difference between gammer match, trombone,ring,and hairpin etc

[davev8]

Hi all
i have almost got all the stuff needed for my next antenna(apart from time) and almost got my head around the 4nec2 Antenna simulation software

The antennas is going to be 5/8 wave aluminium with 5/8 wave wire ground planes swept down at 30 degrees (from vertical) with a feed point of at lest 50 feet(70 will be nice) over good open ground and probably insulated from the mast and or maybe have the top section of mast a tuned length as a ground 5/8 radial, in which case the feed point will be at the bottom of this with coax going up inside the mast to the matching ring/device ( this part of the mast will be insulated from the rest of the mast below)

In the past i have always used the ring type match as on the sigma 2
Made from 6 feet long copper tube as depicted in the big Dummy's guide to CB

Now my questions
1
the ring i use is made out of 6 feet long tube but when i see on antennae like the sigma 2 etc it looks a lot smaller, so is their a optimal length? how is it worked out?
Question 1a any advantage/disadvantage to making the ring in to a big coil instead?

2
Has any of the matching device as in the title got any advantage over each other if so what?

Comments on the antenna i am going to build are most welcome

 

[BOOTY MONSTER]

Avanti AV-170 "Sigma 5/8" / "Sigma II"

the coil on the sigma 2 is not tapped like the one on the maco . i don't think it's a matching device ..... but i'm probably wrong . i did make a maco type with a tapped ring and it did better for me than one with a tapped coil . here's my 5/8 projects if you're interested in seeing what i did and avoiding my mistakes .

http://www.worldwidedx.com/cb-antennas/36898-pics-progress-homebrew-5-8-a.html
http://www.worldwidedx.com/home-brew-mods/38300-64-homebrew-temporally-finished-up-pics.html

http://www.worldwidedx.com/home-bre...oil-5-8-citizens-band-radio-base-antenna.html
http://www.worldwidedx.com/home-brew-mods/77085-progress-booty-plane-version-2-a.html

 

[davev8]

Hi BM

yes you may be correct as i can not see a tap on the ring but if you look here Avanti AV-170 "Sigma 5/8" / "Sigma II"
they say it is for matching, and the antenna is tuned by adjusting the length..... so maybe the tap is fixed inside the insulator ... i dont know

 

[BOOTY MONSTER]

maybe it's a variation of a hair pin ? i'm assuming there is no tapped coil inside the insulator since the add says "no coils to burn out or detune" . someone will come along and tell us wassup .

i wonder if the heart behind the antenna was intended as subliminal advertising ?

 

[bob85]

booty, the early sigma2 is not dc short, your braid connects to the radials and the center conducter connects to the bottom of the hoop, the bolts that hold the hoop screw into two aluminum slugs that form a capacitor across the hoop about 47pf, later sigma's had a coil inside the fiberglass connected between the hoop and radials to dc short it, the saturn uses the same setup but the coax connections and coil for the vertical are external.

 

[BOOTY MONSTER]

thank you sir . i can hardly wait for a chance to parrot that fact

 

[mackmobile43]

thank you sir . i can hardly wait for a chance to parrot that fact

That is a brave undertaking.

 

[BOOTY MONSTER]

don't confuse foolishness with bravery .

 

[mackmobile43]

don't confuse foolishness with bravery .

Touche

 

[davev8]

Hay BM
i know how the sigma 2 works.............
the early sigma2 is not dc short, your braid connects to the radials and the center conducter connects to the bottom of the hoop, the bolts that hold the hoop screw into two aluminum slugs that form a capacitor across the hoop about 47pf, later sigma's had a coil inside the fiberglass connected between the hoop and radials to dc short it,...............................

 

[BOOTY MONSTER]

Hay BM
i know how the sigma 2 works.............
the early sigma2 is not dc short, your braid connects to the radials and the center conducter connects to the bottom of the hoop, the bolts that hold the hoop screw into two aluminum slugs that form a capacitor across the hoop about 47pf, later sigma's had a coil inside the fiberglass connected between the hoop and radials to dc short it,...............................

i'll share my cracker with you

 

[Needle Bender]

I just helped a guy put up a sigma2 a few months ago and the whole ring is live from the center of the coax with a coil inside the bottom that goes to ground from the center lead. The main element measured 22 feet 4 inches for flat swrs on chanel 20. the ring was about 16 inches aruond and had about 8 inch arms holding it in place that were about 1 inch apart.

 

[Robb]

daveV8:
1
I wouldn't put it up on a 60 ft mast or tower until the bugs are all worked out. I don't know if it can be call foolishness or bravery if you do it the way you described.

2
What's wrong with buying a factory made Maco V58? Its cheap, uses a large ring type matching for low loss - as opposed to a tapped small coil - and is similar in design to the Avanti II.

You are going to use wire radials @ 60 ft up? That dog don't hunt. Better off with a Maco that has all the parts yet it is cheap enough to save you a lotta trouble. I admire your willingness to build your own. But on the other hand, it won't get you on the air without a lot of time, trouble, materials, and equipment to do the job right. So much like painting yourself into a corner - so to speak.

Now if you had a $200 antenna analyzer, the materials in front of you, done this before - then I would say 'go for it' . . . JMO

 

[Needle Bender]

Thats funny. the guy who i helped with the simga2 had a maco that was shorting out and he couldnt figure out why so he bought the sigma2 used from an old guy at a yard sale. He said its alot stronger than the maco ever was when it worked right

 

[davev8]

daveV8:
1
I wouldn't put it up on a 60 ft mast or tower until the bugs are all worked out.

No will be made an a temp 30 feet mast

don't know if it can be call foolishness or bravery if you do it the way you
described..

I don't quiet know what you mean

2
What's wrong with buying a factory made Maco V58? Its cheap, uses a large ring type matching for low loss - as opposed to a tapped small coil and is similar in design to the Avanti II.

Shipping to the UK $200+

You are going to use wire radials @ 60 ft up? That dog don't hunt. Better off with a Maco that has all the parts yet it is cheap enough to save you a lotta trouble. I admire your willingness to build your own. But on the other hand, it won't get you on the air without a lot of time, trouble, materials, and equipment to do the job right. So much like painting yourself into a corner - so to speak.

Now if you had a $200 antenna analyzer, the materials in front of you, done this before - then I
would say 'go for it' . . . JMO

>>>That dog don't hunt<<< is that American?? please explain

made the prototype (read quick and dirty bodge) 5/8 wave + three 5/8 wire radials on my house with SWR of top of my head 1-1.3 across 1.5 meg in 50 minits ...well it was getting dark, works well except when windy-SWR all over as need wire radials to be tight.

Have already started making small parts that i will TIG weld, my goal is to have the lest amount of parts clamped or bolted E.G the radator will be only 2 parts and no overlapping of ground parts like brackets etc over the radiator.

If i can figger out how to post photos on here will post a photo of the Q D B (quick dirty bodge)