Doublet with ladder line vs coax w.r.t. noise












2












$begingroup$


I live in the city, with 50’x 100’ lots. I use an 80 meter doublet at 30 feet, fed with ladder line to a tuner. My noise floor ranges from S5 to S9 depending on the time.



Would a coax feed reduce the noise level, while eliminating my ability to tune all the HF bands? Or is this just the nature of city living and the HF bands? I tried a loop antenna and it actually has more noise! I miss the suburbs for my ham radio hobby!






dipole feed-line noise







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  • $begingroup$
    The answer might depend on the noise generator and its location. Please describe the noise; is it atmospheric static or is it produced by devices like TVs, wall-warts and modems?
    $endgroup$
    – Brian K1LI
    15 hours ago
















2












$begingroup$


I live in the city, with 50’x 100’ lots. I use an 80 meter doublet at 30 feet, fed with ladder line to a tuner. My noise floor ranges from S5 to S9 depending on the time.



Would a coax feed reduce the noise level, while eliminating my ability to tune all the HF bands? Or is this just the nature of city living and the HF bands? I tried a loop antenna and it actually has more noise! I miss the suburbs for my ham radio hobby!






dipole feed-line noise







share|improve this question









New contributor




Steve is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$












  • $begingroup$
    The answer might depend on the noise generator and its location. Please describe the noise; is it atmospheric static or is it produced by devices like TVs, wall-warts and modems?
    $endgroup$
    – Brian K1LI
    15 hours ago














2












2








2





$begingroup$


I live in the city, with 50’x 100’ lots. I use an 80 meter doublet at 30 feet, fed with ladder line to a tuner. My noise floor ranges from S5 to S9 depending on the time.



Would a coax feed reduce the noise level, while eliminating my ability to tune all the HF bands? Or is this just the nature of city living and the HF bands? I tried a loop antenna and it actually has more noise! I miss the suburbs for my ham radio hobby!






dipole feed-line noise







share|improve this question









New contributor




Steve is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$




I live in the city, with 50’x 100’ lots. I use an 80 meter doublet at 30 feet, fed with ladder line to a tuner. My noise floor ranges from S5 to S9 depending on the time.



Would a coax feed reduce the noise level, while eliminating my ability to tune all the HF bands? Or is this just the nature of city living and the HF bands? I tried a loop antenna and it actually has more noise! I miss the suburbs for my ham radio hobby!






dipole feed-line noise




dipole feed-line noise






share|improve this question









New contributor




Steve is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question









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Steve is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









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edited 11 hours ago









Marcus Müller

7,7031031




7,7031031






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asked 15 hours ago









SteveSteve

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111




New contributor




Steve is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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Steve is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Steve is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












  • $begingroup$
    The answer might depend on the noise generator and its location. Please describe the noise; is it atmospheric static or is it produced by devices like TVs, wall-warts and modems?
    $endgroup$
    – Brian K1LI
    15 hours ago


















  • $begingroup$
    The answer might depend on the noise generator and its location. Please describe the noise; is it atmospheric static or is it produced by devices like TVs, wall-warts and modems?
    $endgroup$
    – Brian K1LI
    15 hours ago
















$begingroup$
The answer might depend on the noise generator and its location. Please describe the noise; is it atmospheric static or is it produced by devices like TVs, wall-warts and modems?
$endgroup$
– Brian K1LI
15 hours ago




$begingroup$
The answer might depend on the noise generator and its location. Please describe the noise; is it atmospheric static or is it produced by devices like TVs, wall-warts and modems?
$endgroup$
– Brian K1LI
15 hours ago










2 Answers
2






active

oldest

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2












$begingroup$

No, coax wouldn't be expected to improve the noise, unless your ladder line is running very close (within 1-2 times its conductor spacing) to a specific noise source, in which case you would be better off fixing that by finding a way to provide better spacing. The only thing that will change with coax is that your losses will become quite a bit higher, and more of your transmit power will be spent on heating the coax instead of making radio waves, especially when operating the doublet far away from a match with the coax.






share|improve this answer









$endgroup$













  • $begingroup$
    Agreed. And, unless specific steps are taken, coax shield can be a very effective "antenna" to pickup noise.
    $endgroup$
    – Brian K1LI
    15 hours ago



















2












$begingroup$

There are a few things to think about.



Coaxial cable will likely not have a positive impact on your RFI.



Unfortunately, urban locations are loaded with RFI. Antenna direction and distance are the primary ways of reducing the received noise. On a small lot, this is not always possible but improvements should at least be evaluated. For example, an electrically shortened antenna may allow the antenna to be located further away from local noise sources and oriented such that its directionality attenuates these noises.



