Homemade verticle?

[PONY EXPRESS]

Thanks for all the help! I really appreciate it!

tickdog, I meant to say I smashed the end of the copper wire enough to drill a hole into and hold it to the wood. The copper wire is the ring I made that connects to the antenna with a bolt near the bottom. The braided part of the coax is connected to the bolt in the wood and soldered to the radials. This is where im lost. Should the end of the copper wire bolted to the wood be touching the part of the braided coax? Wouldnt this be shorting it out? I just followed exactly how the instructions showed.

And about the pole.. I think I lost about 50 lbs trying to tune this thing

IT IS MUCH BETETR to mount it 5-7 ft off the ground 1st and get a close match before you put it up at its final nesting height

[nutcracker]

That is what I did, I took it down for now until I can figure out whats up with it. I think The ring does need to be longer like doc said though, because the swr does get better when it goes twords the pole and alot worse when its farther away.
Anyhow thanks for clearing that up doc, now I understand the difference and may try that 1/2 wave this winter.

[drdx]

Just understand that the 1/2 wave he was referring to is a dipole, not a single vertical element that is a 1/2 wave long. A 1/2 wave vertical element will not give you a friendly feedpoint. A 1/4 and 3/4 will. 3/4 offers a bad pattern but the magical 5/8 is great. Other than the ring, you could do the 5/8 tall vertical piece and make up for the rest of the length making it the needed 3/4 (for a good match) via base loading it with a coil that you can vary the tap point (where the coax connects) for the best swr. It may be a little less frustrating than the ring approach. -drdx

['Doc]

Yes, the 'other' end of that wire should connect to the ground bolt. I know it seems like it would be a 'short', and at DC it is, but not at 27 Mhz. Has to do with how RF alternating current 'sees' things. Supporting the coax on that board everything is connected to is also a good idea, tape it or something. If the coax moves around it changes the relationship between it and that wire ring, which would mean it's also changing whatever 'match' the thing is presenting to the radio, and sort of 'deforming' the ring etc, which just means more unintended 'changes'.
And just to sort of clarify things a bit (or make them more complicated, depending on how you look at it), that 'ring is electrically the same thing as a coil. The braid is connected to the bottom end of that coil and the center conductor is making a connection on one of the turns that make up that coil. What that does is present a 'variable' inductance to properly match the 50 ohm feed line to the less than 50 ohms antenna. As the center conductor tap moves closer to the antenna part, it's adding more inductance (coil) between center conductor and braid, and less inductance between center conductor and antenna. Somewhere on that ring, you'll find a 'sweet spot' that's just the right combination to make that antenna appear to be 50 ohms to the feed line (or close enough not to make any difference). When you find that spot, quit moving the center conductor!
Now for the 'catches'. The indicated SWR may never get to some arbitrary, 1:1 point. Close, but not exactly there. If it gets to 1.5:1 or below, quit while you're ahead. It'll work just fine. Another 'catch'. Tuning an antenna from ground level is very nice and convenient! Unfortunately, since everything around an antenna affects it's 'tune', moving it higher is going to change it's state of tune. It's always best to tune an antenna where it'll be used. Not very convenient, but still best, things don't change much then. One 'trick' is to tune for a very slightly higher frequency than you really want. That usually puts it back to a lower frequency when you raise it to where it's going to 'live'. If you want to sort of 'tweak' it after you get it to it's new 'home', that's fine, you're the one going to have to climb that pole, not me!
Have fun!
- 'Doc


(I'm a genius cuz I thought of all this stuff, right? ... I wish! It's because I've made the same sort of mistakes before, at least twice, and that's why I hate ladders. But just THINK! After this, you too can say, "Been there, done that!". Oh, wont that make the whole process worth while?! )

[nutcracker]

Well the antenna has been up for a few weeks now doing nothing, so i was looking at the 1/4 wave ground plane, so with a few minutes of collapsing the 17' antenna down to 102'' and putting new radials on it it became a 1/4 wave antenna. First swr came out to 2 which I was quite amazed by. With a little tuning I have a swr of 1.3 on channel 20. Im quite pleased, but how good is this antenna? And could I make a 1/2 wave lenght by the same concept just making it larger?

