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NEWB question,, or just chattin

Discussion in 'CB Antennas' started by MadVeteran, Sep 25, 2021.

  1. MadVeteran

    MadVeteran Active Member

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    In the 70s, i had a 5/8 wave antenna. I seemed to have the biggest range of anyone around. today, i have an inverted v dipole at almost the same height (exact measurements not required for this theoretical chat).



    IF all things were equal, what approximate distance/reach difference would there be between antennas ?
    NOT looking for an engineered measured answer, just a 10-20 percent type educated guess... if thats possible.

    Now for the real theory type question,,, how many watts would be required to equal any difference (I know its not a linear gain,, I know its a diminishing return/gain when just pumping in watts but,, what would you guess) ?

    Every conversation with these questions in it seems to degrade into "you cant just add watts" ... etc. I KNOW. I just want to hear (and would really appreciate) what all of you experienced radio people have observed.

    Let the fun begin .... !

    PS - dont ban me,,, I am still curious.
     

  2. M0GVZ

    M0GVZ Sr. Member

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    You've two different antennas. The vertical one will give great performance on local contacts. The inverted V will be utterly crap for local contacts as it'll be horizontally polarised so will be as much as 20dB or almost 7 S points down on the vertical.

    However for DX things change a bit. Unfortunately to know by how much we'd need to know the approximate height of the dipole, i,e is it low down say 10ft, an average height of 20ft or 30ft high or more. So assuming it's the middle one, half wavelength up around 16 to 20ft. It will slap the crap out of the vertical up to around 4000 miles due to the fact that it not only will have gain over the vertical from the fact it's a dipole but also there will be ground reflected gain too which horizontal antennas benefit from. Above 4000 miles how high the dipole is will determine how it compares against the vertical. If it's 30ft up it'll likely be even stevens up to around 6000 miles. Once you get above that then unless that dipole is up around 609ft the vertical will be winning to the point you may not even hear the DX station on the dipole but when the dipole is up around 2 wavelengths high you also end up with a problem with nearby DX below a couple of thousand miles where the situation flips from what I said above for the sub 4000 mile distances and the vertical wins to the point it'll hear stations up to 2000 miles that the dipole doesn't even know are there. That I've experienced contesting where with a 10m beam up at 60ft I could work Pacific and Asia which were 7000-12000 miles away fantastic, with really strong signals but couldn't hear anything below 1200 miles at all. Dropped the antenna down to ~30ft and the situation reversed.
     
  3. MadVeteran

    MadVeteran Active Member

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    Thanks MOGVZ.
    I wonder if the inverted V (at approx 30 feet above ground) is why I am not getting much local talk. If I understand, are you thinking that inverted V is crap out to 20 miles ?
     
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  4. w9cll

    w9cll W9WDX Amateur Radio Club Member

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    You would be lucky to get five miles locally on an inverted v.
     
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  5. freecell

    freecell Well-Known Member

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    M0GVZ posted:
    "20dB or almost 7 S points...."

    6 dB. = 1 S Unit

    +60dB. = -13dB.
    +40dB. = -33dB.
    +20dB. = -53dB.
    9SUnit = -73dB.
    7SUnit = -85dB.
    5SUnit = -97dB.
    3SUnit = -109dB.
    1Sunit = -121dB.

    20 dB = 3.33 S Units.
     
  6. The DB

    The DB Sr. Member

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    Technically true, but this assumes that the s-meters on radios are in any way accurate. Apparently you haven't noticed, but on almost every radio out there, the s-meter reading is way off from what the actual measurement should be.

    If you judge by the meters on most radios, especially on the CB side of things, M0GVZ's numbers are more accurate than that list that no radio manufacturer actually bothers to follow in the first place...

    Even if we were talking some of the much more expensive ham radios that have been modified to work on CB (I'm not talking CB's that are sold as 10 meter radios, I'm talking about radios intended for use as ham radios), most of them are better, but still not up to the specs of your list.

    Come to think of it, it wasn't until about a decade or less ago that test equipment entered the hobby market that could accurately make said measurements, much less radios.

    That being said, I'm pretty sure that some of the newer ham radios do much better in this regard than any of the older radios from no more than a few years ago...


    The DB
     
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  7. MadVeteran

    MadVeteran Active Member

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    Would local chat be easier with the dipole in an L configuration ?
     
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  8. secret squirrel

    secret squirrel Lustrous Potentate

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    I run a bent L vertical dipole the lower leg is about 45 degrees from the ground as a base antenna, mounted to my shed at 16 feet to the mount. Its using two 7 foot Firesticks. I am sure there are better ways. No problems local, Can do skip with good conditions, Routinely 40 miles side band with local SSB net Sunday nights.

    https://www.bobscb.com/shop/product...ntenna-Stainless-Steel-Mobile-Antenna-Mounts/

    This is the mount I am using to make the dipole.
     
  9. MadVeteran

    MadVeteran Active Member

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    Very cool... Does the L cause directional preference or is it fully omni directional?
     
  10. secret squirrel

    secret squirrel Lustrous Potentate

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    On paper it is a little stronger toward the direction of the lower leg, but mostly omni directional. I just pointed it at the direction that I would talk the most.
     
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  11. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    upload_2021-10-21_21-16-6.png
    "L" antennas - Dowsing for RF...
    :sneaky::)(y)
     
  12. Rebel Outlaw

    Rebel Outlaw Well-Known Member

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    I don’t think many people taught about that:). I don’t know how you do it Andy; you do have some of the best replies period. :)(y):)(y):)(y)
     
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  13. Crawdad

    Crawdad Down in the mud invasive species

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    I have a wire inverted v (11 meter) with the feedpoint @ 1/2 wavelength. No trouble talking local 10 mi+ AM, 20+ SSB.

    Skip-wise SSB have made the UK, Caribbean, Central America, the left coast and lots of points in between. From Kentucky on 30 watts.

    For some reason I'm happy with the antenna.

    At my previous QTH I had a copper pipe horizontal dipole up 3/4 wavelength that I had zero issues with talking to AM locals on, even mobiles. One local was on a homebrew 1/4 wave vertical 17 miles away. Skip results were about the same as my current wire v.

    It always makes wonder if those who say you can't talk to local verticals on a v or horizontal have ever actually used one.
     
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  14. MadVeteran

    MadVeteran Active Member

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    You will laugh at this but, I have so little local traffic and, my wife is far too busy to bother helping do radio checks so,,, since I was getting concerned about inverted V local traffic i convinced myself I needed to test it myself.
    I took my 2Watt Walkie Talkie (rated at 4 Watts but tested at 2watts) ,, put it on a car antenna... Home CB attached to inverted V in attic ,,, TWO cell phones with active call between them,, one laying in front of home CB,, The other in car with me.
    - I drove approx 2.5 Miles / 4 KMs (measured in advance as the crow flies)
    - Spoke on the walkie Talkie (attached to K30 antenna) and listened on Cell phone. (I was not driving while conducting the test but, I could have used bluetooth to play Cell call over car speakers)

    I didnt even check any other distances. Local reception on inverted V seemed good. I was impressed 2 Watts did that well on a K30 in the suburbs (I was behind a building doing this test, not in a clearing).

    Difficult test to reverse in order to test transmission of inverted V but, if it can hear a weaker radio from smaller antenna, I am sure the V can talk to it also.

    One other note. If the inverted V is at all directional, I was on the weak side of that directional preference when doing this test.
     
    #14 MadVeteran, Oct 24, 2021
    Last edited: Oct 24, 2021
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  15. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    Looks like he is holding the stick too tight. Is that how its really done? I have to try it again.
     
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