1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice
Dismiss Notice
This forum does not allow a single user to have more than one username. If anyone wants to change their username contact an admin and it will be done. Multiple accounts belonging to the same member will be deleted without warning.

Modified Vector 4000

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

  1. Marconi

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

    Joined:
    Oct 23, 2005
    Messages:
    6,998
    Likes Received:
    1,964
    I could have turned the segment connections off, but I figured you were probably the only one that would notice, and maybe understand what I did and said to sound like an ?????.

    Am I wrong?

    If you use the Way Back Machine you can check-out the Vortex video. If you get to the models, for the M2 and M2 and you check the number of wires and segments on the Eznec Control Center images, and then just get an idea for the number of blue dots. These are the wire ends. I think you will see the loop has more wires than the 28 indicated on the Control Center details.
    total wires 37-9 = 28 wire for the loop.



    radiator, hub, and radials use 9 wires and the rest is for the Loop.

    This leaves 28 wires for the radial loop. I estimate there might be 40 wires in the loop image we see.

    IMO, it is a stretch to consider there are only 28 wires in the loop.

    The M1 shows 39 wires and 9 for the radials, hub, and radiator...this leaves 30 wires for the loop. The use of both 28 or 30 wires, in this case. will leave some wires in the loop at different lengths, and thus the current distribution could cause and unseen problem. How much, I'm not real sure, but maybe about as much as failing to getting the segment lengths = between the radials and the radiator in the Sigma4 design.

    This little differences can make a difference.

    This is something to consider that nobody is talking about. This is why I harp on the use of the Average Gain results in Free Space models. A topic that most claim is not a real model...claiming they are imaginary and are worthless.That is until they want to try and prove a point about steering the angle for the Sigma4. This is an issue that only develops in some Free Space models and it all came to light in those discussions here on WWDX.

    I will stand by your findings. Are you going to test at 5-6 miles again?

    I have a story about comparing antennas to a buddies signal that are close-by, maybe 10 miles, and I've posted the story before.

    Have you ever tested a longer distances?
     
    #766 Marconi, Jan 10, 2021
    Last edited: Jan 10, 2021

  2. Shockwave

    Shockwave Sr. Member

    Joined:
    Sep 19, 2009
    Messages:
    3,639
    Likes Received:
    2,845
    The length of the main radiator in the Vortex using a 3/8 wave cone, has not been extended. In fact Bob says it's been made a little shorter than the .82 wavelength. Therefore the phase angle along the length of the main radiator has not changed and the phase crossover point has not moved up to match the location of the ring. Changing the length of the basket does not change the phase angel on the main radiator. Only lengthening the main radiator to 7/8 wave would allow proper phase alignment with a 3/8 wavelength cone.

    Previous testing showed that gain starts to drop again once you approach the 7/8 wavelength radiator. Although, I'm not aware of the 7/8 wave being tested with a 3/8 wave basket. In any event, the Vortex is no where near 7/8 wavelength. I've also been wrong before so, I'll wait until more results are in to pass final judgment. If they show something good, then I'll try and wrap my brain around how that is possible with the phase angles and higher CMC impedance.
     
  3. The DB

    The DB Sr. Member

    Joined:
    Aug 14, 2011
    Messages:
    1,893
    Likes Received:
    1,243
    Not necessarily. It is best practices to get all of the segments to be the same size, but in many cases, one of them being specifically a radial hub, and cases where you have limited numbers of segments to work with, that may not be possible. That being said, there are very specific instances where said segments have to line up perfectly.

    Actually, one way to correct an AGT issue that Marconi referred to is to adjust the length of some of the segments. As long as none of the segments on the model get to be longer than a certain % of a wavelength, then there is no need to worry, as long as the AGT checks out.

    I once thought that free space models were not relevant, but that was years ago. As with most of my views on antennas and how they work, my views have changed drastically over the years, and in some ways said views are still changing, perhaps evolving would be a better word here? Today I would tell you that you can learn more about how an antenna actually works and where it is actually trying to put its RF from a free space model than what we can see with a model over an earth.

    I do tend to stay away from posting said models because there are a lot of people that, similar to what you said will try and tell you that freespace "does not exist in the real world" and such it is useless. This tells me all I need to know about what said person knows about antenna modeling. This is one of those beliefs that some people will believe to the core even with irrefutable proof to the contrary, so its better to let them believe what they want. I find it especially funny when this comes from someone who has no actual experience modeling... What can you do? There are a lot of things in this hobby that even very knowledgeable people believe in fervently even though they haven't ever seen any evidence, much less proof... At least you, Bob, and some others actually try to get to the bottom of things.


    The DB
     
  4. Marconi

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

    Joined:
    Oct 23, 2005
    Messages:
    6,998
    Likes Received:
    1,964
    Donald, this isn't the real test, but here is a model of the 7/8 wavelength Vortex idea with 162"> radials that gives us an idea for how they might be working.

    1. is the Free Space model of the 7/8 wave version of the Vortex Q82M2.

    2. is the Real Earth model.

