Discussion:
[Elecraft] Toroids
Trevor Day
2002-06-03 10:25:01 UTC
Permalink
With all the talk about toroids and baluns recently I decided to rifle
through the junk box looking for suitable cores. It appears that I have
plenty of all shapes and sizes but I have no idea of their individual
properties. Is there any way of identifying these unmarked devices so I
can put a few to good use?

Thanks,

Trev G3ZYY K2 2637
--
Trevor Day
Charles Greene
2002-06-03 10:59:01 UTC
Permalink
Trev,
Post by Trevor Day
With all the talk about toroids and baluns recently I decided to rifle
through the junk box looking for suitable cores. It appears that I have
plenty of all shapes and sizes but I have no idea of their individual
properties. Is there any way of identifying these unmarked devices so I
can put a few to good use?
Well, here's the way I do it. First you need a book or chart of Al vs size
and material. I use the Bytemark (formerly Amidon) data book, but there's
some other sources. Then I wind a few turns of enameled wire, size is not
important. I usually use #18 or so. Then measure the inductance using a
LCR meter or an antenna analyzer if it will measure inductance L. If I
guessed wrong and the reading is beyond the scale of the meter I am using,
I change the number of turns until I can get a good reading. Then plug in
the formula for inductance you will find in the data book or source of Al
values and solve for Al. Now with a value of Al and size, consult the
table of Al values and you can usually identify the material. If the
material or size is a discontinued item, use the nearest one. Better yet,
now that you have the Al value, you don't need anything else to calculate
how many turns you need for X inductance. You just need the material to
determine whether it is suitable for your application.

If some one has a simpler way, I'm listening.


73, Chas, W1CG
Sandy, W5TVW
2002-06-03 13:20:01 UTC
Permalink
If you have a way to measure inductance, you can tell which cores are ferrite and
which
are powdered iron easily by winding a test coil. The ferrite cores will have a much
higher inductance per turn! Best way really is to wind a balun with them and give
them a try! 8-12 turns is usually adequate (bifilar or trifilar depending on whether
you want 1:1 or 4:1)

73,
Sandy W5TVW
----- Original Message -----
From: "Trevor Day" <***@secornwall.com>
To: <***@mailman.qth.net>
Sent: Monday, June 03, 2002 4:18 AM
Subject: [Elecraft] Toroids


| With all the talk about toroids and baluns recently I decided to rifle
| through the junk box looking for suitable cores. It appears that I have
| plenty of all shapes and sizes but I have no idea of their individual
| properties. Is there any way of identifying these unmarked devices so I
| can put a few to good use?
|
| Thanks,
|
| Trev G3ZYY K2 2637
|
| --
| Trevor Day
|
| _______________________________________________
| Elecraft mailing list: ***@mailman.qth.net
| You must be a list member to post to the list.
| Postings must be plain text (no HTML or attachments).
| See: http://mailman.qth.net/mailman/listinfo/elecraft
| Elecraft Web Page: http://www.elecraft.com
|
|
Tom Hammond NØSS
2002-06-03 13:42:03 UTC
Permalink
Post by Trevor Day
With all the talk about toroids and baluns recently I decided to rifle
through the junk box looking for suitable cores. It appears that I have
plenty of all shapes and sizes but I have no idea of their individual
properties. Is there any way of identifying these unmarked devices so I
can put a few to good use?
I agree with Trevor...

It'd certainly be a GREAT idea if someone would/could come up with a
treatise, in layman's terms, and using (more or less) commonly available
equipment, to allow us to better identify the myriad toroids we might have
laying around the shack, and for which we have NO CLUE of their (even
approximate) properties. Now THAT would be a worthwhile article.

Anyone able to step up to the plate on this?

73,

Tom Hammond N0SS
Phil Wheeler
2002-06-03 15:28:00 UTC
Permalink
I'm not sure how universally applicable this info is, but the following=20
web page:

http://tritium.fis.unb.br/Fis3Exp/fcim.csdc.com/fcimis/compid/ind/toroid.=
html

does have some color coding and properties info. It might, at least,=20
give that initial clue re properties of some cores. I have an old=20
Amidon catablog with similar data.

73, Phil
Post by Tom Hammond NØSS
With all the talk about toroids and baluns recently I decided to=20
rifle through the junk box looking for suitable cores. It appears=20
that I have plenty of all shapes and sizes but I have no idea of=20
their individual properties. Is there any way of identifying these=20
unmarked devices so I can put a few to good use?
I agree with Trevor...
It'd certainly be a GREAT idea if someone would/could come up with a=20
treatise, in layman's terms, and using (more or less) commonly=20
available equipment, to allow us to better identify the myriad toroids =
we might have laying around the shack, and for which we have NO CLUE=20
of their (even approximate) properties. Now THAT would be a worthwhile =
article.
Bob Tellefsen
2002-06-03 16:23:00 UTC
Permalink
Trev
Yes, you can put "orphan" toroids or rods to work, if you have some test
equipment
to make measurements with.
I suggest an antenna analyzer along the lines of the Autek VA-1, the MFJ
units or the
AEA unit. You need something that will indicate reactance, not just swr.
If you have access to such equipment, let's talk further.
73, Bob N6WG

-----Original Message-----
From: elecraft-***@mailman.qth.net
[mailto:elecraft-***@mailman.qth.net]On Behalf Of Trevor Day
Sent: Monday, June 03, 2002 2:18 AM
To: ***@mailman.qth.net
Subject: [Elecraft] Toroids


With all the talk about toroids and baluns recently I decided to rifle
through the junk box looking for suitable cores. It appears that I have
plenty of all shapes and sizes but I have no idea of their individual
properties. Is there any way of identifying these unmarked devices so I
can put a few to good use?

Thanks,

Trev G3ZYY K2 2637

--
Trevor Day

_______________________________________________
Elecraft mailing list: ***@mailman.qth.net
You must be a list member to post to the list.
Postings must be plain text (no HTML or attachments).
See: http://mailman.qth.net/mailman/listinfo/elecraft
Elecraft Web Page: http://www.elecraft.com

Continue reading on narkive:
Loading...