Modified Vector 4000

[MrSuburban]

Homer, as you know we don't have much wind here typically, so I used twenty ounce soda bottles filled with water to hold my vertical lines down straight. They will drift around easily in any wind if not secured a little, and the match will be affected.

Such antennas are noted to be DX sensitive when setup correctly, and to attenuated local traffic and local vertical signals in particular. When I had mine installed a few years ago, there was no DX at the time and I was not able to copy local signals very well. I also think the poorer the soil conditions are in your area, the better this antenna may work.

Cecil address's what you saw locally from the Half square here.



Half Square antenna


--------------------------------------------------------------------------------
> W8JI wrote: It is true that if a dipole is low enough a half-square can beat it at very low angles, but the dipole would have to be pretty low or the earth very good conductivity. <


True, low to the earth is the main feature of the 40m half-square. Its vertical elements are ~33 feet long and the lower ends (current nodes) need to be only a few feet off the ground. Using 40 foot high supports on 40m, the half-square has 1.61 dBi of gain at an elevation angle of 10 degrees (better for DX). At 10 degrees, the dipole's gain is 4+ dB down at -2.65 dBi. But of course, the dipole beats the socks off the half-square at an elevation angle of 50 degrees, much superior for closer contacts. (40 feet is probably close to the mean height of 40m dipoles.)
--
73, Cecil, w5dxp.com

 

[HomerBB]

Thanks for the ideas on the vertical sections. We do have wind here. We average 14MPH annually, but just last week I watched my yagi on the wooden tower battered by 60+ MPH winds. That tower can dance. I wish I had those moves.

 

[MrSuburban]

Thanks for the ideas on the vertical sections. We do have wind here. We average 14MPH annually, but just last week I watched my yagi on the wooden tower battered by 60+ MPH winds. That tower can dance. I wish I had those moves.

I like Marconi's idea of the 20 oz bottles, but especially if you mount ithe antenna higher off the ground.... you need to put saltwater in there and you should pick up a few extra dbd's

 

[HomerBB]

Okay.

 

[BOOTY MONSTER]

.... you need to put saltwater in there and you should pick up a few extra dbd's

good one

 

[gamegetter]

Homer, as you know we don't have much wind here typically, so I used twenty ounce soda bottles filled with water to hold my vertical lines down straight. They will drift around easily in any wind if not secured a little, and the match will be affected.

Such antennas are noted to be DX sensitive when setup correctly, and to attenuated local traffic and local vertical signals in particular. When I had mine installed a few years ago, there was no DX at the time and I was not able to copy local signals very well. I also think the poorer the soil conditions are in your area, the better this antenna may work.

greetings:

I don't believe that soil conditions would come into play with this antenna being fed as a dipole...(a dipole has it's ground). However soil conditions would definitely come into play on the vertical which has a missing dipole and needs good ground to replace it, hence soil conditions would affect that set up. This is not to say that a dipole and your radio equipment should not be proteceted from lightning.

 

[BOOTY MONSTER]

what do you mean by "double your antenna" ? if you mean double the distance you can talk it takes a whole lot more than 2db more gain to do that . from what i understand the potential increase in gain this style has over conventional omni antennas is due to the outside of the basket/ground elements radiating in phase with the vertical above it and also the lower TOA of the antenna . the lower TOA puts more signal going out from sides of the antenna and less going up up into the clouds . that's usually a good thing .

in a simplified example think of a antennas take off angle (TOA) in terms of water coming out of a garden hose nozzle that's pointed straight up in the air . in this example a 1/4 wave ground plane would be like having the water coming out full force as high as it will go , the water mostly gets the area right around the nozzle area wet . now adjust that nozzle so it spreads the water flow out wider and it gets a larger area around the nozzle wet . it puts more water farther out out from the nozzle , or , more signal on the horizon for a antenna . of course RF isn't effected by gravity like water is , it doesn't shoot up and fall back down , but it is dispersed from the antenna similar to the nozzle scenario . skip will reflect off the sky ....... but thats a reflection that will effect all signals when conditions are favorable . anyhow , the idea is to put as much signal close to the ground because thats where folks you're talking to are ......... unless you're talking to air planes .

a higher TOA can be a good thing for some situations , but for most folks lower is better . TOA is also effected by the antennas height , the higher the better .

