5/8 wave coil

[C2]

So one thing I read is that 3/4 wave had a very high radiation angle, which is why I wanted to avoid it.

Maybe I'll just take some measurements on wire and coils...because it's fun.

I was finally able to get an Excel Smith Chart to work with the data my reflectometer spits out, so I can make graphs easier now...

Don't you just love Smith charts...?

 

[W5LZ]

Love Smith charts? Oh, yeah! I just love them to death! They are almost the very next thing to a skull fracture that I'd like to have.
- 'Doc


I hate the @#$ things! I tend to get the same information in other ways. Not as easy maybe, but a whole lot simpler for me. No self respecting bird would want one in the bottom of it's cage. If you like them, you can have my share.

 

[Simon004]

You might find 15 turns is too many.

Yeah I'll pull some wire off then before I try it out, I just found a short length of antenna wire lying around and just wound it all on, better to have it too long than too short . I'm only spending about an hour on it each day, but it's coming along nicely, just need to add the ground plane and and SO-239 connector and I should be ready for a test

Still need to work out a way to insulate the antenna from the mast though, I'll probably have a look for some thick walled PVC tube.

 

[C2]

Love Smith charts? Oh, yeah! I just love them to death! They are almost the very next thing to a skull fracture that I'd like to have.
- 'Doc


I hate the @#$ things! I tend to get the same information in other ways. Not as easy maybe, but a whole lot simpler for me. No self respecting bird would want one in the bottom of it's cage. If you like them, you can have my share.

I got other charts...pick your poison...

 

[BOOTY MONSTER]

this is a really great thread you started simon , ive enjoyed it very much , thanks for the posting .

have you considered a loop vs a coil ? kinda like what maco does or how the wizardo shows on building their 5/8 ?
Tips and tricks on how to build your own CB Antennas.

irate pirate over at quack shack tried to do it with wire but it was too flimsy so he went to a coil . ive wondered since about maybe using 1/2 inch or so copper pipe like scraps from hvac lines and homebrew some sort of plate or spokes to keep it centered in real heavy wind .
or using copper pipe with reducers for sliding sections and hose clamps and do something similar to the trombone tuning like jay does on the i10k .

it seems the 6 1/2 inch difference in length makes pretty much no difference in real world antenna performance . other places...........

i soooo wish i could find a place around richmond that sold aluminium tubing !
you would think being the capitol of the state and a fair sized city............????

 

[C2]

I think 1/4 inch copper tubing would work fine for building a large, single wind coil, like the Maco...

 

[Simon004]

thanks Booty, I only started the thread, it's the people who replied that really made the thread

I did consider the open coil approach, but I really don't have the tools to fabricate something like that, so it was quickly dismissed. I suppose it could be quite easily done though if you could bend some copper pipe into a circle. My tools are limited to a drill, a saw and a screwdriver really, lol. I spent a few hours on it today and I'm nearly ready for testing. Its all a bit Heath Robbinson at the moment, this is the first time I've made a verticle, apart from a 1/4 wave about 15 years ago. I've made a couple of quads before, I've wanted to make a Yagi but the main problem is obtaining aluminium tubing, which has been the same with this project. I actually have somewhere I can buy it from that is only 5 minutes drive away from my house, but the prices they charge just doesn't make it viable to use, it would be cheaper just to buy a ready built antenna than to buy the parts. I suppose it's because the antenna manufactures buy in such volumes that they get a better price than me just wanting to buy the odd length.

I looked around for some aluminium plate to suport the ground planes and I couldn't find any anywhere, unless I wanted to buy a 6' x 4' sheet of it, even if I did that I couldn't cut it down to the size I need so I ended up using some pine skirting board I had in my shed to support the ground plane with, hehe. It's made the antenna a bit heavyer than I wanted, but it should be ok I hope. One added benefit from using the wood is that now I don't need to isolate the antenna from the mast at all. The 4 ground planes are completely isolated from the mast anyway. The antenna isn't going to be a permanent installation, it's really a replacement for my A99 that I would put up when I go /p on top of a hill, so I've made the ground planes so that they will fold upwards while being transported. I'll try and get some pics on here soon seeing as I'm nearly finished now and report back with how it works, providing it does actually work, lol.