Don't overlook the opportunity to identify and potentially eliminate noise sources. Start with your own house by powering your radio off of a battery and shutting down the house power and other battery powered devices within the house. If the noise level drops, start turning on individual breakers to help identify the sources of your local noise. Go RFI hunting in the neighborhood to identify other noise sources that might be correctable.



If the antenna is not well balanced due to factors such as uneven heights or trees or buildings near the antenna then the feedline can become unbalanced and be a point of ingress for noise. A 1:1 balun at the feedpoint may help mitigate the noise ingress.



Connecting a balanced feedline to an unbalanced tuner can also couple local RFI into the antenna system. The antenna side of an unbalanced tuner should have a 1:1 balun between it and the balanced line. A belts and suspenders approach is to also put a 1:1 balun on the coaxial side of the tuner going to the transceiver.






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    2 Answers
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    2 Answers
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    $begingroup$

    No, coax wouldn't be expected to improve the noise, unless your ladder line is running very close (within 1-2 times its conductor spacing) to a specific noise source, in which case you would be better off fixing that by finding a way to provide better spacing. The only thing that will change with coax is that your losses will become quite a bit higher, and more of your transmit power will be spent on heating the coax instead of making radio waves, especially when operating the doublet far away from a match with the coax.






    share|improve this answer









    $endgroup$













    • $begingroup$
      Agreed. And, unless specific steps are taken, coax shield can be a very effective "antenna" to pickup noise.
      $endgroup$
      – Brian K1LI
      15 hours ago
















    2












    $begingroup$

    No, coax wouldn't be expected to improve the noise, unless your ladder line is running very close (within 1-2 times its conductor spacing) to a specific noise source, in which case you would be better off fixing that by finding a way to provide better spacing. The only thing that will change with coax is that your losses will become quite a bit higher, and more of your transmit power will be spent on heating the coax instead of making radio waves, especially when operating the doublet far away from a match with the coax.






    share|improve this answer









    $endgroup$













    • $begingroup$
      Agreed. And, unless specific steps are taken, coax shield can be a very effective "antenna" to pickup noise.
      $endgroup$
      – Brian K1LI
      15 hours ago














    2












    2








    2





    $begingroup$

    No, coax wouldn't be expected to improve the noise, unless your ladder line is running very close (within 1-2 times its conductor spacing) to a specific noise source, in which case you would be better off fixing that by finding a way to provide better spacing. The only thing that will change with coax is that your losses will become quite a bit higher, and more of your transmit power will be spent on heating the coax instead of making radio waves, especially when operating the doublet far away from a match with the coax.






    share|improve this answer









    $endgroup$



    No, coax wouldn't be expected to improve the noise, unless your ladder line is running very close (within 1-2 times its conductor spacing) to a specific noise source, in which case you would be better off fixing that by finding a way to provide better spacing. The only thing that will change with coax is that your losses will become quite a bit higher, and more of your transmit power will be spent on heating the coax instead of making radio waves, especially when operating the doublet far away from a match with the coax.







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered 15 hours ago









    hobbs - KC2Ghobbs - KC2G

    75028




    75028












    • $begingroup$
      Agreed. And, unless specific steps are taken, coax shield can be a very effective "antenna" to pickup noise.
      $endgroup$
      – Brian K1LI
      15 hours ago


















    • $begingroup$
      Agreed. And, unless specific steps are taken, coax shield can be a very effective "antenna" to pickup noise.
      $endgroup$
      – Brian K1LI
      15 hours ago
















    $begingroup$
    Agreed. And, unless specific steps are taken, coax shield can be a very effective "antenna" to pickup noise.
    $endgroup$
    – Brian K1LI
    15 hours ago




    $begingroup$
    Agreed. And, unless specific steps are taken, coax shield can be a very effective "antenna" to pickup noise.
    $endgroup$
    – Brian K1LI
    15 hours ago











    2












    $begingroup$

    There are a few things to think about.



    Coaxial cable will likely not have a positive impact on your RFI.



    Unfortunately, urban locations are loaded with RFI. Antenna direction and distance are the primary ways of reducing the received noise. On a small lot, this is not always possible but improvements should at least be evaluated. For example, an electrically shortened antenna may allow the antenna to be located further away from local noise sources and oriented such that its directionality attenuates these noises.



    Don't overlook the opportunity to identify and potentially eliminate noise sources. Start with your own house by powering your radio off of a battery and shutting down the house power and other battery powered devices within the house. If the noise level drops, start turning on individual breakers to help identify the sources of your local noise. Go RFI hunting in the neighborhood to identify other noise sources that might be correctable.



