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Lower SWR with 102 than 108

Discussion in 'CB Antennas' started by Captain Chaos, Oct 7, 2019.

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  1. Captain Chaos

    Captain Chaos New Member

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    I am getting a lower SWR with SS 102" whip (aprox. 1.3:1) than 108" (1.6:1) on 27.205
    I'm using HD stud mirrot mount on my semi. If I go down to 25.405 I get 1.2:1 with the SS 108" whip. Should I roll with the 108 or put the 102 back on?
    Sorry in advance for the newb question.


     

  2. undertaker

    undertaker Undertaker

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    102 ………...
     
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  3. Captain Chaos

    Captain Chaos New Member

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    What I don't understand then I thought 108 was what I should be running for 11m I thought 102 was too short without a spring.
     
  4. 2NC995

    2NC995 DAN

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    102 always worked for me.
     
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  5. Captain Chaos

    Captain Chaos New Member

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    102 with a 6inch spring or 102 with no spring
     
  6. 2NC995

    2NC995 DAN

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    No spring. However, I did have a fairly tall mount.

    I would go with whatever tunes better for your application. If the 102” is it, then you’re good.

    Aside from off-road vehicles or applications where the antenna needs to be tied down, I don’t like springs...especially on a 9’ long wet noodle.
     
  7. oldtymer

    oldtymer Well-Known Member

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    The higher you are in frequency the shorter the antenna -if you check 25.405 with the 102" it will be higher than the 108" because it is shorter.
     
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  8. Captain Chaos

    Captain Chaos New Member

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    So I should run the 102 for cb instead of the 108?
     
  9. 2NC995

    2NC995 DAN

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    Either run the 102” or start trimming the 108 until the SWR is where you want it.
     
  10. 357magnum

    357magnum Sr. Member

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    If the 102" works & you don't have a problem w/out the spring .... leave it alone . Just my 2 cents .;) 73 & God Bless , Leo BTW Welcome to the forum !(y)
     
  11. 2NC995

    2NC995 DAN

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    I’m not sure how folks come up with 108”, to be honest. I never remember hearing this in years past, but it seems like everyone talks about 108” now.

    Here’s a 1/4 wave calculator for you to play with. Assuming .956 as a generic velocity factor for stainless, I come up with 103.76”. Your 102” whip, plus your mounting stud, is probably very close to that. Sounds like you could be a hair longer, but definitely not six inches.

    https://m0ukd.com/calculators/quarter-wave-ground-plane-antenna-calculator/
     
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  12. Captain Chaos

    Captain Chaos New Member

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    Thanks for that info
     
  13. 2NC995

    2NC995 DAN

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    Well, there’s a good chance someone smarter will come along with more info, but in my opinion you’re not going to go wrong running the antenna with the lower SWR.
     
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  14. Woody-202

    Woody-202 Sr. Member

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    I've never been very picky when it came to mobile SWR as long as it was under 2:1 which ever SWR you don't want (1.3 or 1.6) send it to me. I'll take it.
     
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  15. 2NC995

    2NC995 DAN

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    Lol, You mean don’t chase those last few hundredths of a watt?
     
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