['Doc]

The quick-n-dirty answer is no. The reason for that is because of the input impedance of an end fed 1/2 wave length antenna is more like 1000-2000 ohms instead of the 50 ohms your radio want's to see. Bummer, right? Not really! Think about this...
A vertical dipole (or a horizontal one) is a 1/2 wave length antenna. You got a 1/4 wave on one side of the feed point, and another 1/4 wave on the other side of that feed point. Nor if you were to take that bottom 1/4 wave part and split it into 3 or four 1/4 wave thingys by splitting it long ways, then move those bottom 1/4 wave section mor horizontally, what do you end up with? "I'll be dipped!", you got a 1/4 wave groundplane antenna, don't you? So, if you want to 're-shape' that 1/4 wave groundplane antenna you have into a center fed 1/2 wave antenna, it just isn't gonna be that much of a deal, will it. Or just make another antenna, leave your 1/4 wave'er alone, it works.
There are a couple of 'catches' though. Making that feed line comee off of that vertical 1/2 wave horizontally (close to 90 degrees from the antenna) is a very good idea. It means less induced current flowing on the outside of that feed line, which is called 'common mode current', which usually means it's gonna get back to your radio and that's not good, sparks off the mic, etc, interference to electronics in the house and so on. The further you can make the feed line come away from the antenna before starting to paralleling it is more better.
Then again, if you want to go to the trouble, you can end feed a 1/2 wave length antenna. It's done quite often, as in an 'A99', for instance. You can do that by means of using a couple of coils. Lots of adjusting with that, no simple way around it unless you want to just copy that 'A99' matching thingy at the bottom.
Would there be a difference in performance? Sure. How much, and would it be worth the trouble? Beats me, that's up to you.
- 'Doc

[nutcracker]

Thanks for the info again doc! Now im actually starting to understand more about how all these different wave antennas work. The coax cable thing sure did help though, before it was running horizontal straight off the antenna and was screwing with the tv and computer. The 1/4 seems to do great though, It was talking skip all day today with no complaints. I just dont know if it would be enough gain to make worthwhile. But I think ill just build another like you said. No use in ruining a perfectly functional antenna.

[drdx]

Great topic. Hey, check into J-poles too. They are of the same genre and employ 1/4 wave matching stubs (not complicated once you see one). Doesn't the antron use a quarter wave stub, or am I mistaken? -drdx

[nutcracker]

yeah drdx, ive been looking into all different antenna to experement with. But now im trying to figure out a power setup without spending 300 bucks! Anyway A couple days ago I had to climb up and adjust the driven element lenght because it was around 105'' so I had to lower it a inch or so, then I come inside and check my swr and its around 3 now. I feel pretty stupid but I left an aluminum ladder decently close to one of the radials which was lowering my swr causing a false reading. Just wondering, how do you adjust these antennas? Im assuming just lower and raise it? And would another radial help? I actually like this antenna quite a bit, just can seem to get it perfect yet.

['Doc]

Adjusting antennas.
Two ways, basically. You go to where it's at and make adjustments, or you bring the antenna where you are to make adjustments. Pick the one that's easiest for you to live with. Neither is going to be 'easy', just sort of 'easy-er', sort of.
"Perfect" is not attainable. 'Perfect' for you is 'sort' of attainable for very particular instances. Getting 'close' is reasonable and can be done fairly often.
Adding radials is a 'diminishing returns' sort of thingy. If you start with nothing, then any improvement is good. After some undefined point, adding more just isn't worth the effort. If you keep adding radials and always see an improvement, then it's very likely that there's a problem somewhere else. Just depends on how 'picky' you are, and how 'fine' a measurement you can take. When it get's to the point where it costs more than that 'improvement' is worth, you've gone too far so quit.

All of the above is a generalization, and as such, just depends on the person doing whatever it is they are doing. "If" and 'No" are the two shortest 'dirty' words I can think of.
- 'Doc

[nutcracker]

Your right doc I cant get it perfect or anywhere close. Id just like a good solid swr of 1.3 or so on 1-40. I wouldnt say I put too much effort into it, its just an on and off thing. I go out and mess with it when im bored and just stop when my hand starts to freeze to the aluminum. And its not on the pole anymore, its just outside above my roof a little bit, so climbing a few feet up isnt a problem. Im also starting to consider theres problems elsewhere, and I think that problem is that im overthinking it and just need to stop. So basically i think im done, its been fun experimenting and I have learned alot no doubt about it.