 

[gamegetter]

what do you mean by "double your antenna" ? if you mean double the distance you can talk it takes a whole lot more than 2db more gain to do that . from what i understand the potential increase in gain this style has over conventional omni antennas is due to the outside of the basket/ground elements radiating in phase with the vertical above it and also the lower TOA of the antenna . the lower TOA puts more signal going out from sides of the antenna and less going up up into the clouds . that's usually a good thing .

in a simplified example think of a antennas take off angle (TOA) in terms of water coming out of a garden hose nozzle that's pointed straight up in the air . in this example a 1/4 wave ground plane would be like having the water coming out full force as high as it will go , the water mostly gets the area right around the nozzle area wet . now adjust that nozzle so it spreads the water flow out wider and it gets a larger area around the nozzle wet . it puts more water farther out out from the nozzle , or , more signal on the horizon for a antenna . of course RF isn't effected by gravity like water is , it doesn't shoot up and fall back down , but it is dispersed from the antenna similar to the nozzle scenario . skip will reflect off the sky ....... but thats a reflection that will effect all signals when conditions are favorable . anyhow , the idea is to put as much signal close to the ground because thats where folks you're talking to are ......... unless you're talking to air planes .

a higher TOA can be a good thing for some situations , but for most folks lower is better . TOA is also effected by the antennas height , the higher the better .

Subscribing to the theory that the sigma 4 is a modified form of a skeleton sleeve fed monopole, and echoed by Avanti’s advertised 1db gain over a 5/8 wave ground plane then there is gain. Avanti’s claim is specific to the 5/8 as that is probably what they compared too. For someone modifying the original sigma 4 design this gain can be affected by several variables, see Avanti Sigma4: An alternative view point… and hence the topic of this thread.


I would have a different point on “TOA is also effected by the antennas height, the higher the better.” Height is definitely better for line of sight work, but not necessary for DX. Mother nature and/or various propagation methods allow for antennas mounted low to ground to perform well on dx.

 

[BOOTY MONSTER]

............... see Avanti Sigma4: An alternative view point… and hence the topic of this thread.


I would have a different point on “TOA is also effected by the antennas height, the higher the better.” Height is definitely better for line of sight work, but not necessary for DX. Mother nature and/or various propagation methods allow for antennas mounted low to ground to perform well on dx.

i've read that thread and this thread 3 or 4 times each from end to end . i certainly didn't understand it all , but i agree there is a ton of information there about these antennas .

keep in mind im only a CB'er and most CB'er do a lot of local talking , so local performance is important to us . from what i understand dx/skip can also come in long flat reflections and that type can benefit from a higher antenna when all or most of the antenna is below nearby structures . if wrong about that please feel free to explain it to me . i have no problem with being corrected as long as im not degraded in the process .

 

[gamegetter]

i've read that thread and this thread 3 or 4 times each from end to end . i certainly didn't understand it all , but i agree there is a ton of information there about these antennas .

keep in mind im only a CB'er and most CB'er do a lot of local talking , so local performance is important to us . from what i understand dx/skip can also come in long flat reflections and that type can benefit from a higher antenna when all or most of the antenna is below nearby structures .

if wrong about that please feel free to explain it to me . i have no problem with being corrected as long as im not degraded in the process .

pm sent so not to side track this thread on "modified vector 4000"

 

[GI0ZGB]

Hi Guys, my passion for cb has been recently rekindled, it's been many years but i did once own an original sigma 4, i had also owned a fake one amongst many other antenna.
I have a few questions if anyone can help.
I am building a copy with parts i have lying around but there are a few things i am not sure about, i am going to build a gamma match but i don't know the exact dimensions of the parts, does anybody know the length of the tube and rod? Must they both be aluminum? Even if the gamma match must be aluminum could the basket be made out of soldered copper tube?
I was going to make a version from wire and suspend it between two 40M pine trees but then found that i had a large glass fiber wind surfer mast and an extendable fishing pole that fits exactly in the end, i can achieve the length required and was planning on using aluminum or copper wire, to be hung on the outside (rather than inside) of the fiberglass tubes (to avoid some shielding).
So basically the questions are:
1? Gamma match dimensions, and is alu necessary? (also is there a good source for a teflon sleeve or equivalent)?
2? Can copper be used as a basket or must it be made from alu?
3? Can the main 27' 7" radiator be copper wire? or must this also be alu?
4? Does anybody know of any interesting mods. other than the obviouse waterproofing and filing the corners of the gamma match etc?
5? Since reading some more on this forum i am wondering if a thicker radiator above the basket would benefit rather than a thin wire?

