Ugly Balun - has anyone tried one

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Dragonfly
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Ugly Balun - has anyone tried one

Post by Dragonfly » 22 Nov 2010, 18:40

I recently purchased a sirio balcony w27 antena but have trouble getting it to SWR when put up high on my tv aeral mast ,
Has any one tried one of these home made RF choke on there antena.

Ive just made this one,need PL plugs now
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This choke apparently stops RF from emiting back down the outer coax and so concentrates all RF at the Antenna,Keeping the antena in better tune and improves signal strength ,or that is the idea.
Image

Sirios new gainmaster appears to have a Ugly Balun built in - http://www.gain-master.it/

Link to Ugly Balun - http://www.hamuniverse.com/balun.html

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Re: Ugly Balun - has anyone tried one

Post by Adriano9966 » 22 Nov 2010, 20:00

:) 7 views but not a single reply

in a word yes having an rf choke balun is a very good idea

I use one on my antron when im in france a home brew 70cms/2metre dipole and also on my hf4b which will be going in the air shortly moreover once I have the gable end of the house re-pointed I will put a vertical on there equipted with a choke balun as well basically as you already know this confines currents to the antenna so that its feeder does not become a part of the radiating system

I rather suspect though that the reason for the high swr is the metal mounting pole which possibly detunes the antenna :|

anyway the choke balun will still improve things in my opinion and is a good idea anyway

how come such a small antenna??????


hope this helps

kind regards Adrian :D

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Re: Ugly Balun - has anyone tried one

Post by Dragonfly » 22 Nov 2010, 20:21

Ive had all the big Antenna,s up before Sirio 2016 - Antron 99, 18ft GP was my last big antenna but just sold that recently as im about to move house into a bungalow ,Council around here want planning permision for big antennas now so im experimenting with a small antenna at the moment but if it comes up to short range then ill put a new GP up. or a wire dipole , this Ugly Balon aparrently helps high mounted Wire dipoles with there Radiation pattern and SWR so i may try it with that next.

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Re: Ugly Balun - has anyone tried one

Post by northern35s » 22 Nov 2010, 21:00

There's something wrong with your transmission line / antenna / mount if you can't get the VSWR within usable limits, I'd be surprised if a scramble wound choke would cure this, identify the problem first, connectors, antenna build, and connectors again, remake them if necessary, is the coax new, has it been crushed etc. I wouldn't have thought your antenna would suffer CMCs.
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Re: Ugly Balun - has anyone tried one

Post by northern35s » 22 Nov 2010, 21:04

Just seen a pic of the antenna, hmmm, not much of a ground network :o
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Re: Ugly Balun - has anyone tried one

Post by Dragonfly » 22 Nov 2010, 21:10

The Antenna has great SWR when its on the floor almost 1:1 ,same when i place it on my sons drum kit cymble stand .I think its ment to be clamped to brick but im trying to get it so it will work higher ,IE up on the TV mast.
I have a piece of wood between mast and antena at the moment so its not grounded to the pole.

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Re: Ugly Balun - has anyone tried one

Post by northern35s » 22 Nov 2010, 21:22

The pole shouldn't be required to ground it, have you checked everything, maybe not to easy if it's on the chimney.
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Re: Ugly Balun - has anyone tried one

Post by HomerBB » 23 Nov 2010, 00:01

I can't tell by the only partial photo I found what this antenna looks like, but seems to be a dipole, perhaps a loaded one to reduce size - just guessing.
I agree that a good looking over of all the components may be the best first step. After that is done add your coax choke (ugly balun). It never hurts, and always helps. an exception may be where the coax is itself a part of the radiating antenna, as in no-GP type antennas. Your assessment of the worth of the Ugly Balun is correct. I always use one, and its use has always required me o tune the antenna properly by isolating it from the coax.
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Re: Ugly Balun - has anyone tried one

Post by pioneer » 23 Nov 2010, 07:01

Yes ive tried them over the years, got one on my 80 mtr inverted 'L' antenna.

Just to say though, there not a BALUN there actually a 'RF CHOKE'..

A balun as the name balun 'balance-unbalance' is generally for using coax to a balanced antenna, such as a dipole, other baluns such as a 4 to 1 can be used for impedance matching.

the ugly balun 'rf choke' helps stop or reduce unwanted currents from travelling back down the outside of the coax braid.

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Last edited by pioneer on 26 Nov 2010, 18:38, edited 1 time in total.

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Re: Ugly Balun - has anyone tried one

Post by bigpimp347 » 23 Nov 2010, 19:43

just a quick one..
on some sirio boomerangs and others they are crap made, check where the coax socket SO239 connects to the aerial, i've seen a boomerang have a tiny wire for the radiator break here and also get full of water..

as for a balun, only ever use a 8 turn choke on my main aerial as i always have done, never seen any point, but everyone has their own opinion..
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Re: Ugly Balun - has anyone tried one

Post by wind in the antenna » 24 Nov 2010, 01:17

It's not actually necessary to coil the coax on a former. If you want it really 'ugly' you can just loop up any slack you have in your coax and cable tie it together.

A clip on ferrite slug has a similar effect and may be more appropriate in some circumstances.

Either approach never hurts but it's true what Northern says that if your antenna represents a perfect match then you should never need an RF choke to prevent current flowing back on the outside of the braid of your coax.

