BOOTY 4

[HomerBB]

Booty, Marconi makes some great points on the dimensions of the V4k. They are critical. I have reconsidered my experience with the one I built, and it is true i could not get it to tune properly without reworkinf the Gamma location from top to bottom. It seemed I had to male the gamma fit directly between two of the radials exactly centered at the exact distances from the center vertical along its entire length as the radials were from the center vertical. Whem making the antenna it struck me odd at the time how that on 11 meter Yagis the gamma needed to be set at about 4" out from the driven element, but this antenna needed to be at an angle so close and distant from end-to-end.

What plagued me most with this antenna is that, as Marconi said, without any other way of measuring my success with the antenna except to a 5/8 wave, Ihad no real way of knowing whether my Qv4k was actually what it should be. I will get back to it soon and see if I like it more. A 5/8 is a simple antenna by comparison.

 

[Marconi]

Booty, Marconi makes some great points on the dimensions of the V4k. They are critical. I have reconsidered my experience with the one I built, and it is true i could not get it to tune properly without reworkinf the Gamma location from top to bottom. It seemed I had to male the gamma fit directly between two of the radials exactly centered at the exact distances from the center vertical along its entire length as the radials were from the center vertical. Whem making the antenna it struck me odd at the time how that on 11 meter Yagis the gamma needed to be set at about 4" out from the driven element, but this antenna needed to be at an angle so close and distant from end-to-end.

What plagued me most with this antenna is that, as Marconi said, without any other way of measuring my success with the antenna except to a 5/8 wave, Ihad no real way of knowing whether my Qv4k was actually what it should be. I will get back to it soon and see if I like it more. A 5/8 is a simple antenna by comparison.

Homer, let me mention that I've checked the particular angle of the gamma on my A. S. version of the Sigma4, with three legs, and the gamma is not in precisely the same plane as the radials. This may be an example of what Bob and I have suggested regarding both of your homemade projects for this antenna. This may also be true with other designs as well, because I'm reminded the obvious differences I've noted with several different knockoff Starduster type antennas over the years...where the knockoff's all had radials set at at 40-45* degree angles or more.

 

[HomerBB]

What a deal. clearest picture of those parts, yet. . . just go for it and see Booty.

 

[BOOTY MONSTER]

thanks guys . made a few changes to the lower bracket . the 1/16 is too thin for the stud to tighten down properly so i used a piece of the 1/8 as kind of a shim . but i did get the feedpoint about 1/2 inch from the vertical now .

i also spread the fins for the basket elements out a little wider too . the bottom of the elements should be within 3/8 or less of each other around vertical . i am going to make a better lower bracket , but im hoping this has a much better chance of working properly now .

heres a pic of the gamma attached to the stud . the angle is off , but it shows how it will attach . the rod is 3/8 inch solid and the tube is 1/2 inch inside and 5/8 outside . the tube is 10 inches from the top to the bottom , not including the little foot for its attachment with the 3/8x24 bolt . the second roll of teflon tape wasn't enough . i ran the teflon up to 12 inches from the bottom for some overlap . it has about 10-12 layers of teflon tape and since i didnt want to make a special trip just for a 3rd roll of teflon tape i finished fattening it up for a nich snug fit with some 3M+ electrical tape rated for 0 to 200 plus degrees F.

i notice a few comments here and there about the vertical flexing and breaking or moving the tuning of the gamma match . im pretty sure i wont have that problem with the 1 5/8 inch bottom tube . i'll use a slit on the tube and a hose clamp to hold it in place . ill use some heat shrink tubing over the tube/rod but under the hose clamp for weather proofing once im happy with the tune/performance .

thanks again guys , your suggestions are appreciated .

BTW , does anyone have or can link/post a pic of a 4 element version that clearly shows the proximity of the gamma at its top connection point ?

 

[bob85]

i doubt it will be the last antenna you make booty, you seem to have the bug,

good to see its comming along, you moved the gamma closer at the base like the original, my old vector gamma strap measures 5-5/16" from the inside edge of monopole to outside edge of gamma rod measured on top of the strap,
be interesting to see if the gamma works ok

still don' know where i put my hub

 

[BOOTY MONSTER]

thanks for the comments bob , and im glad you didn't see any potential problems worth mentioning . i pm'ed shockwave about the gamma , he said the 10 inch tube and 30 inch rod should be able to tune the antenna . im planning on attaching the arm for the top 27 inches up from the lower bracket

im guessing that he's assuming i dont screw up other areas of it .

