Home-Brew Sigma 4

Do you enjoy making your own equipment or antennas? Discuss construction and design in here.
BOOTY MONSTER
Regular
Regular
Posts: 23
Joined: 03 Mar 2009, 19:19

Re: Home-Brew Sigma 4

Post by BOOTY MONSTER »

some pics of the latest changes .
my tubing came so i can double wall the two bottom sections . the first will be 1 7/8 diameter and the second will be 1 5/8 , each higher section will be single wall . all tubing is 0.058" wall, 6063-T832 drawn . i changed the tabs holding the bottom of the ground/basket elements to the 1 inch x 1/8 inch strip instead of the 1 inch x 1/16 , moved the tabs and clamp to hold the plate assembly to the main vertical to underneath to clean up the top section .
a few more minor changes to come .

Image

Image

Image

what i had before ...

Image

User avatar
bigpimp347
Legend
Legend
Posts: 8422
Joined: 08 Aug 2009, 10:23
Location: J26 Nottingham
Contact:

Re: Home-Brew Sigma 4

Post by bigpimp347 »

i love how you made the gamma match/SO-239 part, why didn't avanti or sirio think of that idea ???

i've got loads of those aerial mounts, might be an idea to change them..!!
http://livecbradio.co.uk UK's only 24/7 live stream

User avatar
M0MTH
Radio Addict
Radio Addict
Posts: 680
Joined: 21 Nov 2008, 00:06
Call Sign: M0MTH
Location: Derby
Contact:

Re: Home-Brew Sigma 4

Post by M0MTH »

brilliant, well done :-)

BOOTY MONSTER
Regular
Regular
Posts: 23
Joined: 03 Mar 2009, 19:19

Re: Home-Brew Sigma 4

Post by BOOTY MONSTER »

[QUOTE=BOOTY MONSTER;308072]humid as heck today ... but i got a little done after the honey do list was finished .

Image

changed the way the basket supporting X mounts so it locks into place and doesn't have but maybe 3/8 of an inch of wiggle out where the elements pass through .

heres a look at how the top of the double walled bottom section looks with my homemade clamp on it .... it's actually 4 walls thick from there to 12 inches down . the clamp is 1 1/2 x 1/16 strip with 1 x 1/8 tabs to keep the 1/16 from bending and tearing when the bolts are tightened down .

Image

i neatly filed down the hole in the x support so the 1 5/8 tube snugly fits in it . i also notched it so the bracket lockes it in place .

Image

i also got my bottom plate clamp made . its two pieces of 1 x 1/16 with 2 inch tabs .

Image

it'll definately be cleaner up top where everything attaches too .

Image


Image

its not tightened down and not at its final place on the vertical .... but thats how it goes together .[/QUOTE]

CA148
Super Member
Super Member
Posts: 167
Joined: 22 Nov 2008, 13:43
Location: Stockport UK

Re: Home-Brew Sigma 4

Post by CA148 »

Right get it up on mast, lets see how it works, I remember back in 1983 having the original Avanti Sigma IV up, on top of a 20ft scaffolding steel pole, it looked like a medium wave broadcast tower, bloody huge, the top of the antenna reached up higher than the local flats, worked superb until gale force 70mph winds brought it all crashing down, cracker antenna though but too big.

BOOTY MONSTER
Regular
Regular
Posts: 23
Joined: 03 Mar 2009, 19:19

Re: Home-Brew Sigma 4

Post by BOOTY MONSTER »

got a little more done .....
here's the bottom bracket with the basket elements attached . with the exception of the so239/stud mount and the gamma its finished and i have no further plans for it . :thumbup:

Image

here's another pic of the under side of the X locked in place with by the home made clamp .

Image

and here's a pic of the top of the X with the home made clamps made from re-purposed u-bolts and re-purposed 1/8 inch aluminum strip from a previous antenna project . these suckers hold tight and dont strip like the little hose clamps :thumbup1: . they clamp the top 3/8 basket rod to the lower 1/2 inch tube and also lock the X at the top .... so the X has no twist and can't move up and down either , its locked firmly in place .... which also locks the basket elements firmly in place . i'm finished with that part too :thumbup:

Image

i used the same clamps for the top too . i still need to cut down the bolts holding the ring on . ill replace them with 1/4 inch #8s if i change the ring to a different size ... or if i get rally bored and have nothing else to do . but that's pretty much done too . :thumbup:

Image

i'll make another gamma arm to fit the larger bottom tube tomorrow and put the gamma on . i may mess with the pipe idea i have for mounting it to a mast to .

rigmo
Registered New User
Registered New User
Posts: 1
Joined: 11 Jan 2020, 21:51

Re: Home-Brew Sigma 4

Post by rigmo »

Hi SIR, Guys...
I need to tray make for anther band... any calculator or construction plan formula?

thank you in advance..
p.s
all photos missing

Post Reply