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Thread: Signstek Fm transmitter...using antenna that came with it...not too good so far

  1. #1
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    Default Signstek Fm transmitter...using antenna that came with it...not too good so far

    Got the signstek Fm transmitter and it comes with an antenna. Plugged in the cell phone streaming a radio station . Went to radio-locater.com and tried its suggestion for best channel...and also tried a few of the next best channels....not too good, even when the vehicle is feet away. I can only assume that it is the antenna.....So...do I have to make a dipole antenna instead?

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    Default Re: Signstek Fm transmitter...using antenna that came with it...not too good so far

    I would absolutely make a dipole antenna. The difference between the 2 is remarkable.

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    Default Re: Signstek Fm transmitter...using antenna that came with it...not too good so far

    Quote Originally Posted by Popo-B-Trippin View Post
    I would absolutely make a dipole antenna. The difference between the 2 is remarkable.
    You'll find complete instructions on how to do that in the Wiki on this site.

  4. #4
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    Default Re: Signstek Fm transmitter...using antenna that came with it...not too good so far

    When you measure the wire it says to start from the loop end. Does the loop figure into the measurement or should I start at the loop? Or am I just over thinking it?

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    Default Re: Signstek Fm transmitter...using antenna that came with it...not too good so far

    In my experience, It does not have to be exact... I've changed frequencies multiple times without an issue. So though I don't know the exact answer to your question (as it's been about 7 years since I built mine), I would say just ballpark it.

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    Default Re: Signstek Fm transmitter...using antenna that came with it...not too good so far

    Quote Originally Posted by Srmorgan View Post
    When you measure the wire it says to start from the loop end. Does the loop figure into the measurement or should I start at the loop? Or am I just over thinking it?
    The antenna length includes the loop.

  7. #7
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    Default Re: Signstek Fm transmitter...using antenna that came with it...not too good so far

    MikeKrebs, do you know what the impedance of the wiki dipole is? Is it 50 ohms? Should I use 50 ohm or 75 ohm coax?

  8. #8
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    Default Re: Signstek Fm transmitter...using antenna that came with it...not too good so far

    Quote Originally Posted by steve123 View Post
    MikeKrebs, do you know what the impedance of the wiki dipole is? Is it 50 ohms? Should I use 50 ohm or 75 ohm coax?
    If you are asking that question, I suspect you already know more than me.
    The wiki dipole article I found says to use television cable. That is likely 75ohm. If you look further, I think you will find places that argue less is better and you will find radio enthusiasts that generally want you to use 50 ohm. Maybe one of our ham radio operators can share their thoughts.

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    Default Re: Signstek Fm transmitter...using antenna that came with it...not too good so far

    You made me curious; so I googled and this came up near the top.

    https://forums.qrz.com/index.php?thr...ntenna.548333/

  10. #10
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    Default Re: Signstek Fm transmitter...using antenna that came with it...not too good so far

    Hmmm ... that is an interesting link. It appears to say that the impedance is dependant on the placement of the antenna above ground. What is not clear is the polarization. Do you know if the dipoles in the HAM guys use are vertical or horizontal? I think my take away is 75 ohms is likely pretty close. I think I have some 75 ohm cable lying around here somewhere. Thanks for posting the link!

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