 

[BOOTY MONSTER]

messed around with the basket support today . it is about twice as heavy as i thought it would be . i think ill make another one next month when i make a different lower bracket , but it'll do what i need it to do till then . i just cut up the plastic lumber boards i used on my 5/8ths . its piece of the 5/4 thats 5 3/8 inch square with a 1 1/2 hole in the middle . the arms are just 1 inch strips of the same material .

im gonna get some nice thick zip-ties from my bro-n-law (same one that got me the 1/4 inch copper tubing) that does HVAC . the black ones looked adequate in the store , but installed they look way too weak .

i did see shockwaves comment about the basket support height in jays' A1 antenna section .......

........................... Even though there may be some temptation to raise the height of the four radial insulators to gain loop support, you'll want to avoid this in high power applications. There is extremely high RF voltage present between the top half of the radials / loop section and the main radiator. Moving the insulators higher then half way up the radials will cause corona arcing across the insulator when wet at around 10 KW. Teflon may not cure the problem here since it's the addition of snow or rain that reduces the insulation properties. ......................

http://www.worldwidedx.com/a1-antennas/57685-how-about-making-sigma-4-style-antenna-2.html post 14

but since i only run a 2 pill max it shouldn't be a issue for me or if i happen upon enough extra money to put into a 1K or 2k amp after more important stuff though
the 1 1/2 inch tube fit nicely in it

ill cut and grind down the screw points later .

ive also got an idea to keep the basket from twisting . but what im really keeping an eye out for is about a 20ish inch square or disc diameter of thick plastic or nylon . a big ol kitchen cutting board would be ideal i think ...... if it passes my high tech microwave test
id like to put it at about 5 1/2ish feet up right where the basket elements go from the 5/8 tubing to the 3/8 rod .

 

[joejoenikk]

If they don't get the message after that one, try a AR15.

Donno Booty...seems that improving that desighn would involve using good aluminum...that was the real problem with the vector, they didn't survive. 7075 is at least two time if not three times stronger that the architectual crap they all use. It's actually stronger than 316 stainless steel NOT EVEN POUND PER POUND STRONGER PERIOD. it's closer to drill bit steel than aluminum. (It, of course, also costs twice+ as much.)

I was considering building a 5/8 grounded loop with a reflector. What I'm tring to do is a little weird. I live in Florida on a beach. I want to be able to shut down all of that skip I get all afternoon from the Gulf of Mexico. I'd enjoy talking back, but if noone ever told you, the ocean/limestone doesnt provide much of a ground plane, I need to put mesh down just to talk local. I think I'd do better if I aimed a beam strait up in the air. There is so much salt in the palm trees that I can't get a cell phone to work when I'm looking at the repeater tower. (And O!, when the alligators arent eating my D104, the Thunderstorms roll through just about every day.)

Have any of you guys ever tried to build a extra wide beam?

 

[BOOTY MONSTER]

welcome to the forum joe .

im using Type 6063-T832 drawn aluminum tubing from DX Engineering .
Aluminum Tubing Type 6063 - 6 ft. unslit ends

the vertical will consist of six 6 ft sections going from 1 5/8 diameter at the bottom to 1 inch diameter at the top . hopefully it will be strong enough . IF .... if it fails the plan is to keep 6 ft sections for the two bottom sections , but go with 3 ft sections for the remaining length for less wind load .

im not at all familiar with a "5/8 grounded loop with a reflector" type antenna , but id be interested to learn if you will explain the design . i also dont know what a "extra wide beam" would be since the driver is a dipole and the directors/reflectors have increasing and deceasing element lengths of %105 depending on how many and where they are on it . i know sometimes have been used on beams to reduce the elements lengths , but coils always reduce the performance when used to shorten a 1/4 wave length element .

be sure to share your build when you make it

 

[Marconi]

i doubt it will be the last antenna you make booty, you seem to have the bug,

good to see its comming along, you moved the gamma closer at the base like the original, my old vector gamma strap measures 5-5/16" from the inside edge of monopole to outside edge of gamma rod measured on top of the strap,
be interesting to see if the gamma works ok

still don' know where i put my hub

BM, my AS version of the Sigma4 also has 5-5/16" at the same point.

 

[BOOTY MONSTER]

thanks for that info 'ol grandpa . so both versions have the same distance out for the gamma tap . that's where ill put mine too . i want to change the tabs on the ring to 1 1/2 inch wide strip and use 2 bolts on the ring and 2 on the tube to reduce the twist potential of the basket and make the connection physically stronger . im also going to change the bottom bracket . and im not really happy with the stand off ........ so thatll be changed too . i dont think any of these changes will have any effect on the tx/rx of the antenna , but just make it more durable and solid .

since im a poor duck i just can't put any more money into it this month so ill have to wait a few weeks to finish it . oh well ..........

