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MACO VQ3

Discussion in 'Amateur Radio Antennas' started by Mudfoot, May 3, 2019.

  1. lonestarbandit

    lonestarbandit 4-2-9 Central TX

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    So applying all of this and turning their dbi rating into dbd in theory with assumption of 100% efficiency and 0 loss (neither of which is obviously real world) this VQ3 will have 6.77 dbd of gain... So in reality I should expect around 5.5 to 6 dbd or somewhere in between a 3 and 4 element traditional yagi? This falls within my realm of original expectation for the antenna so I feel slightly better now, though in retrospect probably should have gone with the Siro 27-4 for 1/3 the money and potentially similar performance but I was worried about weight. Of course having gone from the VQ2 to now VQ3 both boom length and weight has jumped up to the point the Siro probably would have been lighter. Too late now I already special ordered so will have to go with it.
    Thanks for all this explanation, as I say, new to the beam game.


     
    #31 lonestarbandit, Jun 21, 2021
    Last edited: Jun 21, 2021
    Crawdad likes this.

  2. Justme

    Justme Sr. Member

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    6dBd still not to be snuffed at, a beam will give gain receive and transmit, and if the band is busy you can use the beam to attenuate an offending station on the same frequency.
    Amplifiers are nice, give some clout but don't improve receive, don't use pre amplifiers in the radio's or amplifiers they mostly enhance more noise.
    The beam will add 1 S point noise free gain in receive, best of all worlds.
    Opening angle is large enough to hit stations, and use backside to attenuate other stations on that channel you are on to work that DX you are after.
    Use good coax and connectors specially if you need long lengths.
    And enjoy the beam ;)
     
  3. Crawdad

    Crawdad Down in the mud invasive species

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    Now that's funny right there
     
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  4. lonestarbandit

    lonestarbandit 4-2-9 Central TX

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    Well, I will have this eventually, plus about 800 CB glory watts aka peak amp I already have. Though in fairness, if we move to AVG the way I drive it, that would be 250-300 AVG . Delibrately had it buit with B bias and no preamp. I am hoping those two items together will do what I want within reason. There's no way on my location to run a 8 element beam like ole Needlebender out of Florida which hypothetically I "want" lol.
    I'm also within a couple miles of an airport so doubling amp size is asking for trouble, I'm probably already too big there as is.
     
    #34 lonestarbandit, Jun 21, 2021
    Last edited: Jun 21, 2021
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  5. The20poundhammer

    The20poundhammer Sr. Member

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    Last night i worked a station in New Brunswick that was running the VQ3 and he was doing a great job with it. I asked him how he liked it and he said he really loved it. Said he was on a 7300 with about 80 watts and was booming in.
     
  6. Justme

    Justme Sr. Member

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    I run my HEathkit SB-1000 at mostly 700 to 800 watts keeping it clean and healthy, did a full rebuild of that one including new 3-500 ZG tube.
    Use low pass filter if you are close to an airfield to supress 5th harmonic in the airband ...
    Running 300 watts and 6 dB gain is 1200 watts ERP.
    I hope it works fine there for your station, and you have tons of fun with it.
     
  7. The DB

    The DB Sr. Member

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    A little more about gain and the various ways of measuring gain.

    A lot of people believe that dBd is a more relevant comparison for various reasons. The thing is, as mentioned above by Freecell, antenna gain is determined by factoring in directivity and loss as compared to no directivity and no loss. The concept of dBi is a radiator with no directivity and no loss, so it is the ultimate theoretical baseline.

    Many people think of dBd as the antenna in their back yard, and thus think it is more relevant than dBi as a baseline source. Unfortunately, this is based on a misunderstanding. The dBd that gets 2.15 dBi gain is not the dipole that you mount in your back yard. It is a very specific theoretical antenna made out of an infinitely thin "perfect conductor", is mounted in free space, has no losses, and has nothing around it to affect its radiation in all directions, including an earth and a feed line. If you mount an actual dipole in your back yard, you will find that, unless it is very close to the earth, it has noticeably more gain than the dipole referred to in dBd. They are simply not the same thing.

