10 meter vertical dipole

[wesm1957]

I have constructed a 10 meter vertical dipole antenna to use with the HTX-100 radio I just got. I have looked on a few sites that show others using a 1:1 air coil balun on their antennas. This is the antenna I have constructed : 10M Vertical Antenna by dxzone.com. My question is it needed? I have not gotten the antenna up and coax ran yet. I am planning on doing that Thursday as long as the pinched nerve in my arm will let me.

Thanks,
Wes

 

[LtDoc]

I'm not sure what you are asking. If it's if a vertical dipole will work, or work with your radio, then the answer is yes. If you are asking if a balun, as opposed to a 'choke' is necessary, then the answer in both cases is not absolutely. There's considerable difference between a balun and a choke, no idea which you mean. If that 'balun' (choke) amounts to several turns of coax in a coil then that isn't a balun in any way, it's a choke , and they can certainly be handy in some instances. A 'choke' chokes off stray/unwanted signals from the outside of a feed line which can cause problems. A balun only changes from an unbalanced feed line (coax) to a balanced radiator/antenna such as a dipole, which can cause some distortion in the radiation pattern. Either of those 'states' can cause unwanted 'crap' on the feed line that you would rather not contend with. Neither are mandatory or always a necessity. How do you tell it either are a necessity? Try it without that 'doo-dad' and see what happens. No particular 'bad' thing happens? Then don't bother.
You gotta do some thinking and trying before you'll ever know what I'm saying. So, doit how ever you want and see if it needs 'correcting', you know? Not only do you 'correct' some wrong, in some instances you even figure out why it happens!
- 'Doc

If you don't make mistakes then you never learn, and you'll nev er know why...

 

[zz0468]

"Needed"? It depends. Typically, on HF, you're not likely to notice any problem without the balun. Your antenna will just load up and radiate signals. What you won't be aware of is things like line radiation from the coax.

But sometimes that can be a problem, like RF in the shack, or a really screwed up antenna pattern if you're using a yagi. In which case, you use the balun to solve whatever particular specific problem. I've put up plenty of dipoles fed with coax and no balun. They worked just fine. I've had a few of them that caused RF in the shack or had excessive noise pickup. Baluns sometimes helped.

 

[zz0468]

...If you are asking if a balun, as opposed to a 'choke' is necessary, then the answer in both cases is not absolutely.

LOL... we posted at the same instant. At least our messages are consistent. Most threads don't do nearly so well!

 

[LtDoc]

You know, I was just thinking that we said dang near the same thing but just in a little bit different way. Hmm, amazing how like minds thing alike! And then again, that can really be more insulting than I intended, right? Oh well. I figure not using a balun is just one less 'point of failure' I have to contend with. The biggest difference is usually in the 'shape' of the radiation pattern, and since that can get really 'odd' from a number of reasons, how in the world can you correct that consistently?
There's always some 'variation' in the shape of a radiation pattern, doesn't matter if you are talking about a vertical antenna, a horizontal one. You 'learn' to compensate for that, especially with a directional antenna. Does that mean that you -might- miss something on the 'edge' of reception? Yep, but so what, that can happen with any antenna system. You can't 'correct' for everything, so do what you can and quit worrying about it!
Howz that for a compromise?? Or 'cop out', whatever you wanna call it?
- 'Doc

 

[wesm1957]

This is the balun I have started building: BUILD AN AIR WOUND 1:1 CHOKE BALUN FOR HF - THE UGLY BALUN! I will be able to put it in line if needed. Thanks for all the replies. I will have to try it both ways and see what the difference is. I will have to use a field strength meter to make sure I don't have any RF in the shack.

Thanks again!!!!
Wes

 

[K7MEM]

This is the balun I have started building: BUILD AN AIR WOUND 1:1 CHOKE BALUN FOR HF - THE UGLY BALUN! I will be able to put it in line if needed. Thanks for all the replies. I will have to try it both ways and see what the difference is. I will have to use a field strength meter to make sure I don't have any RF in the shack.

While that technically isn't a Balun, as others pointed out, the words Balun and Choke seem to be used interchangeably lately. Either way that is a good choice. Since you are already building it, I wouldn't wait and try to see a difference. I would just use it. I have a similar choke on my Hustler 5BTV and it works fine. Just make sure that the coil form is big enough. You need to keep the form large so that the coax is not deformed as it's wrapped around the form.

I also have a HTX-100 and a vertical dipole. Radio Shack use to make a vertical for CB that was billed as a "1/2 Wavelength Coaxial Antenna" for $39.95. It comes in two 9 foot sections that screw into each other. There is a base mount on the lower section which makes it convenient for strapping to a pole. Overall it is 18 feet tall. The coaxial feed goes through the center of the bottom element. Due to it's construction, it can't be modified and moved to 10 meters, but a small matching unit at the base will take care of that.

I'm not sure how long I have had the antenna (maybe 20 years) but the antenna seems to perform well. I use the HTX-100 mostly for CW and digital modes. For the digital modes I go in through the microphone connector with a home brew interface and I run the HTX-100 in the 5 Watt mode. It works great that way.

 

[LtDoc]

This really isn't 'nit-picking'...
That is a choke, not a balun in any sense of the word. It certainly can help remove unwanted RF/currents from the outside of the feed line, but it also certainly does not do any converting from a balanced to unbalanced state. It's a good idea to use the full/'accepted name' for it, an "ugly balun", or there can be a large gob of misunderstandings.
You can count on there being -some- RF in the shack. It isn't all that much of a problem until it starts 'biting' you or causes some other problem. So, just seeing the needle wiggle on a field strength meter isn't a 'bad' sign necessarily.
Good luck...
- 'Doc

 

[wesm1957]

Antenna and choke are up and connected. We had a heat wave here today, 40 degrees so I took advantage of the warmer temps and got everything connected. I either got lucky, or the old saying about putting an antenna up in bad weather makes it work better, but I have flat SWR. Thanks for all the help and advice!!!!!

Wes

 

[majoco]

I'd like to see a diagram of this 'vertical' dipole for 10metres and how the choke/balun is connected and how the feeder is run away from the centre. The diagram for the choke implies that it's for a horizontal dipole.

 

[wesm1957]

I'd like to see a diagram of this 'vertical' dipole for 10metres and how the choke/balun is connected and how the feeder is run away from the centre. The diagram for the choke implies that it's for a horizontal dipole.

The link to the construction of the choke has pictures of the choke connected to several vertical antennas. I will post some pictures of my setup tomorrow. I used 18 feet of 58x around a 4 inch pvc pipe. The outside diameter of the pipe is 4 1/2 inches. The connector at the antenna is a SO 239. I will find out in the morning how well the antenna works.

Wes

 

[majoco]

So it's not a dipole? Unless you count the invisible bit under the ground - it's a quarter wave or 5/8ths or something similar.

 

[wesm1957]

it is a dipole. there are no radials under ground. the shield side of the antenna (bottom) is 2 feet above the ground. Pictures will be posted friday

Wes

 

[wesm1957]

Here are 2 pictures of the antenna with the choke. I did make contact with Atlanta, GA this morning.

Wes

 

[k9rzz]

After 37 years of playing radio here's my take: no baluns on HF except perhaps a yagi or MAYBE if using open wire feeders and a tuner (depends on the tuner). Baluns on ALL VHF/UHF yagis otherwise the pattern gets skewed. After building and using numerous types of HF antennas, I've rarely had bad RF in the shack running <150 watts, but at 1kw+, then the game changes. =:^]

 

[wesm1957]

I think the antenna is doing a fantastic job. I made contact this morning on 25 watts with Berlin Germany

Wes