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Modified Vector 4000

Discussion in 'CB Antennas' started by bob85, Oct 3, 2009.

  1. HomerBB

    HomerBB Sr. Member

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    At 27.2' the .82^ would be 28.22' long overall length.
    I don't know how long it actually is without looking back in the thread.


     

  2. bob85

    bob85 Supporting Member

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    Eddie,

    Vortex claimed the q82 mk1 was consistently 2 s-units up on a vector 4000,
    can you see that been true even on the most generous cb s-meter unless other factors were messing the test up ?

    I have handled & had a look at a q82mk1,
    my local buddy swapped from a new v4k that got smashed up in wind to the q82 on his gateway,

    i see nothing in the construction that would make it perform much different to a new vector 4000 and i don't see it on air either,

    q82 monopole is similar diameter with one tube size fatter radials & one tube size fatter teflon gamma,

    im not casting my vote for the 3/8 cone until i test both versions at the same time,
    i have to be sure i can replicate the results,

    the difference i did see is so great that i can't see how it can be true unless other factors are causing the difference,

    we are talking about 3.6dBm increase from the same monopole in the same place with the only difference been the radial length & gamma settings,

    I just cleaned another set of tubes & other parts to ensure theres no possible bad or higher resistance connections anywhere,

    don't scrap the model before i redo the test.
     
  3. bob85

    bob85 Supporting Member

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    The .82wave came from Donalds website along with the other claims Vortex made when they brought the first q82 out. they did get coNfuffled with dBi & dBd
     
  4. The DB

    The DB Sr. Member

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    Just so you are aware...

    Apples.

    Oranges.

    I would be very surprised if these were to line up, or even come close, and even if they did it would be more or less a coincidence than anything. I just wish I noticed back when this was one of the big sticking points between you and Shockwave back in the day.

    In one case, you have an antenna pattern that can forms wavelengths, and in some cases miles depending on the situation, away from the antenna, and in the other you are measuring at a specific point, generally before such pattern will form, and also often at horizontal or below the actual antenna where the modeling software shows no actual data. Both are accurate ways of determining an antennas gain, but in two very different situations that are nothing alike, and at best barely related.

    Its like trying to compare a device that uses a laser to measure the distance between two walls, and a laser to measure the speed of a car. They both use lasers, but they tell you very different things.


    The DB
     
    bob85 likes this.
  5. freecell

    freecell Member

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    "we are talking about 3.6dBm increase...."

    is this 3.6 dBm increase equal to 2.290 mW or (-3.6 dBm) 0.436 mW ?
    does anyone here seriously believe that 2.290 mW or 0.436 mW is worth
    all this trouble? you're just spinning your wheels.
     
    #755 freecell, Jan 10, 2021
    Last edited: Jan 10, 2021
    Marconi likes this.
  6. bob85

    bob85 Supporting Member

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    None of the above,
    its a change from -89.7dBm to -86.1dBm

    -3.6dBm is a massive signal, 3.6dBm & the back to back diodes are conducting hard
     
    Marconi likes this.
  7. freecell

    freecell Member

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    "-3.6dBm is a massive signal...."

    no, it isn't. enter either -3.6 or 3.6 into the appropriate field and
    convert. the amount of power represented by those values and
    / or any changes are reflected in the output. reset and try again.

    https://www.rapidtables.com/electric/dBm.html#dBm_to_Calculator
     
    #757 freecell, Jan 10, 2021
    Last edited: Jan 10, 2021
  8. bob85

    bob85 Supporting Member

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    first test without radials,

    -89.7dBm about 1070 femtowatts or 1.07picowatts with 1/4wave cone,

    increasing to

    -86.1dBm about 2455 femtowatts or 2.455 picowatts with 3/8wave cone

    giving a change of 1385 femtowatts or 1.385 pico watt or according to the sdr 3.6dBm
    measured at the AD converter in the sdr im using.
     
