On Mon, 21 Apr 2008 10:21:36 -0400, "J. Mc Laughlin"
wrote:

SNIP

P.S. I will also appreciate ideas about places to purchase ferrite in
addition to Mouser.

also check: www.palomar-engineers.com

Bruce W0BF

Dear Bruce: Thank you. I shall do so. My recollection is that their
prices were on the high side, but that needs to be checked.

Warm regards, Mac N8TT

--
J. McLaughlin; Michigan, USA
Home:
"Bruce W. Ellis" wrote in message
...

On Mon, 21 Apr 2008 10:21:36 -0400, "J. Mc Laughlin"
wrote:

SNIP

P.S. I will also appreciate ideas about places to purchase ferrite in
addition to Mouser.

also check: www.palomar-engineers.com

Bruce W0BF

Dear Bruce: As a follow-up: No type 31 at Palomar. 73, Mac N8TT

--
J. McLaughlin; Michigan, USA
Home:
"Bruce W. Ellis" wrote in message
...

On Mon, 21 Apr 2008 10:21:36 -0400, "J. Mc Laughlin"
wrote:

SNIP

P.S. I will also appreciate ideas about places to purchase ferrite in
addition to Mouser.

also check: www.palomar-engineers.com

Bruce W0BF

J. Mc Laughlin wrote:
I looked through saved messages and the only reference to type 31 ferrite
(Fair-Rite) was in March of 2005. That reference had to do with ignition
wires.

Recommendations for HF choking ferrites have centered on the 70 series with
type 43 being favorably recommended for the upper portion of HF and VHF.
However, Fair-Rite seems to be recommending type 31 for HF. See Figure 26
in:
http://www.fair-rite.com/newfair/pdf/CUP%20Paper.pdf

Am I missing something? It seems to me that for the purpose of choking
common mode current (on the outside of the outer conductor of coax) from 3
to 25 MHz one should prefer the use of type 31. This is a receiving
application with a long run of coax.

73, Mac N8TT

P.S. I will also appreciate ideas about places to purchase ferrite in
addition to Mouser.

A fairly brief look at the graphs (Figs. 6 - 8) shows that type 31 has
roughly the same or a little higher total complex permeability than 73
over most of the lower HF range and same or higher than 43 on up to 100
MHz. So it should be a good ferrite to use for very wide band
applications. However, Table 1 shows that it's available in large parts
only. Type 43 is very widely available in a wide variety of sizes, so
you might have a lot more luck getting cores of the sizes you need in
type 43.

Roy Lewallen, W7EL

Roy Lewallen wrote:

A fairly brief look at the graphs (Figs. 6 - 8) shows that type 31 has
roughly the same or a little higher total complex permeability than 73
over most of the lower HF range and same or higher than 43 on up to 100
MHz. So it should be a good ferrite to use for very wide band
applications. However, Table 1 shows that it's available in large parts
only. Type 43 is very widely available in a wide variety of sizes, so
you might have a lot more luck getting cores of the sizes you need in
type 43.

Roy Lewallen, W7EL


Amidon do stock some type 31 products, including FT-240-31 toroids and
the large beads for RG213, but they aren't listed on the website.

Part numbering is the same as normal, so simply substitute a "31" in the
part number you wish to order, and then call 1-800-898-1883.


--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Dear Ian (also my father's name): Thank you for your note. It is a
mystery to me why those who sell via the Internet do not work hard at
keeping their sites up-to-date. 73, Mac N8TT

--
J. McLaughlin; Michigan, USA
Home:
"Ian White GM3SEK" wrote in message
...
Roy Lewallen wrote:

A fairly brief look at the graphs (Figs. 6 - 8) shows that type 31 has
roughly the same or a little higher total complex permeability than 73
over most of the lower HF range and same or higher than 43 on up to 100
MHz. So it should be a good ferrite to use for very wide band
applications. However, Table 1 shows that it's available in large parts
only. Type 43 is very widely available in a wide variety of sizes, so you
might have a lot more luck getting cores of the sizes you need in type 43.

Roy Lewallen, W7EL


Amidon do stock some type 31 products, including FT-240-31 toroids and the
large beads for RG213, but they aren't listed on the website.

Part numbering is the same as normal, so simply substitute a "31" in the
part number you wish to order, and then call 1-800-898-1883.


--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

J. Mc Laughlin wrote:
Dear Ian (also my father's name): Thank you for your note. It is a
mystery to me why those who sell via the Internet do not work hard at
keeping their sites up-to-date. 73, Mac N8TT


Amidon is sort of on-again/off-again when it comes to supporting the
retail ham market. Sometimes they are pretty good, but other times
they're just terrible. Might have something to do with changes in
ownership and management over the years, or just whether they get busy
with bread and butter commerical customers. They've also used a wide
variety of suppliers over the years.