[19dt2120]

I found an other version of the J-pole , it's called de C-pole.
Also nice for the diy guys,but a bit more advanced.
I did not build it by my self,but gonna do it next summer.
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[nutcracker]

Alright, well I said I was done until today. After all doc, you mentioned about the coax having to run parellel with the mast. The bottom was horizontal into my shack. I got some longer LMR400 coax and rerouted it, and what do you know? 1.1 swr all through the band, even with the amp on! But my last question is about the radials. Right now the mast is up against the house, so theres 4 radials pointing north, west, and south. But not east because the house is in the way. Is this ok? Or should I find a way to move it out and away from the house? Which would have to wait being that the grounds frozen

['Doc]

147 express,
Cross polarization (vert/horiz) causes some loss of signal, quite a bit at times. Nothing new about that, been that way forever. That can be both a handicap and a benefit, just depends on how/what your purpose is. Also why there are some antennas with elements both vertical and horizontal, right?
As for them hearing you better than previously, beats me, just too many possibilities to make a guess at. Certainly possible though. The only absolutely positively bestest antenna around is mine. Why? Cuz I say so. And if you believe that, I got this boat for sale...
- 'Doc

['Doc]

nutcracker,
If it's working to your satisfaction, and if things seem to be right, then it sounds like it's doing okay. Would it be worth moving it further away from the house? 'Nuther one of them 'beats me' thingys. Maybe, and then maybe there wouldn't be enough difference to really tell any difference. I only know of one way to be sure, and I'll bet you can guess what that is. If you feel like it, why not try it? If you don't, then why bother? Unless there's something very unusual about how/where it's at now, don't expect miracles.
- 'Doc

[nutcracker]

The antenna is working fine, may move it out this spring once I get a couple hundred feet of coax. But for now its working excelent. Just curious though, on the site it said the driven element should be 104'', well mine has to be shortened to 95'' to get a good swr, wouldnt this make it less than a quarter wave? It dosent really matter just curious

[nutcracker]

Also, just an update, I found the high swr problem, it was that the center conductor and shield part that was stripped was running right up against the driven element, causing the super high swr. Also the conductor part is about 6'' longer than the braid, im assuming this would be the reason the element would need to be shortened to make up for the length of the braid and radials.

[Bozo]

This one might help or give you an idea


Here is a inexpensive vertical antenna..11 meters 27.113 <chnl 13> or make it for your favoite frequency for top notch transmitting and reception.

You need the following
2-10 foot lengths of 1/2 inch galvanized electrical conduit
2-stainless steel adjustable hose clamps
1- 5/8 inch wooden dowel

cut the conduit to the proper length..17. feet, 2 inches.
formula 468 divided by f in MHZ
cut the conduit to a length of 17ft 2 inches
the wooden dowel is placed in the middle of your conduit pieces, if it is to tight sand it a bit to make it slide in make sure it is a snug fit. leave a gap of one inch between the two pieces of conduit, plug the top conduit so water doesnt get in use caulking <liquid nail works good>.use the adjustable hose clamps one on each conduit pole close to the end closeto the wooden dowel, one end of your coax goes to one side and the other goes to the other side<example center conductor to one side, ground braid to the other> and tighten them with the hose clamp.
Your swr will be around 1.3 to 1 if higher you might want to cut a small bit off the pole about 1.5 inches no more.
If you want a flat swr run it into a antenna tuner....
You can mount it anywhere <antenna>, vertical just use a u bolt mount it on a pole with a flat small board behind it so not to have the conduit pole touch the pole you are mounting it on.
Drill a hole in the top and have it just hang down from a tree branch or whatever, use good coax also not RAT SHACK stuff.

Hope this helps

........ easy project to build a vertical for CB , I have configured it for chnl 13, but you the radio operator can configure it for your favorite channel or free band frequency...


DOCTOR/795

:D

[nutcracker]

Now just ONE more thing, Im almost positive this thing is only transmitting to the west now. I have made 0 contacts to the east or south, compared to 50-60 to the west. What exactly would be the cause of it being directional? And I am working on a new 5/8 antenna that will be up the full 40' once the ice melts.

['Doc]

It's just not very likely that a single vertical antenna is going to be very directional. If it' just happens to be the right distance away from something that can act as a reflector or director then sure, it can become directional. Is it mounted close to something like that?
And then, sometimes it just happens like that due to propagation. Or maybe no one in the other direction is on the air when you are? Or maybe the sun reflecting off of the antenna is blinding people to your presence? ... Wait, that's next month that that happens!
- 'Doc

[nutcracker]

Well today I got my 213 in finally and am going to hook it up tomorrow. But Today i welded a washer on the pole for a connector so nothing has to be splice and tested it with some old rg58 and it works good, but does the copper wire coming out of the so239 need the shield or can it just be bare copper wire?
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['Doc]

nutcracker,
I think just the plain old wire will be just fine. Using braid wouldn't be beneficial that I could see.
- 'Doc