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Thread: Antenna length?

  1. #1
    RC Qualifier
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    Antenna length?

    Hey guys, my antenna got messed up the other day and I bought a replacement antenna wire, only problem is I'm not entirely sure how long to make it exactly...

    Anyone know the stock antenna length?
    If not I'm going with 20" because that how long I want to remember it being...
    $1400 Nitro Rustler and counting :D

  2. #2
    RC Turnbuckle Jr.
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    20 inches sounds about right, I'm not sure what the stock length is either.
    It's a Jeep thing, you wouldn't understand.

  3. #3
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    20"? I don't think its that long but i might be wrong
    this is a accectable signature?????

  4. #4
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    go measure your antenna JshBetz, or even just your antenna tube, then add length for from the receiver to the tube...then there is always a little bit sticking out the top....I went with 22" because its easier to cut something shorter then cutting it longer...
    $1400 Nitro Rustler and counting :D

  5. #5
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    just measured one of mine and its 22" from the box to the end of the wire
    if it aint broke dont fix it...need bigger ramp

  6. #6
    RC Turnbuckle Jr.
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    I seem to remember 24" being the stock length.
    It's important to get it right.
    An antennae is cut to length depending on the frequency being transmitted.
    It needs what's called a "standing wave".

  7. #7
    RC Turnbuckle Jr.
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    Lambda equals velocity over frequency, so..

    Velocity = 186,400 miles per second (or 984x10 to the 6th ft./sec)

    Frequency = 27 MHz

    I found your formula.
    Do the math.

    You need Lambda (also known as the length of your antennae).
    I don't have a calculator next to me.

  8. #8
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    I don't have a calculator next to me.
    You do, its your computer. lol

  9. #9
    RC Turnbuckle Jr.
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    Not where I was at.

    I'm home from work now and have a calculator.
    I used inches for velocity. That's 11.8 times 10 to the 9th.
    [Photons and Electrons travel at the cosmic speed limit]

    The answer is 437 inches (36.444444444444444444444444444444 feet)..

    Since we know for sure our antennaes are not 36 feet long, they used a ratio of Lambda to cut the length of antennae.
    Half lambda is 218 (and some change), half again is 109, half again is 54, and half again is 27.3 inches.

    You can cut it in halves like that and still have a good standing wave. (with sacrifices, but I won't get into all of the theory)

    I'd cut my antennae at 27.3 inches.

    I knew I'd get some use out of my degree in electronics.
    I don't get to use it often enough at work. (at least not the communications stuff)


    EDIT: I just found a stock Traxxas receiver in my garage. It had a frayed end on it (maybe lost a little of it), but it measured 25 and a quarter inches.
    I forgot to take into consideration at least a 5% loss. That should have been subtracted from my antennae length.
    Taking 5% (1.36 inches) off would make it 26 inches.
    That's my final answer, Regis. Cut it there.
    Last edited by jrfink; 09-29-2007 at 10:28 AM.

  10. #10
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    So you do learn something new everyday, and I just woke up! now I don't have to learn anything new for the rest of the day

    I measured the length of the peices I had and added an extra 2 inches and got 22"...Traxxas might not always make them the same length


    Next big mod for my NR: 9 foot whip antenna (I'll be able to see it for miles)

    ...I'm also going to boost the output on my transmitter so the antenna has something to pick up....
    $1400 Nitro Rustler and counting :D

  11. #11
    RC Turnbuckle Jr.
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    Yeah, you're probably right. I found a couple other stockers and they all measure different lengths.
    It will still work for our purposes, but isn't the best it could be. You won't have range problems with your antennae.

    Let's put it this way... If I were to design the transmission lines for a local AM radio station, I'd want my Marconi to be exactly the correct length.

  12. #12
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    Hi. I realize this a really old post, but if you're still around I was wondering if you ever hooked up the whip antenna and / or increased the transmitter power? Wanting to do the same thing here.

    -----------
    Next big mod for my NR: 9 foot whip antenna (I'll be able to see it for miles)

    ...I'm also going to boost the output on my transmitter so the antenna has something to pick up....[/QUOTE]

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