And the whole Amidon, Amidon Associates, Applied Magnetics, BTC Power
Electronics, Flat Transformer Technology, thing...

It's been a long time since Bill Amidon ran it from his garage in North
Hollywood providing retail distribution for Fair-Rite and Micrometals
products.

"J. Mc Laughlin" wrote in
:

Dear Ian (also my father's name): Thank you for your note. It is a
mystery to me why those who sell via the Internet do not work hard at
keeping their sites up-to-date. 73, Mac N8TT

Mac, If you have your heart set on #31 mix, this option isn't a good
one... but if you can use #73 or #43, you will regularly see sleeves in
various sizes and materials on Ebay. Many have Fair-rite numbers so you
can check to see if they suit.

Some advertisers state that the cores are Fair-rite cores, if they know
that, they should know the part numbers though they don't always state
them in the descriptions.

I have bought ferrites from one of the suppliers, the goods seem to
comply with the part number descriptions (dimensions, mu) and their
service to Australia was quick and cheap.

In this part of the world, product from Asia is available economically...
but we have to characterise them and long term product availability is a
bit of an issue.

Owen

Dear Owen: Always good to receive your insight.

Were I to deal with Ebay, I would have a dedicated computer and ISP just for
that purpose. I am much too much a belt and suspenders person to wish to
avail myself of their "bargains." I leave that to those who are younger.
You have reinforced my expectation that from VK land it simply might be a
necessity to deal with Ebay and to measure materials received from any
distant source.

As an extension, a new field proposed at our university is that of a
specialized engineer who is able to make the importation of parts from all
over the world work. This has become a real field. It is much worse than
the three metric systems that existed at the beginning of WW2 (American,
Canadian, and English) such that bolts might only engage a few threads
before seizing.

Your skepticism about type 31 causes me to revisit my assumptions.

As always, 73 Mac N8TT

--
J. McLaughlin; Michigan, USA
Home:
"Owen Duffy" wrote in message
...
"J. Mc Laughlin" wrote in
:

Dear Ian (also my father's name): Thank you for your note. It is a
mystery to me why those who sell via the Internet do not work hard at
keeping their sites up-to-date. 73, Mac N8TT

Mac, If you have your heart set on #31 mix, this option isn't a good
one... but if you can use #73 or #43, you will regularly see sleeves in
various sizes and materials on Ebay. Many have Fair-rite numbers so you
can check to see if they suit.

Some advertisers state that the cores are Fair-rite cores, if they know
that, they should know the part numbers though they don't always state
them in the descriptions.

I have bought ferrites from one of the suppliers, the goods seem to
comply with the part number descriptions (dimensions, mu) and their
service to Australia was quick and cheap.

In this part of the world, product from Asia is available economically...
but we have to characterise them and long term product availability is a
bit of an issue.

Owen

Roy Lewallen wrote:
J. Mc Laughlin wrote:

I looked through saved messages and the only reference to type 31
ferrite (Fair-Rite) was in March of 2005. That reference had to do
with ignition wires.

Recommendations for HF choking ferrites have centered on the 70 series
with type 43 being favorably recommended for the upper portion of HF
and VHF. However, Fair-Rite seems to be recommending type 31 for HF.
See Figure 26 in:
http://www.fair-rite.com/newfair/pdf/CUP%20Paper.pdf

Am I missing something? It seems to me that for the purpose of
choking common mode current (on the outside of the outer conductor of
coax) from 3 to 25 MHz one should prefer the use of type 31. This is
a receiving application with a long run of coax.

73, Mac N8TT

P.S. I will also appreciate ideas about places to purchase ferrite in
addition to Mouser.


A fairly brief look at the graphs (Figs. 6 - 8) shows that type 31 has
roughly the same or a little higher total complex permeability than 73
over most of the lower HF range and same or higher than 43 on up to 100
MHz. So it should be a good ferrite to use for very wide band
applications. However, Table 1 shows that it's available in large parts
only. Type 43 is very widely available in a wide variety of sizes, so
you might have a lot more luck getting cores of the sizes you need in
type 43.

Large, in this context, isn't all that big. You can't get it in tiny
ferrite beads to slip over a AWG30 wire. You can get it in 0.485" OD
0.5" long beads with a 0.2" hole in the middle.... $0.42 each from
Mouser. Similar snap on cases too..

Small, for Fair-rite, means things like those little 1/4" diameter multi
hole cores for making wound EMI filters, or chip components.

I buy it in 2.4" toroids so I can put multiple turns of coax on.