Modified Vector 4000

[Marconi]

Alexis, I didn't model over Real Earth, maybe I should have done that too, just to be sure.

Alexis, I made the NV4K model in Free Space into a model over Real Earth model.

As I expected, the difference between the Vector and the Vector over the 24' x 3" boom to show us very little difference in the match and maybe a small difference in maximum gain, and surprisingly, that is how it turned out.

I can't model a big yagi horizontal with a NV4K above it...because It has too many wires and takes more segments than the 500 segment limit I'm allowed with my version of Eznec 5.

The difference for the NV4K, with and without the boom added, change the matches very little, but below are the gain differences noted.

NV4K @ 36' = 4.30 dbi gain at 8* degrees - with no boom below
NV4K @ 36' = 4.01 dbi gain at 8* degrees.- with boom 48" below

I still have to see if I can model the GM with the physical choking coil below it, so I can then compare the GM with a similar boom below it.

I just got the dimensions for the wire radiator including the choke from a video I posted earlier on WWDX.com showing a fellow building a home made Gain Master and giving us his detailed dimensions.

 

[Marconi]

I still have to see if I can model the GM with the physical choking coil below it, so I can then compare the GM with a similar boom below it.

I just got the dimensions for the wire radiator including the choke from a video I posted earlier on WWDX.com showing a fellow building a home made Gain Master and giving us his detailed dimensions.

Alexis, I've been trying to construct the Gain Master with the physical choking coil at the bottom of the radiator, the stub, and capacitor that provides the matching, but I haven't figured out yet how to make the bottom portion of this coaxial radiator, including the choking coil, into a coaxial radiator like the real antenna.

Again, I wanted to see if getting this coil close to the 24' x 3" boom idea I made earlier with the NV4K, would show us the GM acting badly like other's have reported, including what I saw 1st hand with my own Gain Master.

So, maybe some good operator with a GM can try and duplicate setting his GM close to another big CB antenna on the ground below, similar to my experience, and then tell us if being close (<>10') makes any noticeable changes in the match for sure with the Gain Master.

Sorry, I just could not get this project thru my head.

Currently this only person I know that models here on WWDX.com for sure is The DB, maybe he can help or give me a clue on modeling the choking coil.

So maybe or maybe NOT, Drifter might have something more to add about his Beam and NV4K setup. We know it has a good match and it looks to be well installed in his picture.

 

[Alexis Mercado]

Thanks Marconi for your effort. I am going to use a MFJ or a T-4 Radio Works derrite line isolator Which one do you think would make a better isolating job ?

 

[Shockwave]

At 10 or 12 feet of separation between the GM and an M-104, I had good results with no changes seen in the match. Keep in mind the extremely wide bandwidth of the GM will tend to hide shifts in resonance if you are testing in the center of that bandwidth. You'll want to check the upper and lower limits and see if the 2:1 bandwidth has changed on the ends.

 

[Marconi]

At 10 or 12 feet of separation between the GM and an M-104, I had good results with no changes seen in the match. Keep in mind the extremely wide bandwidth of the GM will tend to hide shifts in resonance if you are testing in the center of that bandwidth. You'll want to check the upper and lower limits and see if the 2:1 bandwidth has changed on the ends.

Donald, I think I experienced my problem seeing the match looking bad when I first got my GainMaster. I took my Sigma4 down and put the GM in its place. I laid the S4 on the ground underneath the PU Pole and thought to remove it later.

Before I raised the GM up I checked the match and it was bad. I removed the S4, and it then checked good. I just figured the S4 had some effect on the new GM and I posted about it here. I was on an 8' ladder and my PU Pole was all the way down, so it as about 10' - 11' feet tall where the GM coax attached.

I'm not sure, but I seem to recall others reporting something similar about this new GM, back when it first came out. In fact mine may have come over with one of your orders from Sirio about that time.

Now I seem to recall you might have said the same thing back then, but I never took it down to try and check it. It stayed in the same location until lightening took the middle sections out where they connected and the wires were a little burned and solder melted at the capacitor. the feed point connectors also blew out and I didn't find those parts. Below is a PDF file of the coil.

 

[Shockwave]

I've had the S-827 style matching coil, unwind itself the same way after lightning strikes. The only omni Sirio makes that can handle lightning is the Vector and even then the stock connector and gamma match can fail. DC grounding only works well when the path can handle the current of the strike, all the way from antenna to ground.

The Vector is longer than my M-104 so 11 feet of separation is probably too little when the Vector was laying horizontal under it. Therefore it you have a boom of 30 feet or more, you may need more then 11 feet of vertical distance to prevent interaction.

 

[FredTx63]

Speaking of modified Vector 4ks... I have an upgraded "10kw" gamma for a New Sirio Vector 4000. I purchased it thinking I was going to try one out and then never went that direction. If someone could use it, I'd send it their way if they covered shipping. I still have the USPS box it came in so it'd probably be inexpensive to ship.

https://www.ebay.com/itm/10-KW-GAMM...425245?hash=item3664af035d:g:KGkAAOSw2DBasDUa

PM me if you want it.

 

[bob85]

Eddie,


From what i have read about NEC so take this as something to look into not as fact,

if you want to use coax in the model to include coax losses & matching you use the transmission-line function in eznec for the coax parts,

but the coax braid won't carry current & radiate unless you add an extra wire in parallel with the coax to simulate the coax braid,

coax is a 3 wire transmission-line,
center conductor
inside surface of braid
outside surface of braid.

