Building CAT5 baluns

[Paul]

Since AV to cat5 baluns are so stupidly expensive, I've considered
building my own. I've seen a few ICs from analog devices that may be of some
use, but right now I'm just wondering if anyone here has tried building
their own baluns?

- Paul

[BruceR]

I know there are some at really high prices but I've had good luck with
some $15 ones from www.pimfg.com (click on Security and then Video
Baluns which takes you to
http://www.pimfg.com/local_cat_a.asp?main_type=107&master_desc=Security&sub_type=1&secondary_desc=Video+BalunAt that price I don't think there's much savings in rolling your own.Their catalog is filled with great stuff at very good prices and they'renice people to deal with.From:Paulwebster1@fuckspam.nizon.ca> Since AV to cat5 baluns are so stupidly expensive, I've considered> building my own. I've seen a few ICs from analog devices that may be> of some use, but right now I'm just wondering if anyone here has> tried building their own baluns?>> - Paul

[Mark Thomas]

BruceR wrote:
> I know there are some at really high prices but I've had good luck
with
> some $15 ones from www.pimfg.com

They don't seem to have any with audio. Know of a source for cheap
audio baluns?

[BruceR]

http://www.riowave.net/audiobalun1.html $25

From:Mark Thomas
mrt@thomaszone.com

> BruceR wrote:
>> I know there are some at really high prices but I've had good luck
>> with some $15 ones from www.pimfg.com
>
> They don't seem to have any with audio. Know of a source for cheap
> audio baluns?

[Andrew Burgess]

"Paul" <webster1@fuckspam.nizon.ca> writes:

> Since AV to cat5 baluns are so stupidly expensive,

Yes!

>I've considered
>building my own. I've seen a few ICs from analog devices that may be of some
>use, but right now I'm just wondering if anyone here has tried building
>their own baluns?

I don't think baluns use ICs since they don't require power. Baluns are
traditionally just transformers. I think they are a few windings around the
right ferrite core.

You are maybe thinking of using op amps with differential outputs? That would work
too and if you were building a circuit anyway thats probably the way to go.
I'm still designing my HA circuit boards but I'm pretty sure they'll have mic
inputs driving one of the wire pairs in a cat5 cable differentially, unless I make
them smart enough to do the audio A/D and send digital audio...

Good luck and let us know what you do.

[Si Ballenger]

On Mon, 14 Feb 2005 23:15:33 +0000 (UTC), Andrew Burgess
<aab@athlon.cichlid.com> wrote:

>"Paul" <webster1@fuckspam.nizon.ca> writes:
>
>> Since AV to cat5 baluns are so stupidly expensive,
>
>Yes!
>
>>I've considered
>>building my own. I've seen a few ICs from analog devices that may be of some
>>use, but right now I'm just wondering if anyone here has tried building
>>their own baluns?
>
>I don't think baluns use ICs since they don't require power. Baluns are
>traditionally just transformers. I think they are a few windings around the
>right ferrite core.

I looked into them and they seem to be toroidal transformers that
are wired straight through instead of like the usual ransformers.
I've often wondered if the cheap coax to cat5 baluns would work.

[Frank Mc Alinden]

Hi Guys

I have a pair of KAT5 Modules which can be used for audio and video....

As far as being cheap ...to some people if it costs money its expensive ..to me these units are priced quite reasonable...and very popular in the Uk..ha Community..

http://www.kat5.tv/

Frank

[Isaac Wingfield]

In article <1108421823.292597.60770@f14g2000cwb.googlegroups.c om>,
"Mark Thomas" <mrt@thomaszone.com> wrote:

> BruceR wrote:
> > I know there are some at really high prices but I've had good luck
> with
> > some $15 ones from www.pimfg.com
>
> They don't seem to have any with audio. Know of a source for cheap
> audio baluns?

"Balun" means "balanced to unbalanced" and the original definition
implies that some kind of impedance control is going on. You can find
baluns to go from 300 ohm twin lead (balanced) to 75 ohm coaxial cable
(unbalanced). The four-to-one impedance ratio is common (because it's
easy) but is by no means necessary.

Since there is no "characteristic impedance" associated with
transmission lines used for frequencies in the audio range, any
transformers that have the appropriate frequency response and voltage
ratio will work just fine. Put one at each end of the line.

Isaac

[John O]

>>I've considered
>>building my own. I've seen a few ICs from analog devices that may be of
>>some
>>use, but right now I'm just wondering if anyone here has tried building
>>their own baluns?
>
> I don't think baluns use ICs since they don't require power. Baluns are
> traditionally just transformers. I think they are a few windings around
> the
> right ferrite core.

At high frequencies a balun might be a turn or two around a core, the TV
baluns I've destroyed were like this. At audio freqs, it takes a lot more
turns. I believe the cost trade-off is bandwidth. If you want high-quality
audio, you need the better baluns. OTOH, A-Bus uses Cat5 straight up...no
baluns at all.

-John O

[Andrew Burgess]

Isaac Wingfield <isw@witzend.com> writes:

>"Balun" means "balanced to unbalanced" and the original definition
>implies that some kind of impedance control is going on. You can find
>baluns to go from 300 ohm twin lead (balanced) to 75 ohm coaxial cable
>(unbalanced). The four-to-one impedance ratio is common (because it's
>easy) but is by no means necessary.

>Since there is no "characteristic impedance" associated with
>transmission lines used for frequencies in the audio range, any
>transformers that have the appropriate frequency response and voltage
>ratio will work just fine. Put one at each end of the line.

It would be interesting to try the 75 to 300 ohm TV baluns for audio.
They are very very cheap...

[Andrew Burgess]

"John O" <johno@#no^spam&heathkit.com> writes:

>At high frequencies a balun might be a turn or two around a core, the TV
>baluns I've destroyed were like this. At audio freqs, it takes a lot more
>turns. I believe the cost trade-off is bandwidth. If you want high-quality
>audio, you need the better baluns. OTOH, A-Bus uses Cat5 straight up...no
>baluns at all.

It looks like A-bus requires power so I'd bet they are differential opamps.
http://www.home-technology-store.com/detail.aspx?ID=950

[John O]

> It looks like A-bus requires power so I'd bet they are differential
> opamps.
> http://www.home-technology-store.com/detail.aspx?ID=950
>

I played with one of these, and one pair is power, two pair are signals. The
signal line is unbalanced.

-John O

[Isaac Wingfield]

In article <cut92d$9fu$1@cichlid.com>,
Andrew Burgess <aab@athlon.cichlid.com> wrote:

> Isaac Wingfield <isw@witzend.com> writes:
>
> >"Balun" means "balanced to unbalanced" and the original definition
> >implies that some kind of impedance control is going on. You can find
> >baluns to go from 300 ohm twin lead (balanced) to 75 ohm coaxial cable
> >(unbalanced). The four-to-one impedance ratio is common (because it's
> >easy) but is by no means necessary.
>
> >Since there is no "characteristic impedance" associated with
> >transmission lines used for frequencies in the audio range, any
> >transformers that have the appropriate frequency response and voltage
> >ratio will work just fine. Put one at each end of the line.
>
> It would be interesting to try the 75 to 300 ohm TV baluns for audio.
> They are very very cheap...

I think it's very unlikely that they would function well at audio
frequencies. Not enough iron, and nowhere near enough turns.

Isaac