    3. is my best NV4K model for comparisons.
     

    Attached Files:

    #769 Marconi, Jan 11, 2021
    Last edited: Jan 11, 2021
  5. bob85

    bob85 Supporting Member

    Joined:
    Mar 30, 2005
    Messages:
    3,460
    Likes Received:
    1,349
    I noticed you probably deliberately made the segment lengths different & junctions not level to make the 3/8 look better than your original model Eddie,

    Nav is only 4.5 miles as the crow flies from me, nobody else i know local is setup for 6mtrs vertical & nav has a dBm meter so we can test both ways,

    testing over longer distance is out while in lockdown.
     
  6. Marconi

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

    Joined:
    Oct 23, 2005
    Messages:
    6,998
    Likes Received:
    1,964
    No, as a matter of fact that deal was a mistake, as I was in group mode, where I can make a change to one wire and other similar wires in a group will change too automatically. This group was a 4 wire group for the radials that were near the top of the data entry screen. Then I scrolled down to the bottom to add a mast to the model. The software wouldn't let me make an edit to other wires...while the group was active. I knew what the problem was, but with my bad eyes and shaking hands...i managed to make a change to the group in the process of closing the feature.

    When I scanned the model a big improvement in gain popped up. I realized I had just figured out an easy way for an unscrupulous operator to overstate the gain for his model.

    Sometimes these models get tricky and it is hard for me to keep up with all the changes and then remember to keep the segments etc., in good order.

    My God, savior, and creator blesses me, to still be able to deal with this complicated software.
     
  7. HomerBB

    HomerBB Sr. Member

    Joined:
    Jan 4, 2009
    Messages:
    3,674
    Likes Received:
    1,898
    I looked at the last model of the vortex. Clearly I don't know what I'm looking at because it appears the cone length is more than 1/2 that of the entire antenna length.
    Antenna = 316"
    Cone = 162.76"

    316/162.7=1.94, about 51% of total length...
    Lost, maybe..?
     
  8. nav2010

    nav2010 Active Member

    Joined:
    Sep 5, 2010
    Messages:
    189
    Likes Received:
    30
    I'm not saying the crossover point has moved from half wave downward from the tip. On a 3/4 wave antenna it will always have the crossover point at half wave. If you have a half wave monopole above the basket and a quarter wave basket then the crossover point is level with the basket. What I'm saying is - if you extend the basket upward another 1/8th wave by definition you have reduced the monopole exposed upper element length to 3/8ths wave. The question then arises where is the half wave phase cross over? Is it still on the monopole below the extended basket hoop or does the half wave use 3/8ths of the monopole in phase with an 1/8th wave from the top of the basket?
    To answer this you have to imagine the modified vector as a closed sleeve antenna rather than on open sleeve. So imagine the whole of the basket is a sheet of aluminum shaped like an icecream cone with a thickness of 2mm just like a Sirio CX J-pole but instead of a cylinder surrounding the monopole, you have a cone.
    During TX of said modified vector with a 3/8ths cone and a 3/8ths exposed monopole the current and voltage distribution is a vector sum of both 3/8th lengths and because there is a dead short between the two 3/8ths radiators at the feed point then the vector sum is 3/8ths of the upper exposed element in phase with an 1/8th wave of the top of the basket. The half wave crossover point is a vector sum of both 3/8th radiators which is 1/8 the way down the top of the cone.
    If the cone was insulated from the monopole this would not take place. Instead, the monopole would form an half wave which would be partly obscured by the cone - in other words you'd have a folded dipole where one element is blocking the other. Because it's not insulated and it's a dead short and always 3/4 wavelengths long then both elements form a vector sum of an half wave over a quarter wave no matter where the monopole and basket are in relationship to one another.
     
    #773 nav2010, Jan 11, 2021
    Last edited: Jan 11, 2021
  9. nav2010

    nav2010 Active Member

    Joined:
    Sep 5, 2010
    Messages:
    189
    Likes Received:
    30
    hw.jpg
     
  10. nav2010

    nav2010 Active Member

    Joined:
    Sep 5, 2010
    Messages:
    189
    Likes Received:
    30
    Now imagine if we took this to an extreme as per pictured below. The vector sum half wave cross over would still be in the same location because of the dead short between the cone and the monopole at the base.
    Now you'd end up with massive cone and a short exposed stub and the cone angle would fire most of the radiation into the ground.
    The vector works because it uses a vector sum of both radiators and angles of radiators to hit a sweet spot on the horizon.
    Of course the question arises of what happens to the monopole between the feed point and the top of the basket?
    It becomes redundant in one sense but not in another. It becomes a redundant part of the radiator but still forms part of a transmission line. This antenna has transmission line currents and antenna currents flowing on it simultaneously.
    hw2.jpg
     
    #775 nav2010, Jan 11, 2021
    Last edited: Jan 11, 2021
  11. nav2010

    nav2010 Active Member

    Joined:
    Sep 5, 2010
    Messages:
    189
    Likes Received:
    30
    Try using Eznec to work out the reactance of the antenna when you have transmission line currents in parallel and in series with antenna currents simultaneously. Good luck.
    hw3.jpg
     
