Balun a DiPole or not....

I get a lot of noise.

I have a DiPole and use an UglyBulan choke.
It is mounted a few meters over the roof tops.

I am surrounded with electrical interference as Im in the middle of a city, and cannot do anything bar move .
The interference is all over 10 and 11 meters, and is active only when my twig is outside the house [as a pose to indoors to test] [unless its raining or after 11PM ]

As a Dipole is a balanced aerial, a Bulan is not really nessacery, but would it help to filter out opposing interferences?

I Have spent much time scouring the internet for an answer, but it's a mixed bag of results, and usually people have a habit of not actually answering with a factual statement.

I expect it will be try one and see.........

Thanks in advance for your replies, and I value your opinions.
73's

Hi Andy. I am running technically a fan dipole. Adding a ferrite core wound balun did reduce noise for me. It is worth trying, as even if you buy one already constructed the cost is minimal, unless you want one to handle mega power.

Same here as Neal, (SangueG), with a multiband fan dipole in my loft space. 

Had a coax choke at first but knew it could be improved so added a typical ferrite balun which improved matters. Recently changed over to a 1:1 Common Mode Choke and the difference is absolutely dramatic with my noise floor dropping 2 - 3 S points! Loads more signals now coming through that would have been buried in the noise before. (The bathroom extractor used to wipe out my HF reception but now you'd never know if was on or not.  )

It's not all just about preventing RF coming back on the coax, common mode noise is a big issue too.


They're easy to make, have a Google for "HFKits" and you'll come across their Dutch site with details of CMC's and even how to wind your own. You don't need an expensive FT240 toroid if you're using lower powers, ( <150W ), and can get away with a cheaper FT140 toroid.

A Ham friend has seen the difference it made to my setup and is now incorporating one on his End-Fed antenna.


Best of luck with it all,
Victor

Thank you Victor for your wholesome reply.

I was looking at a FT240-31 Fair-Rite Toroid ring, until what you said about your 1:1 balun, so Ive seen a "Super Yagi 1:1 current balun high common mode choke wideband 400w"  <as ebay titled>  which might be the better to go for...[besides its all made up in a box]..going for it

NoMad wrote:

As a Dipole is a balanced aerial, a Bulan is not really nessacery, but would it help to filter out opposing interferences?

Well, a Dipole is balanced, but your coax isn't...hence, a BALUN (Being BALanced to UNbalanced) is exactly what is used, though not always required. 

However, don't confuse a balun used for this purpose from what is really a choke, to choke off common mode currents and noise...the terms seem to get used interchangeably. 

Either may help with noise, but equally may not...it really depends on the source of the noise.  However, they certainly won't hurt. 

31 material is better suited to low end HF, whereas 43 and 52 mix are generally better for higher HF bands.  Best reference I have found is that from G3TXQ, now sadly a silent key.

http://www.karinya.net/g3txq/chokes/

I have now installed my 1:1 balun in place of the uglybalun/airchoke.

There is minimal difference in signal, the noise level is exactly the same, but maybe some qrm pulsing/clicking sound has been reduced. Thats all. 

FM averages S4 and SSB averages S7 !  So I will struggle to hear anyone.
It's a shame. 



Any thoughts ?