Avanti Sigma4: An alternative view point

[wavrider]

CDX-007,

Working on a different idea, I really don't like traps if I can use long enough elements.

Having the 1/4wl vert with two .1875 wl, wires, coming down from the top of the vert at a 30 degree angle. OR as close to that as I can make it.

Reading in the low band wire antenna books they have shunt fed towers with this configuration and moving the wires closer together or farther apart changes the impedance allowing a good match, and claim some directivity in the direction of the wires or so called 30 degree inverted V coming down from the top of the vert.

Hi-jacking the sigma thread though, apologize about that, if I ever get past the "thinking" phase of this project will start a new thread.

 

[muzzle_blast]

Hello folks! I'm new to this forum but have found LOTS of great information. This thread in particular is the one that got me to join!

I'm getting back into CB radios because I have stumbled across some deals I just flat out couldn't pass up and I asked my pop, "what would be the best antenna without setting up a beam?" His immediate answer returned "SIGMA 4"

He swears by this setup and he has talked on all kinds of stuff. I remember PDL's, Stardusters and Sigma's. He had many others also but he was always impressed with the Sigma 4. He said he could out talk people all the time with "better" antennas. So now I'm on the lookout for a Sigma 4 (or equivelant)...

I have read thru this thread and have seen some hates twards the "copies". Remember I'm a young pup and have a family so funding is somewhat limited. Any help would be appreciated. If anything I could even open up another thread for this discussion! Any input is much appreciated!!!!!


Thanks in advance!

 

[radioman24]

To answer your question, you can not go wrong with the sirio vector 4000 they are just like the original sigma 4 and made in Italy H&Y ELECTRONICS sells them for a great price and there all new and improved!!!

 

[kevin IB/379 Stringbean]

deleted

 

[bob85]

muzzle_blast, welcome to the forum, your pop gave you good advice,

the vector 4000 is an inexpensively constructed antenna using the same principles of operation as the sigma4,
in my experience the old so called 7/8wave vector 4000 performs better than the sigma4 when tuned correctly,
i can't say if the updates sirio have done to the new vector match their claim of an improved lower radiation angle,
the principles they have used are known if you look beyond the "big dummys guide to cb radio"

sirio are not near the quality of the avanti sigma antennas,
sigmas used 6061-t6 drawn tube with a .058" wall, sirio use less expensive and thinner 6063-t832 tube in metric sizes with about .049" wall in the radial sleeve and upper sections,

some say the vector is the best bang per buck out there, thats not true,
the vector tuned right is the best bang cb vertical at any price available today

 

[DIRTYWHITEBOY]

Its a Interceptor 10-K WORLD!!!

Looks like a retard has invaded this thread.

 

[mackmobile43]

Looks like a retard has invaded this thread.

Speaking of this thread what are your finding on the lw-150.

 

[Dr_DX]

muzzle_blast, welcome to the forum, your pop gave you good advice,

the vector 4000 is an inexpensively constructed antenna using the same principles of operation as the sigma4,
in my experience the old so called 7/8wave vector 4000 performs better than the sigma4 when tuned correctly,
i can't say if the updates sirio have done to the new vector match their claim of an improved lower radiation angle,
the principles they have used are known if you look beyond the "big dummys guide to cb radio"

sirio are not near the quality of the avanti sigma antennas,
sigmas used 6061-t6 drawn tube with a .058" wall, sirio use less expensive and thinner 6063-t832 tube in metric sizes with about .049" wall in the radial sleeve and upper sections,

some say the vector is the best bang per buck out there, thats not true,
the vector tuned right is the best bang cb vertical at any price available today

My experience would tend to agree with Bob85 from a performance standpoint. It was the best receiving vertical GP antenna I have used. My I-10K does as well or better on TX due to the lower losses in the matching network.

But after my 3rd Saliut LW-150/vector 4000 went down due to ice build up on the main vertical, it was time to put up a stronger antenna. I originally went with a Maco 5/8 which didn't perform as well but it lasted about 5 years before the ice got it too. After I put up the I-10K, I haven't had any more problems; the reinforced center radiator is able to handle the ice and high winds.

The LW-150 is a "dirtier" antenna. Since the matching network (gamma match) is below the ground radials, it isn't "shielded" and you have a lot more RF going below the antenna.

