 40m?
     
  10. KH6AQ

    KH6AQ Ham Member QRZ Page

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