 

[W5LZ]

Bending metal isn't really that difficult, I do it all the time! Sometimes even intentionally.
Have something round that's approximately the right diameter? Waste basket, jar, flashlight, whatever? Of course that just depends on what kind of metal you are trying to bend too. Copper tubing, ain't no 'thang'. Cast iron bar stock, forget it, find something else. It doesn't have to be perfectly round for a coil to 'work'. It looks nicer, but only to some arbitrary point.
This is called "shade tree'ing", "RedNeck'ing", "Thinking outside'a da'box". Basically, the same thing all them antenna manufacturers do the fist time they make one.
- 'Doc

 

[RickC.]

If you don't want to mess with the copper tubing (which is not hard to work with, really), you could try heavy bare copper wire, #8 or larger. I used either #8 or #6 on the 5/8 I made a few years back, can't remember now.


Rick

 

[C2]

My tools are limited to a drill, a saw and a screwdriver really, lol.

Get you a hammer!

 

[Simon004]

Get you a hammer!

lol, I do have a hammer too, I just didn't need to use it for this project I just meant to say my tools are limited, no specialist stuff found here.

I suppose it's not that difficult to make a tuning ring, and it might be something to try in the future, but I had some wire so it was easyer, faster and cheaper to make the coil. This is just a prototype really, just using what I have available in the junk box. As with all my projects, once I get it working I'll keep adding and finding ways to upgrade and improve (hopefully).

 

[BOOTY MONSTER]

on that wizardo 5/8 they suggest building the coil with a 6 ft peice of wire . but most wire is too floppy . for experimenting or just to see if itll work a 17-18 inch diameter plywood donut (with the hole off center so the coil will evenly surround the radiator slightly underneath it) could be used as a former with the wire loop held on the outside with nylon ties might work .
i noticed sirio actually uses a square or rectangular loop on their 1/2 wave .

 

[BOOTY MONSTER]

WOW !!!!!
and i thought i used a lot of silicone on my lil wire contraption . lol
looks good though . ive been thinking about aluminium strips for the coil . lowes here sells it in a few different sizes up to 8 foot .
im sure Doc will approve of the red coax , it makes a lot of difference ! hehe

BTW , if i recall correctly on a 5/8 antenna having sloping or horozontal ground radials doesnt make a noticable difference ..... correct ?

and 4 or 5 foot ground radials vs. 9 foot ground radials dont make a difference either . is that also correct ?

 

[W5LZ]

Actually, the red/redish/pink color only works with the radiating portion of antennas, not with the feed line.
A word about silicon. There are different kinds. If it smells vinegary it has an acidic content that's not very good for electronic or metal stuff, eats it. It'd take a while, but if it smells like vinegar it will eventually not be good for whatever it's on. If I remember correctly, the non-vinegary silicon is the water proof, or marine stuff?
Coils, their shape. That flat-strap type coil can contribute to mechanical strength, but don't expect any electrical benefits. If you like the looks of it then use it. You might round off any 'sharp' edges before bending it though. Probably no noticeable differences, but sharp edges or pointy things are contributors to noise production or corona discharge.
- 'Doc

 

[jazzsinger]

Actually, the red/redish/pink color only works with the radiating portion of antennas, not with the feed line.
A word about silicon. There are different kinds. If it smells vinegary it has an acidic content that's not very good for electronic or metal stuff, eats it. It'd take a while, but if it smells like vinegar it will eventually not be good for whatever it's on. If I remember correctly, the non-vinegary silicon is the water proof, or marine stuff?
Coils, their shape. That flat-strap type coil can contribute to mechanical strength, but don't expect any electrical benefits. If you like the looks of it then use it. You might round off any 'sharp' edges before bending it though. Probably no noticeable differences, but sharp edges or pointy things are contributors to noise production or corona discharge.
- 'Doc

You can't argue with the man that came up with this high tech coil design.Sorry Doc,just couldn't resist it,pmsl.QUALITY.