    There are others out there as well, such as dBq, or dB gain over a 1/4 wavelength antenna, but these are all the same as the dBd reference, they refer to an antenna in freespace, and is made out of infinitely thin perfect conductors, so even they are theoretical in nature.

    I don't know of any reference for an antenna mounted over an earth. I'm not saying they don't exist, but I haven't seen them mentioned even in engineering level texts.

    I've actually experimented with the concept of putting an actual dipole in the same place of an antenna as a reference for comparison, but it isn't so easy. Do I mount the dipoles feed point at the same height as say a 5/8 vertical antenna's feed point, or do I put its lower tip at the height of the bottom of the vertical element, or do I put its upper tip at the height of the top of the antenna? All three of these will get you different results in comparison to the antenna in question, so which one should I use? People could very easily accuse me of manipulating the data in such a case even when the intention is the opposite simply because I didn't get the results that someone else wanted to see. Perhaps I should somehow factor in all three? I can go on here, the more I played with this the more questions I've had. Unfortunately, there really is no easy answer that will satisfy a solid baseline, such as the dBi that I mentioned above, or for that matter will please everyone.

    So, what does all this have to do with you and your antenna. Well...

    Question 1a) Is the manufacturer's gain claims possible in the real world? Yes, even the a99's outrageous sounding gain claim is actually possible (this is assuming they they are using dBi when no reference is mentioned)
    Question 1b) Will that gain happen at your mounting location? Unless you get the conditions exactly right, its not likely, and honestly likely to be less, and in some cases far less than the advertised claim.

    Question 2) Do real world antennas have different gain in different places based on where the antenna is mounted and what is around it? Yes, definitely.

    Seriously, there is a lot more to gain that most people realize. If I took everything I've ever seen said on this forum about gain and put it in perspective, that is similar to the summery on the back cover of a rather large book on the topic. A glossing over, if you will, the true nature of what gain is and how it works to make it easier to understand. The various ways of measuring gain, which measurement is relevant for what purposes, ect, ect. Gain in the real world is more than looking at a pretty chart that you or someone else produced and saying something like "I have that antenna so I have that gain to".


    The DB
     
  8. Crawdad

    Crawdad Down in the mud invasive species

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    Thanks, The DB,
    Well written and helpful.

    73
     
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  9. edfiero

    edfiero Active Member

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    I think the dbi measurement is fine so long as any gain references include this indicator. Afterall, what we are really looking for is to understand how antenna A (like a 3 or 4 element Yagi) compares to antenna B (like a V quad).

    If they are within 1 or 2 dbi of each other, in the real world you aren't likely to notice any difference in performance. If difference is 3 or greater then you might be getting to the point of saying one will outperform the other.
     
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  10. lonestarbandit

    lonestarbandit 4-2-9 Central TX

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    Glad to hear someones heard one in the wild. They seem to be pretty rare animals.
    And now that I see theoretical performance is equal to a Siro 27-4 thats 1/3 the cost I can see why they are so rare lol.
    But I done what I done now thats what I'll have to run once it arrives lol. I won't reverse course on the poor distributor a 3rd time. Probably cant anyway as VQ3 was special order item lol.
     
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  11. Slowmover

    Slowmover Elmer

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    I barely know a thing, but I’d rather have what you’re ordering.
     
  12. lonestarbandit

    lonestarbandit 4-2-9 Central TX

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    I've found this. Is it accurate? IDK. But I'll put it here for arguments sake comparing a 2 element Delta and 3 element Delta vs a 4 element Yagi.

    https://www.claw.deltaloop.it/en/delta-loop-vs-yagi/


    DELTA LOOP VS YAGI




    Ever since Loop antennas came out, the controversy that has most characterized the debate over which antenna is superior has mainly focused on the comparison between the two systems’ forward gain.
    Even though Loop antennas, as fully shown, have a significantly higher gain compared to the homologous Yagi-Uda models, there are other features that make Loop antennas interesting and preferable.
    Here are some noteworthy features.



    GAIN

    As an integration of the diagrams shown in Why Delta Loop about the comparison between Loop and Yagi systems having the same number of elements and between Loops vs. Yagis with the same boom length, what follows is a diagram regarding the comparison of two different 14 MHz antennas, published on the ARRL Antenna Book, edition 21.[​IMG]
    What has been made is the comparison of two streamlined models having the same boom length (ca. 8 metres) and different number of elements.
    Notice, in particular, the larger number of elements on the Yagi-Uda model.



