diy 1-1 unun

[p.larner]

i have a 43 mix binocular core,i want to make a 1-1 unun using that and some rg-174 coax,how can i make it,wind etc,thanks in advance.

[A.Z.]

are you asking about a 1:1 BalUn/Choke or what ?

if so, just follow this by the letter

https://www.dj0ip.de/rf-cmc-chokes/different-kinds-of-chokes/d2-guanella-choke/

[p.larner]

Hi,its for connecting my 300 ohm antenna feeder to the input of an atu-100 atu so i assume its a 1-1 unun i need,i have an ft-240-43 core but  no room in the case for that,but the binocular core would fit,i just am not 100% sure on the winding details ok 73.

[A.Z.]

Hi,its for connecting my 300 ohm antenna feeder to the input of an atu-100 atu so i assume its a 1-1 unun i need,i have an ft-240-43 core but  no room in the case for that,but the binocular core would fit,i just am not 100% sure on the winding details ok 73.

Ok, so follow the directions at the link I posted, connect the BalUn to the ATU using some coax (leave it outside the ATU) and connect the other end to the two conductors of your balanced line, all the infos you need are at the link, just focus on it and read carefully

[vk4ffab]

i have a 43 mix binocular core,i want to make a 1-1 unun using that and some rg-174 coax,how can i make it,wind etc,thanks in advance.

Wind the coax in one hole, out the other, over and over again. Nothing difficult here, a single winding on a binocular core is in one hole out the other in a U shape. If you can get 2 or 3 windings on that core you are good to go. Connector on one end to the transmatch, solder the other end direct to the open line feeder. BOOM, DONE! Probably better to do that on a larger single core or to use 1mm enameled wire on the binocular core. The largest binocular core I have is good to 100w, but the holes are not big enough for enough windings using 174 coax to get decent choking.

[p.larner]

az cheers for the link but theres no mention of any ununs wound on a binocularcore tho,they are torroid rings not binocular cores.

[Andy Chee]

This is one winding on a binocular core:



I don't know how many turns of RG-174 you'll be able to fit, but if you can, use the same number of turns as if you were winding a toroid.  Otherwise just fit as many as you can.

The input and output terminations will be exactly the same as a toroid.

[A.Z.]

theres no mention of any ununs wound on a binocularcore

First, you will need a BalUn (from BALanced-UNbalanced) since you're connecting a BALanced line to an UNbalanced one (your ATU), then, as for the binocular core, which type/material is it ? Or, if you don't know that, what's the size of that core ? Because, see, aside from some pretty large binocular cores, most of them don't have enough room for the needed windings, that's why people prefers using toroidal cores, and since you wrote you have an FT240-43, I think you'd better consider using it and placing the unit outside your ATU and not inside it and there are some reasons to place it there

https://www.dj0ip.de/balun-stuff/tuner-baluns/

also see

https://www.dj0ip.de/balun-stuff/tuner-baluns/d-i-y-tuner-balun/

[A.Z.]

ok ... as usual, didn't expect anything else

[p.larner]

the point of using a binocular core was down to room,its to fit inside an at-100 kit,there is not room for a torroid,this is why i asked the question in the first place ok.

[A.Z.]

ok, despite what was written, you WANT to use a SMALL binocular core, go on, do it and when you'll discover it doesn't work as expected and it cannot support your TX power come back and open another discussion ... as usual

[vk4ffab]

the point of using a binocular core was down to room,its to fit inside an at-100 kit,there is not room for a torroid,this is why i asked the question in the first place ok.

OK, we have been giving you bad information from a lack of information. You do not want to wind this as a current balun IE a common mode choke, you do not want your little binocular acting as a choke it does not have the mass to dissipate the heat. Rather you want to wind this as a voltage balun. The smaller binocular should be fine to 100w would this way. Using 0.5mm wire minimum, you want 5T primary and 5T secondary and that will make the single ended output of the tuner, differential for the open wire feed antenna.

[p.larner]

Ok i have had a rethink on this,i will use a ft-43 torroid,is it ok to have it mounted in an eddystone type cast aluminium box?.or will the metal box affect it?.

[A.Z.]

no metal box, it will affect the currents flowing over the braid use a "plastic" box, a simple electrical junction box will fit

[A.Z.]

As for the 1:1 BalUn/Choke, follow the directions here

https://www.dj0ip.de/balun-stuff/tuner-baluns/d-i-y-tuner-balun/

and you won't be wrong, place it into a plastic box, put a panel connector at one side and two binding posts at the other and you'll have it, using an FT240-43 toRoid (ONE "R" not TWO) it will serve you well from 80 to 10 meters and will also work on 160; notice that the "favors..." annotations at the above page mean that on the reported bands the CM impedance will be higher so the unit will be more efficient, but it will also work on the other bands, the idea is to "favor" the bands where your antenna tuning is "critical"; in general my choice is to wind 17 turns on an FT240-43, the above links also contains detailed instructions showing how to properly wind the toroid

[p.larner]

can i use side by side speaker wire and wind it the same as the pic?, Or is rg-58 a must ?.

[p.larner]

also can this be mounted in a metal box if the two binding posts for the ladder line and the outer of the so-259 are insulated from the box?.

[A.Z.]

reread the link and my previous post, do not screw things.

[p.larner]

Then please explaine how that answers my question on does rg-58 have to be used, Or are you just trolling??.

[A.Z.]

the type of coax is clearly stated at the link I already posted, just a matter of reading with a bit of ATTENTION, no trolling aside from YOURS

[vk4ffab]

can i use side by side speaker wire and wind it the same as the pic?, Or is rg-58 a must ?.

A transmission line is a transmission line yeah? None of my baluns are wound using coax. They are all wound using teflon sleeved enameled copper wire. Using speaker wire, as long as its of a suitable gauge for the power handling is perfectly fine. Its also easier to deal with when it comes to soldering on lugs for connecting to binding posts.

[p.larner]

thanks for a sensible answer from the vk4, is it ok mounted in a metal case as long as the banana posts for the ladderline are insulated from the box, Also can i wind it the same as in the pic i posted, Same number of turns etc?.

[A.Z.]

no, putting it inside metal box means that you did not understand how and why it works, fine, go on and blame yourself

[vk4ffab]

thanks for a sensible answer from the vk4, is it ok mounted in a metal case as long as the banana posts for the ladderline are insulated from the box, Also can i wind it the same as in the pic i posted, Same number of turns etc?.

I do not have a suitable answer to that. My gut says it depends. I mean, think of an antenna tuner, the old school balanced ones, big air caps, big roller inductor, big balun all sitting in a metal box. They do not seem to have a proximity problem, will a metal can effect a big toroid? I do not know, maybe, but I honestly think it wont make a difference, ferrite is not overly conductive, being in proximity to other metal probably wont have much of an effect on a 1:1 balun at all, 4:1 and other combinations it might have a slight de-tuning effect.

I do not have any good reference books here to lookup to get a better answer than that, but the last thing you want is for that metal can to become an antenna and start radiating, so for that reason along, i put things like baluns and my remote tuner into plastic. I hate antenna debates because there is a lot of voodoo out there and fan boys ranting and raving about stuff that has no basis in reality.

Long answer where answered nothing, other than to say, I would go with plastic out of precaution, but seeing tuners have metal cases and baluns in them, its probably not a problem. Try it and see what is what. The internals should be floating anyway and the case not part of the transmission line.

Yes wind and build as per your image.

[p.larner]

Thanks for your answer, I will try it in both a metal box ten a plastic one and compair, its just i have some eddystone type boxes but few plastic 73.