Low-loss toroids
 

Hi all,

I've been trawling through my various catalogues tonight looking for
toroids that might be suitable to wind hi-Q inductors around, but am
disappointed to see that all the stuff on offer seems to be geared
around interference suppression and is consequently - I assume - very
lossy material. Does anyone know of a source in the UK that can supply
small, *low-loss* toroids by the dozen to the hobbyist via mail order?

Thanks,

p.
--

The BBC: Licensed at public expense to spread lies.

Paul,

You need to look at powdered iron cores instead of ferrites.

K5HJ

"Paul Burridge" wrote in message
...
Hi all,

I've been trawling through my various catalogues tonight looking for
toroids that might be suitable to wind hi-Q inductors around, but am
disappointed to see that all the stuff on offer seems to be geared
around interference suppression and is consequently - I assume - very
lossy material. Does anyone know of a source in the UK that can supply
small, *low-loss* toroids by the dozen to the hobbyist via mail order?

Thanks,

p.
--

The BBC: Licensed at public expense to spread lies.

Paul,

You need to look at powdered iron cores instead of ferrites.

K5HJ

"Paul Burridge" wrote in message
...
Hi all,

I've been trawling through my various catalogues tonight looking for
toroids that might be suitable to wind hi-Q inductors around, but am
disappointed to see that all the stuff on offer seems to be geared
around interference suppression and is consequently - I assume - very
lossy material. Does anyone know of a source in the UK that can supply
small, *low-loss* toroids by the dozen to the hobbyist via mail order?

Thanks,

p.
--

The BBC: Licensed at public expense to spread lies.

Yes, powdered iron (I believe it's "iron dust" in the Queen's English)
is what you want. The major manufacturer of suitable cores is
Micrometals. Their products are sold by Amidon and others. Give their
web site a look for general info, and a google search should yield some
retail sources. For HF work, type 6 generally gives the highest Q, with
type 2 in second place.

Roy Lewallen, W7EL

Charles R. Ott wrote:
Paul,

You need to look at powdered iron cores instead of ferrites.

K5HJ

Yes, powdered iron (I believe it's "iron dust" in the Queen's English)
is what you want. The major manufacturer of suitable cores is
Micrometals. Their products are sold by Amidon and others. Give their
web site a look for general info, and a google search should yield some
retail sources. For HF work, type 6 generally gives the highest Q, with
type 2 in second place.

Roy Lewallen, W7EL

Charles R. Ott wrote:
Paul,

You need to look at powdered iron cores instead of ferrites.

K5HJ

In article , Roy Lewallen
writes:

Yes, powdered iron (I believe it's "iron dust" in the Queen's English)
is what you want. The major manufacturer of suitable cores is
Micrometals. Their products are sold by Amidon and others. Give their
web site a look for general info, and a google search should yield some
retail sources. For HF work, type 6 generally gives the highest Q, with
type 2 in second place.

Quite so, Roy!

Micrometals website is - http://www.micrometals.com

The website has a nice, free, downloadable program for calculating
the number of turns for any of their toroidal cores for any of their
powder mixes for many sizes of magnet wire.

One of their publications is the venerable "Q Book" which graphs
the Q of many different inductances wound on their forms over
frequency from LF to UHF. If Paul can talk them out of a copy
he will find it indispensable for estimating toroidal inductors...
provided there is a supplier on his side of the pond.

Amidon is a reseller (Micrometals' minimum order is at least 100
of any type, or was). Most of the small quantities found in ham
and electronics stores here have some typical Q curves enclosed
in the plastic packet, curves originally from Micrometals.

Len Anderson
retired (from regular hours) electronic engineer person

In article , Roy Lewallen
writes:

Yes, powdered iron (I believe it's "iron dust" in the Queen's English)
is what you want. The major manufacturer of suitable cores is
Micrometals. Their products are sold by Amidon and others. Give their
web site a look for general info, and a google search should yield some
retail sources. For HF work, type 6 generally gives the highest Q, with
type 2 in second place.

Quite so, Roy!

Micrometals website is - http://www.micrometals.com

The website has a nice, free, downloadable program for calculating
the number of turns for any of their toroidal cores for any of their
powder mixes for many sizes of magnet wire.

One of their publications is the venerable "Q Book" which graphs
the Q of many different inductances wound on their forms over
frequency from LF to UHF. If Paul can talk them out of a copy
he will find it indispensable for estimating toroidal inductors...
provided there is a supplier on his side of the pond.

Amidon is a reseller (Micrometals' minimum order is at least 100
of any type, or was). Most of the small quantities found in ham
and electronics stores here have some typical Q curves enclosed
in the plastic packet, curves originally from Micrometals.

Len Anderson
retired (from regular hours) electronic engineer person

"Paul Burridge" wrote in message
...
Hi all,

I've been trawling through my various catalogues tonight looking for
toroids that might be suitable to wind hi-Q inductors around, but am
disappointed to see that all the stuff on offer seems to be geared
around interference suppression and is consequently - I assume - very
lossy material. Does anyone know of a source in the UK that can supply
small, *low-loss* toroids by the dozen to the hobbyist via mail order?

http://www.sycomcomp.co.uk/

Leon

"Paul Burridge" wrote in message
...
Hi all,

I've been trawling through my various catalogues tonight looking for
toroids that might be suitable to wind hi-Q inductors around, but am
disappointed to see that all the stuff on offer seems to be geared
around interference suppression and is consequently - I assume - very
lossy material. Does anyone know of a source in the UK that can supply
small, *low-loss* toroids by the dozen to the hobbyist via mail order?

http://www.sycomcomp.co.uk/

Leon

For years Amidon was pretty much the only place hams bought ferrite and
powdered iron cores. A different company sprang up a few years back,
composed of some former Amidon associates as well as former Amidon
employees, and they are selling the same things. (Their reasons for going
out on their own involves, I believe, discontent with their relationships
with their former company, something which is hardly uncommon in the
business world.)

The name is Bytemark, or more properly CWS Bytemark, since it merged with
CWS a while back.

The URL is http://www.bytemark.com/ and the site has a lot of technical info
on the toroids.

At least one of them is a ham, Tracy Markham, N4LGH, who was the driving
force behind the original Bytemark. He's a homebrewer and was active on the
QRP mail reflector for a few years.