Conduit dipole swr issues

[W5LZ]

Just for grins, try it the other way around. Instead of sticking something inside that conduit, try sticking that conduit into something. As in a chunk of wood maybe 3" x 3" and long enough to provide a surface to mount the thing with. Bottom conduit won't stay in that block? Use a screw/bolt through the block and conduit to hold it in (also provides a nice place to make electrical contact). Do the same thing for the top conduit, what'tha'heck? Or, substitute plastic/fiberglass/ceramic/whatever for 'wood'. All kinds of options there. Sort'a the same thing commercial builders do with antennas, just not as 'sophisticated'?
- 'Doc

 

[ron103067]

Just for grins, try it the other way around. Instead of sticking something inside that conduit, try sticking that conduit into something. As in a chunk of wood maybe 3" x 3" and long enough to provide a surface to mount the thing with. Bottom conduit won't stay in that block? Use a screw/bolt through the block and conduit to hold it in (also provides a nice place to make electrical contact). Do the same thing for the top conduit, what'tha'heck? Or, substitute plastic/fiberglass/ceramic/whatever for 'wood'. All kinds of options there. Sort'a the same thing commercial builders do with antennas, just not as 'sophisticated'?
- 'Doc

thanks doc i was thinking about using a piece of pvc pipe with all thread inside didnt know if that would be wise wasn't sure if it would react with the signal

 

[W5LZ]

Most times PVC will work just fine as an insulator. There IS a catch though. Some types of PVC are not a very good insulator at all, they have some metallic content. Wish I could remember which is which, but it's early, not enough coffee, and all them other excuses. From my experience, the white kind works okay. Which doesn't really tell you anything. Sorry 'bout that.
- 'Doc

Ain't this S_ _ _ fun?!

 

[ron103067]

Most times PVC will work just fine as an insulator. There IS a catch though. Some types of PVC are not a very good insulator at all, they have some metallic content. Wish I could remember which is which, but it's early, not enough coffee, and all them other excuses. From my experience, the white kind works okay. Which doesn't really tell you anything. Sorry 'bout that.
- 'Doc

Ain't this S_ _ _ fun?!

I'm loving all this. It is a whole lot of fun. It felt really good when I was listening to skip the other day on my home made antenna. I like building this kind of stuff. The one thing I asked that no one seemed to answer is is there a better material I can build this antenna out of like copper or alunimum.

 

[W5LZ]

Copper/aluminum? Not enough difference to make any practical difference at all. Biggest differences are weight and being able to solder to it. If you can solder to it, aluminum cans make for a fairly nice 'beverage' antenna! Brand does make a difference. 'Miller Lite' cans do better than 'Budweiser' cans... 'Sadder Bud-Wiser' you know. Besides, Miller Lyte doesn't weigh as much, says so right on the can, don't it?
- 'Doc

 

[ron103067]

Well I was just wondering if copper or alunimum would be better than conduit. or is it just the weight issue

 

[Robb]

Copper may be easier to get from your local hardware store than aluminum would. If you are going to use wire and PVC pipe, you may want to get the type that is approved for UV exposure. It cost a bit more - but not a lot more. PVC that doesn't have UV protection will degrade and break apart in less than a year or two. Making your project disintegrate. It is just a consideration to remember.

 

[C2]

When I made my 2m 5/8 wave antenna, I used that grey PVC "nipple" that is threaded on both ends. Hope it works out.

 

[Beetle]

Aluminum tubing is the better way to go...you don't see commercial antennas made of copper tubing, because it's far less strong, size for size.

As far as soldering to it, fuhgeddaboudit, as they say. Use stainless steel hose clamps of the appropriate size; don't allow copper to come into direct contact with the aluminum, however. That could be less than a good thing. Or, use crimped and soldered ring terminals, with stainless screws, lockwashers and nuts. Don't use self-tapping screws - they have a tendency to disassemble on their own.

 

[ron103067]

Well the next antenna I'm going to make is a pvc pipe antenna (dipole) and try that

 

[HomerBB]

All interesting reading.

I am in the same situation, but out of necessity. I have suddenly found myself without an antenna due to the ice storm. I am considering mounting the dipole at a 45 degree angle about 25 feet off the ground, but only about five feet above the roof line.
What, in the opinion of all, are my chances of success in this configuration?

 

[ron103067]

I've never tried it that way the thing I know is that horizontal the aren't much good for local use but having it angled should help the local and dx from what i hear

 

[Robb]

I'm going to use a female double-end S0-239 and use 110v zip cord and a piece of old coax and get the measurements right by using junk first.
Then I will replace each part with good stuff until it all works without any real problems.
Easier said than done, but that is why I'm going to make mistakes with junk first.
The distance between the conductors as it leaves the coax, the length of the wire used, the height above ground where I place it.
And -oh yeah- how the SWR will change when all of this is being done.
Because it is a half-wave dipole, it doesn't need a ground.
Making mental notes or even writing them down.
Also the changes that happen when I change it into an inverted 'v' dipole.
Another consideration will be the common mode current problem - if there is one.
And if so, coiling up some of the coax close to where the coax enters the 'T' fitting.
Or, if it will need a balun iof the resistance is too high.
That is a s far as I can see ahead of time those things that will be needing attention. As far as I know now - anyway.
It is a learning experience with the possibillity of gaining an antenna if I get it right...

 

[74IN]

Would a coat of spray paint help slow the UV drying out the pvc?

 

[Robb]

Oooh; tough question...
PVC has a surface that may require a special kind of paint to adhere to its surface.
Sure; why not? If nothing else it should slow down the process even if it isn't the right kind of paint.
By that time, you can build a new one with the better tubing. Maybe even better,