Base New Vector 4K radiator at 0.75 - 0.82 - 0.875 wavelength.

[Marconi]

LW 150 instructions I got with the antenna I took down.

Homer, sorry the hand drawn image did not turn out well and it has some specific dimensions noted. I will see if I can figure it all out and, if so, maybe I'll model this antenna and give you his specific dimensions per section from the base to the tip.

 

[Marconi]

Homer, sorry but the images have too much missing to make a model. I do see the overall length is 29' 9" with 18" mount below the radial hub. He shows the radial hoop is 96" inches the the radials are 84" inches.

He shows the gamma overall is 48" inches and the base it 18" inches. He also shows the top of the dog bone is 26" inches above the base at the feed point on the top of the radial bracket. He also shows at 4' feet above the base the radials are 8.5" out from the radiator. Not sure if that is center to center however. He shows the tip is tune-able and is set at 47.2" inches exposed.

I wonder if the guys at Sirio came from this CTE International? A lot of the CTE construction ideas look very similar to Sirio today.

 

[bob85]

Eddie,
the cte was around years ago, before the vector was available here,
they look like the same antenna, other cte antennas look almost identical to sirio antennas, probably made by the same people.

 

[Marconi]

Homer, here is a pictures of radiator tip showing what this old guy did to to replace the part above that he said he lost in a wind storm some years earlier. He also said it never did work right after that. It was #3 copper wire and it was longer, but I cut it off because it was bent like a pretzel.

 

[Marconi]

Eddie,
the cte was around years ago, before the vector was available here,
they look like the same antenna, other cte antennas look almost identical to sirio antennas, probably made by the same people.

I thought that is what I was suggesting Bob, but I don't know the history...it was just a wild guess based on what I saw that was similar.

 

[Marconi]

I had trouble matching until I built a gamma with a tube somewhere around 17" long x 3/4" diameter with a rod 30" long. It was dicey finding a working relationship between the rod extension amount and the strap from the vertical to the rod location. Once found it did a great job over a significant bandwidth.

Homer, I read in your link on the "Vector 4000 Remake" saying you did not know the dimensions for the gamma match. You were probably asking the wrong guys...I had this info back then.

I'm can't be sure about those dimensions working, because the info was from somebody else. I did know a little about the LW150 antenna from a neighborhood CB buddy that had two old Sigma styled antennas back in the day, long before I ever heard about Siro. I never owned a Vector however, but I did buy 3 Vector knockoffs for other guys on the radio and I've posted that story on WWDX before.

I tried a 7/8^ length, but believe I backed it down to 3/4^ (27'6") for my best results.

I don't recall you trying a 7/8 wave radiator. I just recall your antenna might have been longer than the stock Sigma4/NV4K. Until now...I never knew for sure. Same goes for Booty Monster.

I tried the same thing making my A.S. Sigma4 about 2' feet longer and I could not get a match anywhere within the full range of the stock gamma match...which wasn't much.

My gamma dimensions:
Base is 1/2" x 10" inches
Rod overall is 38" x 3/16" inches
Rod to dog bone exposed is 22" inches above top off base tube
Dog bone from feedpoint is 32" inches

I could make no tuning progress with the radials attached against the vertical with no standoff.

I seem to remember us talking about that too. I've said before, this offset may also be necessary in such a real world antenna. However, I think I read in your V4 Remake thread, that your first or second V4K/G4 antenna with this design that worked really well...had the radials connected directly to the mast, (I could be wrong though).

 

[bob85]

Eddie,
when you extended the sigma by 2 feet did you move the gamma strap for lowest vswr before you adjusted the gamma rod ?

 

[Marconi]

All I can remember is seeing the match was really bad after I added 12" inches, so I added 12" inches more.

I can't recall much of what I did next, but I figure I tried moving the dog bone up then down a 1/4" inch at a time. I do remember having the thought (maybe in vain) that the match point would probably raise up higher on the radiator.

I have several pages of the iterations I did in one of my antenna note books, but I would have to check several composition notebooks full of notes. I have tabs on some of my important projects I did that were informative, but I consider this was not working as I hoped.

I also recall trying this with the S4 mount on a 9' x 1" copper coated steel ground rod that I had buried into the ground about 4' feet. I used this to attach my antennas to ground in my back yard away from the house at about 40' feet away.

This was the same place I originally tuned my Sigma4, and the match did not change much on raising there or at my other antenna mount a couple of feet away...outside the window of my station.

Bob, do you remember how this went with you? What kind of gamma did you use? Did you have to make a lot of adjustments to tune it back in?

As usual, I wish I could do it all over again.

 

[bob85]

we swapped sigma & vector 7/8 radiators, the antennas used the gamma that came with the basket, we did have to move the gamma strap & gamma rod to retune

 

[Marconi]

Well Bob, I tweaked the 370" model to get the Average Gain results to equal a perfect = 1.

I also fixed the skewed pattern in the 022718 model and made a note "Fixed" on the image. It is included in the PDF file for the Real Earth model. This balanced the load on the radiator and the skewing went away.

I also fixed the very small diameter radiator created by the skewing. Now the average diameter is set at 3/4" overall for the entire radiator length. I plan to do this model using taper just to see what really happens using my Eznec5...which is said to be unable of handling taper and maintain accuracy. If that works that should eliminate my making averaging errors in figuring what the element diameters are.