    #776 nav2010, Jan 11, 2021
    Last edited: Jan 11, 2021
  12. bob85

    bob85 Supporting Member

    Joined:
    Mar 30, 2005
    Messages:
    3,460
    Likes Received:
    1,349
    Homer the on the mk2 Vortex the cone is within a inch or two half the length of the antenna,

    I'm not speculating on what's happening until I do a test isolated from the mast with some kind of choke on the coax in a short period of time with two antennas I'm happy have no bad connections anywhere,

    a half assed wipe over with a Scotch-Bright pad won't do,

    vectors will tune to a low vswr with parts of the antenna missing or not making good electrical connection,

    losing a full section of monopole on an old vector is no problem just tweak the gamma & your good to go, even better than before,

    snap a radial from the hub no problem,

    change the cone from shorter than 1/4wave to 3/8wave no problem,

    like Eddie said don't worry about the match the gamma sorts it out,

    so its important when cleaning up scruffy old vectors to make sure EVERYTHING is bright & clean inside & outside and making good contact,

    the sintered hubs weather to a none conductive surface & fur up where they contact the monopole & need wire wheeling & brushing back to shiny conductive silver,

    shot blasting sirio hubs leaves a dark grey none conductive surface,

    a good mod is replace the short rusting radial bolts with longer stainless studs & nuts that screw through the hub & grip the monopole bypassing the hub for a much more reliable connection for the radials and so239,

    so239's fur up with white crud & need stripping & cleaning on wire wheel & inside pin socket cleaning,

    i can't just throw a scruffy old vector together & cut the hoop down & call it done, its not the way i do things.
     
    HomerBB and Marconi like this.
  13. Marconi

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

    Joined:
    Oct 23, 2005
    Messages:
    6,998
    Likes Received:
    1,964
    Homer, models and the dimensions can get confusing at times. Your not lost, but I can only guess that the last model you looked at was this model. Modified Vector 4000.

    That model was an end fed model and it is supposed to be a stock version of the Vortex Q82 Mark 2 just as they advertised.

    My last model posted was this model. Modified Vector 4000

    This model is a gamma fed model and it is a 7/8 wave version that someone brought up in this conversation.

    Try the math on these 2 different models.

    Here are some specs off the Vortex original Website that is gone now.
     

    Attached Files:

    #778 Marconi, Jan 11, 2021
    Last edited: Jan 11, 2021
  14. Marconi

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

    Joined:
    Oct 23, 2005
    Messages:
    6,998
    Likes Received:
    1,964
    Bob and Homer, the difference in the lengths of the cone you see in the specs and my models, I explain as "geometry creap."

    I started with the given specs several years ago. Over time making a few changes to the cone length or the loop diameter, which are geometrically produced parts of the model...the radial lengths changed a little. I just never fixed the change.

    Thank you Bob for doing the refurbish-job well.
     
    #779 Marconi, Jan 11, 2021
    Last edited: Jan 11, 2021
  15. Marconi

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

    Joined:
    Oct 23, 2005
    Messages:
    6,998
    Likes Received:
    1,964
    We talked about Henry using the dbm idea for measuring signals at a distance and at some specified height in his Sigma4 report.

    He showed us what he got using dbm in modeling. That was in January of 2015 and the discussions that followed, until today, don't seem to me to be jiving as explained by those that know and use this technology.

    Bob, sometime back you told me you wanted to take your I-10K down and put up you new Old AstroPlane.

    Did you dbm test the I-10K or the A/P?

    More recently you took the A/P down and put up your Gain Master and I posted, "...I was surprised to hear about you putting up your Gain Master," right?

    Did you dbm test the Astro Plane? How about the Gain Master?

    Off hand, I don't remember you posting much about any of these antennas, at the time or since and nothing, until recently, about testing and using the dbm idea.

    I did find this however.

    I understand your weather is bad at this time and it will be a while before you get to test your 6 meter Vector and that is not the point of my questions here.

    So maybe, while we wait for better weather...you and DB could show and tell us a bit more about your testing any one of these antennas...and how they compared.

    Another question I have. I remember posting my I-10K model, showing the unique pattern it makes when adding the trombone matcher to the standard 5/8 wavelength model. It shows very good gain for both vertical and horizontal, and all I heard, for the most part, is crickets. Bob, I seem to recall something you reported about your I-10 relating to DX vs. local, but I can't find anything using "Search," and I don't remember if or what you might have said.

    So, I'll try again. Below are several overlays that might help demonstrate what I see when comparing my I-10K, Imax, and NV4K models. Before a couple of the more recent WWDX updates, I use to talk about how good the I-10K worked, for sure, when I was working WWDX contests using my I-10K back in the days. So, I don't find a thing about my I-10K back in the early days.

    That said, I figured I could have been overly influenced to see the best...simply because it was a new antenna at the time and being a typical CB'r with a new antenna...I could have it all wrong too.

    How say you.
     

    Attached Files:


Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!