    ELEVATION ANGLE vs. HEIGHT FROM THE GROUND

    A Delta Loop and a Yagi antenna, placed at the same height from the ground, show a very different take off angle (elevation of the main lobe’s signal).
    The smaller is the take off angle, the bigger is the distance of the bouncing RF signal transmitted by the antenna, the better are the chances to make QSO at higher distances.
    The following diagrams show typical take off differences between Yagi-Uda and Delta Loop systems. Note that at 6 metres from the ground is found a difference of as many as 8° in favour of the Delta Loop. By using both diagrams it is possible to better analyse the importance of the elevation angle.

    [​IMG]
    [​IMG]
    Credits: ARRL


    HORIZONTAL/VERTICAL BEAMWIDTH @ -3dB

    By comparing the typical beamwidth of a Yagi and Delta Loop system having the same forward gain, can be noticed that the -3dB beamwidth of a Delta Loop is basically wider than that of a Yagi-Uda.

    [​IMG]
    This is a precious feature both for long distance DX and for competitions (i.e. Contests).



    PRACTICAL COMPARISONS

    The summary of the features that make an antenna more performing is shown in practise: situations in which all the intrinsic (antennas’ characteristics) and extrinsic (propagation modes, morphological site characteristics, etc.) variables occur, which are typical of all installations.
    Here are some interesting studies carried out by practically testing (at the same time) compared antennas.



    Ham radio Magazine – September 1978

    Glenn William (N2GW) makes a 2 element Delta Loop 14 MHz, which he compares with a 3 element Yagi and a 2 element Quad.

    Here are his conclusions:

    Conclusion
    The 2-element delta loop has been a real performer for me. It’s allowed me to compete in several DX pileups and comparefavorably with others using full-size 3-element Yagis and 2-element quads. Even after my linear was recently sidelined, I was still able to work out very nicely just using my exciter. Also, the low vswr allowed me to bypass my antenna tuner and still enjoy a vswr of less than 1.5:1 across the entire band.


    QST – October 1966

    Robert Fitz (W4RBZ) compares the two systems installed on two 25 metre tall towers, taking notes of the received signals.

    [​IMG]

    The results represented in the chart show that in the 73% of the cases the Loop had the same or better performances then the compared Yagi.

    QST – February 1971

    John Parrot Jr. (W4GRU) compares 4 different Loop models with a 3 element Yagi.

    His conclusions:



    The antenna tests indicate that:
    1) One can expect to achieve the same or better results with a two-element quad of proper dimensions than with a three or four element triband Yagi.
    2) A wide-spaced quad will perform substantially better than a close-spaced quad.
    3) Dollar for dollar, the quad appears to be a better investment than a Yagi.


    [​IMG]

    It is intersting to observe that openings to the U.S. lasted 15 to 30 minutes longer on each end of the period than with the Yagi.
     
    #42 lonestarbandit, Jun 21, 2021
    Last edited: Jun 21, 2021
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  13. snippits75

    snippits75 Well-Known Member

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    Don't know about the VQ3, but I do have a VQuad. It is an excellent antenna.

    At 12 ft to the boom on a temporary mast, it works great for DX. It's now 18 ft to the boom, and I am very happy with it. Excellent ears too. I hear stations that other locals around me simply can't hear.
     
  14. Jay Mojave

    Jay Mojave Well-Known Member

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    When you get your V3 up check for sharp nulls off the side of the beam say 90 to 110 degrees off the front the front of the beam. Yagi beams have this sharp null some times -30 to -40 dB but with only a few degrees wide.

    Jay in the Great Mojave Desert
     
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  15. lonestarbandit

    lonestarbandit 4-2-9 Central TX

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    Thanks for that information Jay and Snippets.

    Near as I can tell VQ3 is a V Quad with added boom length and an added element. So essentially V Quad plus.
     
    #45 lonestarbandit, Jun 22, 2021
    Last edited: Jun 23, 2021

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