  9. freecell

    freecell Member

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    #759 freecell, Jan 10, 2021
    Last edited: Jan 10, 2021
    Marconi likes this.
  10. Shockwave

    Shockwave Sr. Member

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    When I look at the first model of the Vortex MKI below, that is supposed to be similar to the Vector 4K, I see that the cone is either not a full 1/4 wave or the main radiator is longer than normal. Notice the amount of out of phase energy being radiated into the pattern from the monopole just above the cone. The Vector has the top of the cone loop, in exact alignment with the place on the main radiator where the phase crossover takes place.

    https://www.vortexantennas.co.uk/wp-content/uploads/q82_mk1_data-1.jpg

    When we look at the Vortex MKII shown below, that cone is longer than 1/4 wave and is also covering over a small portion of the in phase radiation from the central monopole. They have also lowered the frequency of the source by 150 Khz. which could exaggerate these phase changes.

    http://www.vortexantennas.co.uk/wp-content/uploads/q82_mk11_data-1.jpg

    While the length of the cone and central monopole have been modified with several different designs over the years, I've always noticed a peak in gain on the horizon occurs, when the ring of the cone is in alignment with the phase crossover point on the main radiator. As Bob mentioned in the Vortex thread, when going beyond 1/4 wavelength cone radials, gain starts to drop. Just like Bob, I think I stopped short of adding another 1/8 wavelength to the cone.

    Therefore, I cannot personally attest to the possibility that continuing to add more length, to the 3/8 wavelength point, could begin to reverse the effect and add gain. However, I see nothing constructive happening in the phase relationship between the cone and monopole, until the cone is extended to a 1/2 wave, with a full wave monopole inside.

    Then we have alignment of the ring with the new 1/2 wave, phase crossover point on the main radiator once again. Didn't Vortex experiment with a model like this at one point? The only reason I never tried the 1/2 wave over a 1/2 wave cone was I have no confidence that the end fed 1/2 wave cone, with a very high feedpoint impedance, would have any ability to effectively bleed off CMC. Incidentally, neither Vortex model shows what's happening on a mast or feedline for comparison.
     
  11. nav2010

    nav2010 Active Member

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    Not strictly true. It's an open sleeve design similar to a folded dipole in electrical operation. They are not strictly radials but more like the shorter tuning stub on a J-pole but with more complex current and voltage patterns.
     
    HomerBB likes this.
  12. nav2010

    nav2010 Active Member

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    Unless of course the antenna uses the top 1/8th wave of the basket in phase with the 3/8ths wave monopole leaving a quarter wave basket again below the phase crossover point.
     
  13. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

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    Bob think you hit this on the head. The Vector is a thing of the past.

    I haven't got all the kinks ironed out. as you will see below, but you can get this information and dimensions out to us as soon as you confirm this gold mine of an antenna.

    Thanks for your persistence in testing this antenna. Put a few solid brackets for those spindly radials and get it up to about 50' feet and your buddies will swear you have a beam pointed right at em'.(y)

    BTW, I'd put 4 or more 108" horizontal radials right below the feed point, so we can get a better ground.

    It also has a 6.5 MHz bandwidth for <2.00:1 SWR

    Ignore the mis-match and the bad Average Gain, a good gamma tune will easily take care all those problems, or get a good auto tuner.
     

    Attached Files:

    #763 Marconi, Jan 10, 2021
    Last edited: Jan 10, 2021
  14. bob85

    bob85 Supporting Member

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    Donald
    i don't recall Vortex using a longer monopole with the 3/8wave cone,
    The mk1 is based on your dominator,

    im not going to worry too much about what's going on until i do another test and still see an advantage,


    Eddie
    your segment lengths are not equal, even i know that just aint right.
     
  15. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

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    I'm going to model the M1 too. I believe it is possibly a sleeper too.

    Your ideas have convinced me, and for sure when I got my model to show the same gain as Vortex advertised. I think we have winner Bob.

    CB'er are gonna love this line of vertical antenna. Maybe Vortex closed down until the China virus scare is over...and so they could build up a good supply of these great super CB antennas.

    Good work Bob, you did it again.
     

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