Why Enameled Wire for 9:1 Balun?

[chrissim]

I had great success building my first antenna: a Windom. I'd next like to build a 9:1 balun for a long wire for portable receiving in the back yard away from the house (it would connect to a Lowe HF 150 - not a portable in the traditional sense).

All references I read report that one should use 18 AWG enameled copper wire. Is there some special property to enameled that requires it to be used? Should there be some type of medium between the wire wound around the toroid? Just not sure I get the enameled part.

Suggestions are appreciated.

 

[chrissim]

I'll attempt to answer part of my own question: apparently it has something to do with voltage insulation. Though this isn't for transmitting, only for receiving, so it shouldn't matter?

 

[SCPD]

It's not just about voltage but about the longevity of the wire. Copper wire will rust over a short time and thus its performance degrades.

Use enameled wire for your balun project. It's not very expensive:

315-Ft. Magnet Wire Set : Wire Sets | RadioShack.com

Sorry just noticed that you needed 18 AWG:

http://www.ebay.com/itm/Magnet-Wire...ding-and-Crafts-200C-/181063924268#vi-content

You could probably use 22 AWG just fine...

 

[majoco]

I used the thin wire stripped out of an old printer cable. As long as you cover the transformer in non-acid silicon sealant (after an initial test of course!) there shouldn't be a problem. Mine has been up on the house roof for about four years now and not even in a waterproof box - the coax cable is soldered to the transformer and that is also inside the silicon sealant blob.

 

[Token]

When making a balun of the kind you describe you are most often making a transformer. With a transformer you often want the windings physically close or even touching, but you do NOT want shorting (conduction) between the windings or between the wire and the core. Enameled wire has a thin layer of insulation on the surface to allow this type of use, physically close and touching without shorting. Enameled wire is also called "transformer wire" or "magnet wire", since it is often used to make transformers and electromagnets.

T!

 

[mmckenna]

Don't forget that a good/free source of this stuff is from old transformers. I've salvaged a few old transformers out of power supplies just to have a source of free enameled wire. There can be a few hundred feet on some of the larger ones.

Other sources are chokes and electric motor windings.

 

[chrissim]

Thank you both for your replies. I should probably get the ARRL Antenna Book, though I'm betting it's filled with the type of information that would leave me scratching my head.

The 'net is a great resource for information, but so much of it is conflicting. Yesterday I read that using a 9:1 balun (or transformer) and a long wire never yields the SWR that manufacturers claim, though for receiving I doubt that it matters as much. Yet, there are those that swear by them.

Years ago I got into astrophotography. As technical as it was, the standards for shooting lights, darks, stacking and aligning photos was pretty much the same across the board. But with the radio hobby, there's so much conflicting information - and much of it has merit, that I'm always left uncertain. Sorry, slightly off topic.

For portable use, I can't think of any other type of antenna that would be as convenient.

Again, thanks for the information.

 

[majoco]

I made mine from an article by John Bryant, Bill Bowers and Nick Hall-Patch. If insulated stranded wire is good enough for them, well, it's good enough for me.

www.dxing.info/equipment/impedance_transformer_bryant.doc

www.dxing.info/equipment/impedance_transformer_bryant2.doc

 

[Thayne]

When making a balun of the kind you describe you are most often making a transformer. With a transformer you often want the windings physically close or even touching, but you do NOT want shorting (conduction) between the windings or between the wire and the core. Enameled wire has a thin layer of insulation on the surface to allow this type of use, physically close and touching without shorting. Enameled wire is also called "transformer wire" or "magnet wire", since it is often used to make transformers and electromagnets.

T!

Bingo, this is the best answer IMHO. another reason is for RF it would increase the Q or efficiency of whatever the balun is for--