 

[Marconi]

I have the dimensions for the coil. It is 16 turns. 2.598" inside diameter that I think is 0.2020" coax inside diameter. but this is the way I see it when I make the coil which I estimate is about 5" tall. I added images that indicate the dimensions for the main wires in the antenna, wires 1, 2. and 3, including the 130 wires for the coil.

Page 1, shows the Average Gain results = 1 and other details.

I setup these coil wires using the Create Tool and I ended up with 130 wires that are about 1" inches long per the wires at the bottom of page #4, the image of the coil.

Next is to make this 130 wires coil into a transmission line using the TL tool. I will have to somehow make a 130 short transmission lines all connected in series. I doubt I can manage the complications of this task, but if I could...I have no idea how it would work.

Then I will have to figure out how to do the stub and the capacitor to get a match, even though matching is not necessary for some reliable results...according to the Average Gain = 1.

I sent all the details I have done so far, including the gain and angle in Free Space, the match, and the wires descriptions of all 133, wires for the model. Again this is 130 wires for the coil and 3 wires for the rest of the antenna = 133 Wires and 221 segments noted on page #1.

Bob, I'm too old for this and I already have trouble seeing Eznec.

But, I sure wish we could test this antenna over a beam to see what happens, but checking it, as is, is not likely to give us this info.

 

[bob85]

Eddie
I am sorry I can't help with the gain-masters coax and choke other than modeling coax with the Tl function treats coax as a two wire none radiating line,

you need to add a parallel wire to simulate the braid if you want it to carry any current & radiate which you do its a coax dipole

how you could make that work in the choke area even with good eyes & youth seems like a nightmare to me,

I think the problem with putting the choke & voltage node so close to the beam could be distributed capacitance to ground detuning the choke,

if that's right just using a parallel wire from the feed-point down ending just above the choke won't show the detuning correctly,

I don't see any evidence that sirio included the choke from what they show us in the images of GM vs conventional 5/8,

current distribution looks perfectly symmetrical just like a 5/8 wire dipole with the source at its center & that's almost certainly not true like all other mickeymouse claims they make about the antenna,

personally I would not put a gain--master very close to a beam or earth.

 

[Marconi]

you need to add a parallel wire to simulate the braid if you want it to carry any current & radiate which you do its a coax dipole

Bob, I understand a little about the idea using the Feed Line tool. It's adding each of the little geometry details to the FL feature that I see as the problem in this case.

The process of adding the little parallel wires happens when I use the 2 port Transmission Line feature. In the model above, I had not attempted to use the Feed Line feature yet. I just added the coil at the base of the GM and there it simply added inductance to the antenna.

Then after the FL feature is completed I'd probably get a few geometry error warnings, I'd have to try and fix, and then I would still have no confidence the whole process will work as intended.

I recall comments being made in the past, from other's, saying things like, "...don't let your choke physically touch the mast...," etc.

So, I think you're right when you say:

personally I would not put a gain--master very close to a beam or earth.

But, Shockwave tells use in his personal experience he saw no ill-effects. I was hoping someone would test this idea, but I forgot Shockwave already told us back in the days when I reported this problem...saying:

At 10 or 12 feet of separation between the GM and an M-104, I had good results with no changes seen in the match. Keep in mind the extremely wide bandwidth of the GM will tend to hide shifts in resonance if you are testing in the center of that bandwidth. You'll want to check the upper and lower limits and see if the 2:1 bandwidth has changed on the ends.

The manual does mention concerns for both 10' feet and 18' feet above metal objects however.

 

[bob85]

Eddie,
I was thinking a foot or two like some people mount end-feds above a beam,
Sirio say 3mtrs minimum from roof so that's probably ok like shockwave said.

 

[Marconi]

Here is an example of modeling 1 coaxial Transmission Line to the multi wire coil. I already see I need to make these wires with 3 segments each, instead of only 1, in order to bring the connections closer to the wire ends...instead of in the middle of the wires, as noted here.

Hope you can see this "T" in a little box, with a dashed line between wires #4 and #5. This is the indicator for the other parallel wire everybody is looking for with this 2 wire part of the injection object in modeling with Eznec.

 

[Marconi]

Eddie,
I was thinking a foot or two like some people mount end-feds above a beam,
Sirio say 3mtrs minimum from roof so that's probably ok like shockwave said.

I agree, the Vector and an EFHW would probably be OK like you say, but I saw the problem at about 11' feet as best I recall. I know I had the GM on top of my fully collapsed PushPole with an 8' foot metal ladder, when I checked the GM match for the second time. I also checked the match with the GM laying on three sawhorses about 3' feet above the ground and the match was fine.

That said, I just realized the metal ladder was even closer, but all I did after that was to remove the Sigma4 and on rechecking the match...I was good to go and the ladder was still right there under the GM waiting to be pushed up. Maybe all of the mass from the ladder and the S4 was the killer, and removing the S4 did the trick.

I just raised it up, it worked fine, and I never looked back or checked to try and determine with really might of happened...I had a new antenna and I wanted to see how it worked.

 

[Marconi]

Bob, maybe I can use less wires, making each wire longer, so I can use 3 segments on each 3" wire, forget the circular look of the coil.

I used 8 segments per turn so the coil would look more like a circle. Never know what folks might think if a model does not look like an antenna in the magazines or in their back yard.

I think maybe the model below will fix the problems, and help make the TL truly parallel with each wire and a "T" in the box for each wire in the coil. Can't see the dashed lines that represent the 2nd parallel wire using this tool anymore, but they are there none the less.