Modified Vector 4000

[HomerBB]

There is always a future in things when folks are willing to roll their own. Change doesn't necessarily mean the end of a thing. It can herald a new approach.
I once said I wouldn't buy online, but now I go there first.

 

[HomerBB]

I got started on my 6m V4k. Good start with more components to fabricate. Tried a Yagi gamma on it, but may build my own. Dog bone is too long, so another is in the plan.
Used Shockwave's formula of 9212/freq. 1/4^ radials and ring circumference. Another place I noticed a suggested ring circumference of 1/4^ minus 9%... Going with the first for now.
I'll polish it up before I permanently fly it.

 

[HomerBB]

I had obligations to tend to today so not much done on the 6mV4k.
I did, however, manage to shorten the gamma dog bone and build another gamma match.
I know things will likely change when it goes higher up into the air, but on a PVC pipe 6.5' above the ground I have resonance (thank you, Shockwave) across 2m and without fine tuning 1.6:1 on 144 Mhz and 1.4:1 on 148 Mhz. It was lower down to 1.1:1 around 146.5.
I'm pleased with my progress so far. Like most of the antennas I build this shows my trademark quick and dirty look. No one will be lining up for anything. . .

 

[HomerBB]

I had a little time today so I got it up 16' to the feed point. As I expected the SWR readings went south.
It isn't at its permanent location, yet. Not done, not enough time today, and too windy.
A little fiddling with it and here is what the analyzer says so far.


If I can get that sharp rise toward 54 MHz down a little more I'd like it better, although, it's quite usable in the usual places I frequent. . .

 

[Robalo]

. Thi is my antenna at 11m

 

[HomerBB]

Latest photo:

 

[Drifter]

Here is my New Sirio Vector 4000.

 

[Alexis Mercado]

Here is my New Sirio Vector 4000.View attachment 36905

How is is working above the yagi ? Vector 4000 instructions says that it don’t like nearby antennas.

 

[Drifter]

It’s working great. Tuned flat Across C B band.

 

[davev8]

Ok i am guessing there must have been a response to the pdf at CB antennas.com but its probably 5 years back in this thread and take 2 days to find so what was the thoughts on this article

http://cb-antennas.com/wp-content/u...ik2Ci-gjfSg0g7yjjeu5ppS24ZAk5SdvaqQutaMaHtjKk

 

[davev8]

oh of interest i made a vid beefing up my V4K after the weeks of storms we had in the uk topping 70+ mph winds we had ..i was very pleased how the main radiator stand up to it ..it did help being on a flexi mast ..it was going over at 90 degrees..an Imax 2000 on the same coast did snap its middle section ,,,i don't know how it was mounted the vid

 

[Alexis Mercado]

Here is my New Sirio Vector 4000.View attachment 36905

Hi drifter. Did you isolate your Vector from he mast ?

Do you have a picture of how it is mounted on the mast ?

 

[Marconi]

How is is working above the yagi ? Vector 4000 instructions says that it don’t like nearby antennas.

Alexis I think you might be right, that the NV4K instructions give a caution about other antennas close by. IMO that is likely a good idea with all vertical antennas installations.

However, the beam that Drifter shows us above is Horizontal, and it looks to be maybe 4' below the Vector. I was not sure how that might work in this case, so I modeled the NV4K over 24' x 3" boom to see if the model showed some ill-effects being so close.

My model of the NV4K shows no sign of ill-effects with the boom only 4' below the bottom of the antenna as we see in the models. I also recall some discussion or a report by someone saying the NV4k, with its swept-up radials, is less effected by things around it.

I do see some likely problems with the Sirio Gain Master however, and the GM manual talks about this issue.

I will attempt to model a Gain Master with the idea to compare it to a GM over a similar boom. In my experience with the GM I reported an incident where I saw the GM match skew noticeably with my Sigma4 on the ground directly below, about 12' below. Sirio does caution for the GM to mount it as noted here.

"Be sure that the antenna is installed at least 3 meters above the roof of the nearest building and 5-6 meters above or away from any metal in the area."

I think the difference here is the choking coil that is at the bottom of the GM, and how important its effects are on terminating the physical bottom end of this Center Fed 5/8 wave antenna, where balance is essential to operations.

 

[Alexis Mercado]

Thanks for your input Marconi. I was thinking about installing a line isolator right at the coax connector, just in case.

For me, Drifter’s Vector 4000 is just above the yagi ( see picture ), I think is no more than 1-2 feet above it.

Mine is going to be 4-5 feet above a Mosley TA-33 WARC yagi.

 

[Marconi]

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

So, you could be right, either or both his beam and his Vector could be working at less than maximum performance without him even noticing for sure...if the difference is small. The problem with any antenna showing Common Mode Currents...is the ill-effects on the pattern. And aside from modeling, I think the radiated pattern is really hard to determine without some expensive equipment.

Drifter didn't tell us much about his installation, so maybe he can tell us more about what he did to guard against CMC, if he did anything.

Maybe Drifter worked his beam enough by itself and the Vector too in order to give us some ideas how they both worked before and after mounting them together. It seems to me, that would be the only way he could really know for sure. Like you say Alexis, CMC issues could be a problem, and a line isolator set in the right position...makes good sense.

I still think the GM was the antenna that might not work so well above a beam as in this case. That terminating coil (choke) is likely very sensitive the metal close by...just like the warning in the manual, might be suggesting.

That coil at the bottom of the GM seems to me to be doing a big job at stopping the currents on the radiator at the right spot at the bottom of the 5/8 wave element, and still maintaining the balance we would expect with a center fed 5/8 wave dipole supported by a vertical mast beneath.