IMHO, even though it is probably the best RX ground plane, the thin wall aluminum just doesn't hold up. My best bang for the buck would be a Workman W-58 (re-branded Maco 5/8) for less than half the price of the Vector 4000. Not the best performing antenna, but definitely the best from a cost vs. performance ratio.

 

[Shockwave]

My experience would tend to agree with Bob85 from a performance standpoint. It was the best receiving vertical GP antenna I have used. My I-10K does as well or better on TX due to the lower losses in the matching network.

But after my 3rd Saliut LW-150/vector 4000 went down due to ice build up on the main vertical, it was time to put up a stronger antenna. I originally went with a Maco 5/8 which didn't perform as well but it lasted about 5 years before the ice got it too. After I put up the I-10K, I haven't had any more problems; the reinforced center radiator is able to handle the ice and high winds.

The LW-150 is a "dirtier" antenna. Since the matching network (gamma match) is below the ground radials, it isn't "shielded" and you have a lot more RF going below the antenna.

IMHO, even though it is probably the best RX ground plane, the thin wall aluminum just doesn't hold up. My best bang for the buck would be a Workman W-58 (re-branded Maco 5/8) for less than half the price of the Vector 4000. Not the best performing antenna, but definitely the best from a cost vs. performance ratio.

To get rid of the "dirt" in the Sigma design simply install a coax choke at the feedpoint. The Sigma does cause more RFI then a 5/8 wave if you don't because the coax tends to radiate. I can confirm the choke on this antenna does make a difference at HF and reduces RFI to the level of a 5/8 wave with full radials.

When it comes to full length antennas, to say one hears better then it transmits is probably less then accurate. If it's rated at 1.2 db, that's 1.2 db in transmit as well as receive. About the only antennas that fit that description are small ferrite bars or receiving loops.

 

[mackmobile43]

To get rid of the "dirt" in the Sigma design simply install a coax choke at the feedpoint. The Sigma does cause more RFI then a 5/8 wave if you don't because the coax tends to radiate. I can confirm the choke on this antenna does make a difference at HF and reduces RFI to the level of a 5/8 wave with full radials.

When it comes to full length antennas, to say one hears better then it transmits is probably less then accurate. If it's rated at 1.2 db, that's 1.2 db in transmit as well as receive. About the only antennas that fit that description are small ferrite bars or receiving loops.

good to know

 

[Dr_DX]

When it comes to full length antennas, to say one hears better then it transmits is probably less then accurate. If it's rated at 1.2 db, that's 1.2 db in transmit as well as receive. About the only antennas that fit that description are small ferrite bars or receiving loops.

We're not talking about full length antennas. We are talking about a 7/8 wave vs. a 5/8 wave. The additional 1/4 wave length of the vector's vertical radiator gives it an RX advantage (more capture area) but it's TX radiation angle and lobe pattern isn't as good as the 5/8 wave. The direct trombone style match is more efficient than the capacitive gamma style match.

 

[muzzle_blast]

Thanks for the info guys! And thanks for the welcome to the site!

I have been doing a little research here locally and have discovered that probibly 75% of the people around here are running an IMAX 2000 with the groundplane kit... I haven't thumbed through the threads to see about this antenna yet but, is this one compairable in performance to the Sigma4???

Also what kind of tuner would you guys recommend for around the $100 range (if there is one LOL)

 

[bob85]

reciprocity

 

[CDX-007]

Its a Interceptor 10-K WORLD!!!

Actually, I fear it's still more of an Antron99 world, performance be dammed!

And I just got interesting results from a number of tests I did last weekend, see my sig.

 

[bob85]

now that really does surprise me:blink:, your daddy's penetrator ohmy,
i cant explain that result 007, its sure to ruffle a few feathers,

are we tuning our i10k's incorrectly?, did you check them with an analyser?,
maybe we need 50ft of lmr400?,
i dont see a hat on the i10k?

dont worry, theres still only two of us that tune the sigma style antenna correctly, my antenna fears no 5/8wave groundplane,
it talks to and receives in equal measure stations beyond which any 5/8wave i ever owned can reach ( not including my avanti saturn which i have not tested ),

thanks for doing the test