The "Ugly Balun"

[packrat]

packrat,
a choke balun is not to stop stray rf from getting back into the shack, it is to stop the equal currents that flow inside the coax from been split between the radials and the coaxial outer shield,
cm current flowing on the coax outer shield or mast is current lost from the radials,
rob has the right idea on his imax with short radials, we have done the same thing and seen an improvement in signal and a big reduction in rf on the feedline even though the choke i wound had twice the coax we should have used.

HUH???

 

[bob85]

read the links i posted,

A choke / balun has nothing to do with swr or signal. All an ugly balun sic (choke)will do is help keep stray rfi from getting back into your station on the coax shield.
You also dont need one unless you are experiencing rf in the shack.
It wont do a thing for your neighbors.
PR

 

[Marconi]

Bob says the following:

packrat,
a choke balun is not to stop stray rf from getting back into the shack, it is to stop the equal currents that flow inside the coax from been split between the radials and the coaxial outer shield,
cm current flowing on the coax outer shield or mast is current lost from the radials,
rob has the right idea on his imax with short radials, we have done the same thing and seen an improvement in signal and a big reduction in rf on the feed line even though the choke i wound had twice the coax we should have used.

And packrat says:

HUH???

Hey packrat if you just want to stop RF coming from your feed line and getting into the shack, try laying as much of your feed line a/p directly on the ground, from the base of the mount to the shack. If you can do this with about 20' feet or more, you may find the earth absorbs most of the CM currents that maybe causing the problem. If you have a hot radio chassis instead, that could be a different problem that might be related to the ground at the radio setup.


If however, you have enough coax to form a functional choke at the end of your feed line, and then attached it directly to the feed point instead, your efforts may provide a bit more RF current into the antenna---where it belongs, just like Bob85 suggested.

Your results may differ, but IMO this is the way to help your problem instead of just saying HUH???

 

[Lazybones1222]

huh??? Dah Gum It, I never understand a word Marconi says.

 

[BammBamm]

I'm still wondering......On a 5/8 maco gp mounted to the eve and mounted to wood (no metel mast) would a balun help or be needed? I have the extra coax and form and thought it might be good to make a balun at the antenna. If it would even remotely help I think I'm going to do it. I currently have about 3 s units of static on any channel any time of day on a 257hp with 50' of lmr400. I would be using 213 to make the balun.

 

[Robb]

I'm still wondering......On a 5/8 maco gp mounted to the eve and mounted to wood (no metel mast) would a balun help or be needed? I have the extra coax and form and thought it might be good to make a balun at the antenna. If it would even remotely help I think I'm going to do it. I currently have about 3 s units of static on any channel any time of day on a 257hp with 50' of lmr400. I would be using 213 to make the balun.

Doubt that it would hurt to do it. Since there is no steel mast to catch any CMC being generated, if there is any present it will probably be found on the coax. So it might be wise to do so. Not going to change the noise much though; that is from another cause since most of the noise experienced is from man-made sources.

 

[vkrules]

Ok most things have been covered by previous posts. I would like to ad that the choke can change your swr if you have a bad cmc problem as well as lower the noise level in some cases.If you have the cable fit the choke it won't hurt , if it changes the swr significantly it is only because it has fixed the problem. Other tell tail signs of cmc on the cable are if you touch the coax or pl259 or give the coax a swing and the noise changes on rx or swr changes on tx. In extreme cases the radio will bite you and or the hair on the back of your neck will stand on end. On another note lately Iv'e been using the SIRO choke for 27 and 28 mhz . 16 turns on a 65 mm former and found it the best iv'e tried.

 

[BammBamm]

Thanks. I have found this evening that if I turn off my attic exhaust fan in my home that my static noise goes down to no reading on my digital meter in radio. I'm thinking one of my ground radials must run right over it on the roof or it is at the peak of the roof right at the end my antenna is on. The peak of my roof is about 35-40 foot and is my only current mounting spot and is a little scary trying to hold a ladder and antenna and tools. I'm trying to get approval for a 50' tower and if I do it will be on the side away from the attic fan. I know many would say just turn off the fan but with a black shingle roof and little to no shade above the house that fan makes a huge difference on my AC bill. I think I'm going to put a balun on it anyway.....it can't hurt. By the way last night I plugged in my Beats by Dre ear buds and found I can hear myself in my head phones but I don't affect any electronics in my home or any of my local neighbors (yes I did ask all of them in a 2-3 house radius of my home and told them if they find ANY issues to inform me so I can correct it.)

 

[Dolomite]

I would suggest you go back and read the very first paragraph of that article again. That Coaxial 'choke' is not a balun. You can call your cat a dog, but I wouldn't quit buying cat food till you hear it barking, you know?
- 'Doc

LOL!