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High power 1.1 balun for quad

-=PEAKABOO=-

-=PEAKABOO=-

Active Member
Oct 29, 2001
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Just curious if anyone has any experience with building a home brew 1.1 balun for a quad that can handle higher power, say 10KW. I know you can buy them and I have built smaller ones for various antennas. I would rather build this one as well. I am planning on building a 4 element quad for 10/11 meters and want to be able over build the balun. I have build them with a 2.4" outer diameter type 43 ferrite donut but never ran much power through them. I do not want to find out the hard way that I built it to small:D.
If anyone has any experience or suggestions with this subject I would love to hear it.

Thanks
 

I have'nt used a balun that large, but what about using a gama and voltage feed the quad.

The only antenna I use a balun on is a 160 meter loop, and thats just for multi band operation.

Maby someone else will chime in .
 
Personally I would use an air core balun for that much power. It will have less loss and there is no iron core to saturate and cause heating and spurious emissions and the resultant interference.
 
I'm guessing if the power level is for 10KW, he's going to use either some really large coax or possibly heliax? That means the choke balun is probably out of the question. I know there is a way to wind an air core balun with stranded wire...but I've never seen it done. Any suggestions on how to do this?
 
PEAKABOO,
I'm afraid 'Captain Kilowatt's idea is really about as 'close' as you're going to get with that much power. I haven't looked to see what's being offered in baluns in the commercial areas in a long time, but 10 Kw is sort of pushing it a bit. That'd be one large balun! I imagine the cores would weigh almost as much as that quad. Sure, that's just a bit of an exaggeration, but not much really. I also seriously doubt if 'they' could just go pull it off the shelf, it'd be custom made (even if you wound it, the cores would not be the typical 4" 'donut' cores from the stock bin).
I can see a lot of problems with a quad handling that much power. Don't misunderstand, I'd love to have a quad, but getting around the problems associated with one that size would be a lot of 'fun'. And would it be worth it? Beats me.
Good luck.
- 'Doc
 
I just remembered that I saw some high-powered ones at Dayton last year. Here are some pics of a 10KW balun by M2:



moleculo-albums-2009-dayton-hamvention-pics-picture815-msquared-1-1-10kw-balun-inside.jpg
 
moleculo said:
I just remembered that I saw some high-powered ones at Dayton last year. Here are some pics of a 10KW balun by M2:



moleculo-albums-2009-dayton-hamvention-pics-picture815-msquared-1-1-10kw-balun-inside.jpg
Click to expand...

See, that is more like what I am wanting to do. The last large balun I made about 5 years ago was for a rhombic antenna we were experimenting with. Me and a friend strug the antenna from trees and parked my truck right under the feed point. I was running quite a bit of power which made ferrite rain down on the cab of truck:D
 
Henry HPSD said:
Guys,

What about a sleeve or pawsey stub?
Just a pipe 1/4 wave length long.
Fits exactly around the coax.
(You could make one using a female female connector.)

73 Henry
19SD348
Click to expand...

Logistically, how would one add that to LMR-400 far enough down so it is out from inside the beam if the point of coax attachment is at the boom?

One wavelength down and strip away the casing to attach?

Does it require insulation from the coax / casing so it does not arc through the casing at high power?
 
Hello,

I am sorry but i dont understand your question (american is not my native language from the european continent here..).

If i am not mistaking you are worried on because of the length?..
When i google LMR400 i see coax that can bend so you could make a circle of it..and use a pawsey stub. (just add a 1/4 wave length long piece of LMR400) would be approx..1,8 meters long. That is about the same length as a leg on quad would be..

For verticals or normal yagis you could use the metal tube...cause it will be along the boom/mast..

Futher i would recommend to measure the velocity factor (i had a couple times it was not what the manufacturer mentioned.

Hopefully i answered your question if not ..try putting it in a different way or perhaps some other who does understand can help you out ?

Henry
19SD348
 
Yes, it can work....but.....You can have "currents" running over your coax cable these will cause problems (TVI etc).

Its like doing "things" without protection you can be lucky..
but if things are wrong you will end up with big problems

73 Henry
 

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