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Re: Ugly Balun - has anyone tried one

Post by pioneer » 26 Nov 2010, 18:42

No match is PERFECT, all antennas are affected (coupling) by there surroundings and all interact with them to some extent, the perfect antenna or match doesnt exisit.


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Re: Ugly Balun - has anyone tried one

Post by wa10 » 26 Nov 2010, 22:46

the vswr/match at the antenna is not what causes cm currents on your coax,
you will always have as much current flowing on the outside of the coax/mast as flows in the antenna on any no radial enfed antenna even one with 1:1 vswr, groundplane antennas with 1/4wave radials can also have mast/feedline currents with certain length masts/feedlines,

heres some good info if you want to understand antennas, what that common mode current is and where it comes from,
http://www.w8ji.com/end-fed_vertical.htm

an ideal ugly balun for 27mhz is 5 turns solenoid wound ( side by side ) of rg213 size coax on a 4-4.5" former or a little less if using thinner coax like rg58, the hamuniverse ugly is better than nothing but it won't provide a high choking impedance @27mhz,


good luck with your choking ;)

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Re: Ugly Balun - has anyone tried one

Post by wind in the antenna » 27 Nov 2010, 00:15

wa10 wrote:the vswr/match at the antenna is not what causes cm currents on your coax
Common mode current effects in an unbalanced feeder?
wa10 wrote:you will always have as much current flowing on the outside of the coax/mast as flows in the antenna on any no radial enfed antenna even one with 1:1 vswr, groundplane antennas with 1/4wave radials can also have mast/feedline currents with certain length masts/feedlines,
I'm not convinced. If a load acts as an ideal 50 ohm match surely current will flow where it is meant to and nowhere else. Current should flow on the inner conductor obviously, but also on the inside of the coaxial braid. It only flows on the outside when the load caused an incorrect termination. I can't see where radials come into this.
wa10 wrote: heres some good info if you want to understand antennas, what that common mode current is and where it comes from,
http://www.w8ji.com/end-fed_vertical.htm
I'm afraid that's one of the least compelling things I've read in years and certainly does not endorse your point
How much gain does a centre-fed halfwave dipole have according to this article?
wa10 wrote: an ideal ugly balun for 27mhz is 5 turns solenoid wound ( side by side ) of rg213 size coax on a 4-4.5" former or a little less if using thinner coax like rg58, the hamuniverse ugly is better than nothing but it won't provide a high choking impedance @27mhz,
It's not really a balun as such, it's an RF choke and the more Henrys it introduces to prevent the flow of stray currents the better. I don't know where 5 turns over a carefully measured former comes from. Obviously you'll need less inductance for higher frequencies but at what point would you have too much inductance?

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Re: Ugly Balun - has anyone tried one

Post by wa10 » 27 Nov 2010, 04:12

"Common mode current effects in an unbalanced feeder?"
yes it can, currents on the coax centre and currents flowing on the inside of the braid are ballanced, the coax outer braid is the third conductor that can carry cm currents,
maybe if they called them stolen or wasted current people would understand where it comes from more easilly,
"I'm not convinced. If a load acts as an ideal 50 ohm match surely current will flow where it is meant to and nowhere else. Current should flow on the inner conductor obviously, but also on the inside of the coaxial braid. It only flows on the outside when the load caused an incorrect termination. I can't see where radials come into this."
thats not how it works, cm currents can flow regardless of the 50ohm match at the feedpoint, the outer shield or mast can carry cm currents whenever their commonmode impedance is not very high or theres no other path for it to take ( radials or mast ),
a no radial endfed is only half of an antenna, cm currents must flow for the antenna to work, 50ohm termination will not cure it,
radials or some other return path has EVERYTHING to do with this topic,
"I'm afraid that's one of the least compelling things I've read in years and certainly does not endorse your point
How much gain does a centre-fed halfwave dipole have according to this article?"
i don't know what you have been reading for years but if you want to understand radio id find a different source of information,
you won't find anything that backs up anything you have said so far from any respected source,
alternatively build yourself a simple rf current probe and do some actual measuring,

how much gain a horizontal dipole has depends how high it is above ground, i know what your thinking 2.15dbi, not so, a horizontal dipole about 1/2wave above ground has more gain than any cb vertical,
if your not convinced id read up on the subject from people like w8ji, lb.cebik, walt maxwell and stay away from places like hamuniverse or ultimate 11mtr cb ect,
some topics on there are written by people who don't have a clue what they are talking about and it spreads like clap on cb and some hammy forums,
"it's not really a balun as such, it's an RF choke and the more Henrys it introduces to prevent the flow of stray currents the better. I don't know where 5 turns over a carefully measured former comes from. Obviously you'll need less inductance for higher frequencies but at what point would you have too much inductance?"
yes they do act like a balun, thats another hamuniverse snippet of nonesense,
since we are not dealing with tesla's zeropoint energy kirchhof's law works fine and dandy in this situation,
its not stray rf, its current that should be flowing in the radials,
the ugly forces current to flow where it should rather than allow current that should flow in the radials to be diverted down the feedline outer braid by inserting a high series impedance in the common mode path,
done correctly the ugly can give a higher choking impedance and power rating than most bought baluns, done incorrectly ( very common ) they are almost useless,

you can have too much inductance/turns and most people on 27mhz do including me before i wised up a little,
the why's are explained in several technical articles around the web and noted in the arrl antenna book series, also posted on this forum,
5 turns of 213 or a little less comes from actual measurements with hp vector network analysers ;)

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