 

[BOOTY MONSTER]

i think im gonna cut my old mounting plate into a 8 sided 4 inch wide octagon .

the circle isnt perfectly centered , but the x is . the circle is just to show where it will be . the short lines inside the long clipped corners are 1 1/2 inches from the x and about 5/8 inch from the side of the vertical when its in it , they will be the attachment points for the bottom of the basket elements on top and for L shaped brackets clamped underneath to secure it to the vertical . i'll probably mount my coax stud on the other side of where the hole is now centered between the edge and the side of the vertical . that will keep the entire gamma inside the basket , and hopefully have minimal or no effect on the antennas RF distribution pattern .

opinions ???

 

[BOOTY MONSTER]

made some new bracket pieces to go between the tubing and the ring . and between the tubing and the bottom plate/bracket . and also to mount the plate/bracket to the main vertical .

the top 2 will go on the ring . i need to make 2 more but i dont have anymore of the 1 1/2 by 1/8 inch thick strip . tonight or tomorrow night ill go by my bro-n-laws and use his metal break to make some clean sharp bends where i want them to go on the different pieces . ill get the extra 1 1/2 strip and make and put them on in a few weeks . they will also have a very slight (5-7ish degree) angle

the reason for the slit and the hole in the top pieces is to be able to put a slight opposing twist to kinda follow the curve of the loop . there will be a 1/4 inch ss nut/lock washer/bolt on each side about where the black dots are . ill make the slits in the 6 inch tube sections about a inch longer and use 2 ss n/lw/b there where the tube connects at the bottom . i'm thinking with the other 2 ill make it'll lock the basket/radial connection tight enough so i dont have to worry about the single n/lw/b (like i have now) allowing the whole basket to twist in the wind . i also have an idea using the X to help prevent that also .

the 4 pieces in the middle are for the bottom basket elements to connect to the bottom plate from the previous post . they'll just be bent 90 degrees on the line with 2 ss n/lw/b securing the bottom of the 5 1/2 ft tubes . the hole in the bottom will be to bolt it to the plate approximately where the short lines are , 5/8 inch from the side of the vertical .

the 4 pieces in the middle are for the bottom basket elements to connect to the bottom plate from the previous post . they'll just be bent 90 degrees on the line with 2 ss n/lw/b securing the bottom of the 5 1/2 ft tubes . the hole in the bottom will be to bolt it to the plate approximately where the short lines are , 5/8 inch from the side of the vertical .

the bottom 4 pieces are for attaching the plate to the vertical . the plate will hold the the bottom of the basket elements and the mobile stud for the coax/gamma to attach . they will be bent 90 degrees across the middle of the hole . the solid tab at the top will attach to the same n/lw/b that the bottom element bracket uses through the plate . the reason for the hole and slit is because the 1/8 inch stuff is really really stiff across its length and hard to bend/curve . using the hole and slit i can both get it closer to the vertical and also slightly twist them around the vertical for more surface area contact and also spread the pressure more evenly around the bottom 1 5/8 tube to keep from squashing it square . ill just cut the plate to a 4 inch square and mount the tabs with it on the vertical and then make lines to trim the excess so its as small as possible .

for anyone considering a antenna project that requires cutting metal i very highly recommend using a black fiber metal cutting blade . after i cut stuff with circle saw it's very handy to gently use the side of the spinning blade to round the corners and shape the edges roughly knocking off the burrs . it cuts down a lot on the hand file work to . also , using vise-grips to hold the short pieces when cutting both keeps your hand farther away from the spinning blade . and trust me when i tell you this stuff gets really hot when cutting/shaping so it help keeps fingers from getting scorched

 

[HomerBB]

Lookin' good. Keep it coming.

 

[BOOTY MONSTER]

i just went and got my stuff bent , the aluminum got bent to .

im thinking the split bottom pieces with the hole are gonna loose their legs when i try to bend them to contour to the vertical :headbang. hind sight being 20/20 i probally should have used the big break in the back instead of the 4 footer . its wont cut into thicker material cause the blade set back is adjustable . oh well . if they do ill just re-make them but with the 1/16 strip . its much more friendly to bending and flexing . even just 2 of them would be plenty strong , but i'll do 4 ....... because i can .