1. are the updated overlays
2. is the model in Free Space with the Eznec Control Center screen showing the Average Gain.
3. is the model over Real Earth and this time the 370" model shows the best gain.
4. is a model I did on 01/16/15 as noted in the image of my Eznec index file for models. Underline and the 1st model in the list. Was not ISO, match was bad, had CMC on the mast, but the average gain acceptable and well within a good range of value considered accurate.

Back then Bob, I repeat I wasn't even Isolating the mast back then unless asked. You can see CMC on the mast and the 1/2 wave portion of the mast in the middle is out of phase with the radiator.

IMO the CMC manifested here is destructive to gain. That said the model still showed gain of 4.11 dbi, the match was bad, but the Free Space model showed only 1.006 Average Gain. That is not prefect, but it is still pretty good. I don't think we will see any CMC currents or the effects...the way I do the models today getting the AGT to = 1.

Bob, for a long time I was expecting a greater difference in the gain based on your early claims, but I have to agree with Henry...according to my models and his report...there just doesen't seem to be that much difference...as long as the current maximums are set at a similar height or the antennas or similar in height when set at the same feed point height.

But you are right the taller antenna does show the most gain, but not by much.

I recall Donald telling us he used field strength readings...and I have to wonder about that. I'm not saying the idea is not viable...but I do wonder how effective that is, how is it done, and to be sure of the readings. Especially back in the days when local CB traffic in big cities was a mess and being on-air was very very busy.

How say you?

 

[bob85]

Donald explained how he did it on vhf broadcast band & what receiver he used,
i was doing it the same way in the early 80's using uniden cb's & hf sets,

i don't have any problem using reliable locals for testing,
obviously you don't want to be messing about when skip is running or there are locals on other frequencies pumping your receivers agc,

keep an eye open for planes flying over causing multipath summing & fading,

You could argue that the clutter around my antennas effected the results & i would agree with that, its the only explanation i can think of,
you have seen how buildings even wooden buildings can attenuate signals,
its more open here but i still have clutter, im not in a desert with nothing around me for miles
things you cannot include in a model can effect the result more than any minor difference in antennas,

The beauty of FM is its normally stable & you can hear multipath & agc pumping,
using AM or SSB is like trying to weigh a trampoline while a fat bloke is bouncing on it.

 

[Marconi]

Donald explained how he did it on vhf broadcast band & what receiver he used,

I have heard discussions about using an attenuater, but I'm not sure Donald talked on the idea. I could be wrong and it was someone else however. All I seem to recall is his using field strength test. Some how, even back then, Donald was reporting his idea for making more gain with the Vector style radiator set at 0.82 wavelength. He and I both were not able to model the idea with any success, and he blamed the fact on Eznec software limitations.

i don't have any problem using reliable locals for testing,

FM mode for CB is against the rules here in the US. There are Pirate FM stations around our the US, but they are typically above 80 meters to 100 meters. I think that is illegal too. Thus FM never seemed popular in my experience. That said however, I do agree with your words on the subject.

you have seen how buildings even wooden buildings can attenuate signals,

Correct...I have seen such attenuation effects and even though IMO this can be devastating for results...I think a lot of folks that set their antennas very low...may not even realize the effects...that is unless they take the chance to raise it up a few feet more and get the full antenna above their own roof top.

 

[Marconi]

I'm working on the 7/8 wave model using taper.

I said earlier...that I thought maybe making my AS Sigma4 about 2-3 feet longer might require the Gamma dog bone to go up. but thus far I see the feed point wanting to be much closer to the radial hub...sorta' like we see on the Vortex model they post on their Website.

Bob, do you have any recollections for how your gamma match ended up...when making your radiator longer and using the Avanti Sigma4 gamma?

Homer, do you recall anything? Did you try making the gamma closer or further away for the radial hub...when you tried the longer radiator idea?

BTW,
My Sigma4 gamma is outside and centered between two radials by about 3" inches. So Homer, my gamma is not in the same plane as the radials.

I also found out from experience that the gamma really needs to be well centered between two radials...or else the match will be ill-effected.

Thanks,

 

[Marconi]

Bob, here is the model using taper on the radiator elements. I used the same matching device I did earlier on the 7/8 wavelength model at 380" inches, but due to the taper I cannot display the radiator as one wire that shows the full length for the radiator wire.

So, I selected the radial wire #12 and the ISO mast wire #60 to show the wire lengths for the Free Space model and the Real Earth model.

It is more difficult to make these antenna using taper, but this does not show me that Eznec5 fails to show good results using taper.

 

[bob85]

Eddie,
i don't think eznec limitations stop it handling the vector, it uses MOM the same as cst uses in the model Donald posted,
i think precautions must be taken to get accurate results,

eznecs graphics are crude compared to cst but not nearly as open to our own interpretation like cst fancy graphics are,

sorry i don't have any measurements for my old antennas, i don't have measurements for my current antennas apart from the astroplane,
back when i was experimenting i never thought one day many of us will have something they will call the internet & i will be needing measurements to share with other people around the world

4.69dBi that's higher than sirio's 4.15dBi whats going on there Eddie?