So with the glass fiber poles i should be able to get the antennae to the top of the largest 50M pine tree just behind the shack although i am probably barking up the wrong tree since i live at 1200M almost at the bottom of a narrow valley on a fairly steep hillside surrounded by 3000-4000M peaks

I must admit that i've only managed to get as far as page 16 so far on this thread, i've been up all night reading and must get to bed soon, but a few thoughts, i was thinking of making the basket out of copper pipe since it would be easy to fix together, strong (but heavy) and a smooth finish, (better in wind). But is copper going to be better and is smooth a good thing?
I was going to use wire to make the cone but it seems that from what i have read here perhaps this design may benefit from thicker materials for the cone? And what about adding a second ring larger and lower down, i know that it's not exactly practical but perhaps it's worth a try, it could hang from the 30" ring and either be grounded from above or insulated from above and grounded from below (simply attached with wire or/and nylon rope from either above or below)?

What if it wasn't a cone but more of a cylinder? Average the size of the cone and make a cylindrical sheild, groundplane? Or whatever it is?

Just some mad ideas to play with, not much mathmatical theory going into that but i've got that ground plane magnetic pull feeling thing going on

James

Hi James, manual: http://www.cbtricks.com/ant_manuals/avanti/av174/graphics/sigma4_av174_om.pdf

Had one many years ago, the only problem I had was the gamma match, changed that for an air variable capacitor fitted in a water proof box with a protruding tuning wheel, worked very well with none of the flicking swr reading in windy conditions. Currently reinforcing a new Vector 4K, it's like the early one, as delicate as chantilly lace in various places. I've machined that useless wind catcher off the top, just have to calculate the overall radiator length then I'm good to go. The build quality still won't be as good as Avanti as they used aviation aluminum, the colder it got the stronger it got. I remember discussing it with a guy from Avanti, he stated that the inverted radials prevented radiation taking place and that from the top of the radials to the tip of the antenna it radiated as a 5/8wl, silly me, I thought the radials were inductors used to cancel out the capacitance of the gamma match!Still, a very good antenna, worked well on a short stub or at two wavelengths up, and coped with lots of watts without any fuss whatsoever.
Coax Seal does a good job sealing the joints, excellent stuff.
73 Gerry.

 

[bob85]

gerry,
you must have spoken to the guy at avanti that Masterchief spoke to, it contradicts what avanti claimed, what LB.CEBIK told me about that style antenna and what cst microwave shows,

id love to hear their explanation of how you get 5/8wave radiation from the 1/2wave of monopole above their none radiating sleeve,

when you get to calculating the vertical length take into account that the upswept radials have the effect of electrically shortening the antenna,
the higher the number of radials and the closer the radials to the monopole the higher the resonant frequency for a given physical length,
the vertical needs to be longer than that calculated for dipoles/wire antennas ect, i don't know of any simple formula that includes the flared radial sleeve,

preliminary tests using a 20ft mast indicate the NEW style vector does not perform as well as the old version.

 

[Marconi]

Sounds like an

Well Bob, I hear an echo.

You've been holding out on me, I didn't know about these reports on the New Vector 4000. I just though ever body had lockjaw, about the same with all these new SP 500 that are supposed to be selling.

 

[bob85]

eddie,
its the first time i said anything to anybody,
the longer radial sleeve of the NEW vector needs testing with a propper length monopole imho,

i did notice that the new vector is a little more sturdy with fatter tubes in the upper sections but its still a whimpy construction that won't stand high wind.

 

[byder]

gamma match

one could always homebrew a copy if they had the measurements ..... and confidence to try .

Aluminum Tubing Type 6063 - 6 ft.

mmmmmmmmmm..........................
might be time to start asking/learning about gamma matches . blame bob , shock and W5LZ , LOL
are there any other omni cb antennas besides the vector and its copies and the wolf .64 antenna that use a gamma match for tuning ? what's the benefits of one over the other ? any difference it tuning ability ? tx db gain ? noise floor ? ears ?
W5LZ if i paint it pink will it make the modulation louder ?
Wolf Radio.com CB, Ham, Pirate Radio Antennas [CB Antenna]
so a gamma is just a rod that can have its length adjusted going up and down the radiator vs. a coil or ring circuling below the bottom of the antenna and being taped for resonance ?

gamma match is a simple capacitor used to adjust 50 ohms of impedance!.i made severals gamma match for yagys and dipoles and deltas and works great!