    If the antenna is not well balanced due to factors such as uneven heights or trees or buildings near the antenna then the feedline can become unbalanced and be a point of ingress for noise. A 1:1 balun at the feedpoint may help mitigate the noise ingress.



    Connecting a balanced feedline to an unbalanced tuner can also couple local RFI into the antenna system. The antenna side of an unbalanced tuner should have a 1:1 balun between it and the balanced line. A belts and suspenders approach is to also put a 1:1 balun on the coaxial side of the tuner going to the transceiver.






    share|improve this answer











    $endgroup$


















      2












      $begingroup$

      There are a few things to think about.



      Coaxial cable will likely not have a positive impact on your RFI.



      Unfortunately, urban locations are loaded with RFI. Antenna direction and distance are the primary ways of reducing the received noise. On a small lot, this is not always possible but improvements should at least be evaluated. For example, an electrically shortened antenna may allow the antenna to be located further away from local noise sources and oriented such that its directionality attenuates these noises.



      Don't overlook the opportunity to identify and potentially eliminate noise sources. Start with your own house by powering your radio off of a battery and shutting down the house power and other battery powered devices within the house. If the noise level drops, start turning on individual breakers to help identify the sources of your local noise. Go RFI hunting in the neighborhood to identify other noise sources that might be correctable.



      If the antenna is not well balanced due to factors such as uneven heights or trees or buildings near the antenna then the feedline can become unbalanced and be a point of ingress for noise. A 1:1 balun at the feedpoint may help mitigate the noise ingress.



      Connecting a balanced feedline to an unbalanced tuner can also couple local RFI into the antenna system. The antenna side of an unbalanced tuner should have a 1:1 balun between it and the balanced line. A belts and suspenders approach is to also put a 1:1 balun on the coaxial side of the tuner going to the transceiver.






      share|improve this answer











      $endgroup$
















        2












        2








        2





        $begingroup$

        There are a few things to think about.



        Coaxial cable will likely not have a positive impact on your RFI.



        Unfortunately, urban locations are loaded with RFI. Antenna direction and distance are the primary ways of reducing the received noise. On a small lot, this is not always possible but improvements should at least be evaluated. For example, an electrically shortened antenna may allow the antenna to be located further away from local noise sources and oriented such that its directionality attenuates these noises.



        Don't overlook the opportunity to identify and potentially eliminate noise sources. Start with your own house by powering your radio off of a battery and shutting down the house power and other battery powered devices within the house. If the noise level drops, start turning on individual breakers to help identify the sources of your local noise. Go RFI hunting in the neighborhood to identify other noise sources that might be correctable.



        If the antenna is not well balanced due to factors such as uneven heights or trees or buildings near the antenna then the feedline can become unbalanced and be a point of ingress for noise. A 1:1 balun at the feedpoint may help mitigate the noise ingress.



        Connecting a balanced feedline to an unbalanced tuner can also couple local RFI into the antenna system. The antenna side of an unbalanced tuner should have a 1:1 balun between it and the balanced line. A belts and suspenders approach is to also put a 1:1 balun on the coaxial side of the tuner going to the transceiver.






        share|improve this answer











        $endgroup$



        There are a few things to think about.



        Coaxial cable will likely not have a positive impact on your RFI.



        Unfortunately, urban locations are loaded with RFI. Antenna direction and distance are the primary ways of reducing the received noise. On a small lot, this is not always possible but improvements should at least be evaluated. For example, an electrically shortened antenna may allow the antenna to be located further away from local noise sources and oriented such that its directionality attenuates these noises.



        Don't overlook the opportunity to identify and potentially eliminate noise sources. Start with your own house by powering your radio off of a battery and shutting down the house power and other battery powered devices within the house. If the noise level drops, start turning on individual breakers to help identify the sources of your local noise. Go RFI hunting in the neighborhood to identify other noise sources that might be correctable.



        If the antenna is not well balanced due to factors such as uneven heights or trees or buildings near the antenna then the feedline can become unbalanced and be a point of ingress for noise. A 1:1 balun at the feedpoint may help mitigate the noise ingress.



        Connecting a balanced feedline to an unbalanced tuner can also couple local RFI into the antenna system. The antenna side of an unbalanced tuner should have a 1:1 balun between it and the balanced line. A belts and suspenders approach is to also put a 1:1 balun on the coaxial side of the tuner going to the transceiver.







        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited 11 hours ago

























        answered 13 hours ago









        Glenn W9IQGlenn W9IQ

        16.3k11146




        16.3k11146






















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