Message

Date

From

Subject

9862

2014-03-24 04:42:02

jmlcs2000

FT37-J core

I am looking for four FT37-J cores for future projects and hopeing that someone might have some extras that they will not need laying around in their Junkbox. I am willing to pay a fair price for them. I have checked Kits and Parts (they don't carry this size), Ebay, as well as other vendors and they either do not carry this part or it is too expensive to purchase from them. If you can help, please email me off line at JMLCS2000@Yahoo.com. Thank you, John, K5IRK

9864

2014-03-24 11:41:22

Roelof Bakker

Re: FT37-J core

Hello John,

Will a FT-37-77 do?

73,
Roelof, pa0rdt

9866

2014-03-24 15:17:01

kerrypwr

Re: FT37-J core

Amidon "J" and "75" materials are the same.

FT37-75 toroids seem to be readily available, eg;

http://www.alltronics.com/cgi-bin/category.cgi?&category=80&start=20

who also sell on ebay;

http://www.ebay.com.au/itm/Amidon-Ferrite-Torroids-FT-37-75-Pkg-of-4-/161185064559?pt=LH_DefaultDomain_0&hash=item258760e66f

Kerry VK2TIL.

9867

2014-03-24 16:27:32

jmlcs2000

Re: FT37-J core

HI Roelof.....thank you for the reply. No, the AL value of the 77 core is about one half that of the J core according to the Amidon website.....If all possible, I would really like to have the J core for future needs, but I really do appreciate you thinking of me and replying. I hope you have a good week, thanks, John

9868

2014-03-24 19:46:59

John Lawson

Re: FT37-J core

Kerry, many thanks, I was not aware of this vendor..I'll follow up on your suggestion. John

Sent from my iPad

9870

2014-03-26 18:36:07

Garry Taylor

Re: FT37-J core

Here is a useful table for those that may not have seen it before. It does note that type 75 and J are the same.

Properties	Material
Properties	31¹	43	61	64	67	68	72	73	77	F	J/75	W	H
Initial Perm. (µ_i)	1500	850	125	250	40	20	2000	2500	2000	3000	5000	10000	15000
Max. Perm. (µ_max)	n/a	3000	450	375	125	40	3500	4000	6000	4300	9500	20000	23000
Max. Flux Density @ 10oer. (gauss)	3800	2750	2350	2200	3000	2000	3500	4000	4600	4700	4300	4300	4200
Residual Flux Density (gauss)	2900	1200	1200	1100	1000	1000	1500	1000	1150	900	500	800	800
Vol. Resistivity (ohm-cm)	3x10³	1x10⁵	1x10⁸	1x10⁸	1x10⁷	1x10⁷	1x10²	1x10²	1x10²	1x10²	1x10²	.15x10²	.1x10²
Temp. Coeff. (%/C) -20 to 70 °C	n/a	1	0.15	0.15	0.13	0.06	0.6	0.8	0.25	0.25	0.4	0.4	0.4
Loss Factor (x 10^-6)	20@ 0.1MHz	120@ 1MHz	32@ 2.5MHz	100@ 2.5MHz	150@ 50MHz	400@ 100MHz	5.0@ 0.1MHz	7.0@ 0.1MHz	4.5@ 0.1MHz	4.0@ 0.1MHz	15@ 0.1MHz	7@ 10kHz	15@ 10kHz
Coercive Force (Oersteds)	0.35	0.3	1.6	1.4	3	10	0.25	0.18	0.22	0.2	0.1	.04	.04
Curie Temp. (°C)	>130	130	350	210

9871

2014-03-26 19:21:51

kerrypwr

Re: FT37-J core

A useful table Garry.

I have several similar in my 360GB of fwerrite data. :)

There are several ferrite materials these days that are designated by letters instead of numbers; I think that these are Fair-Rite products although none are mentioned in the Fair-Rite catalogue.

I have just asked Fair-Rite if they are that company's products and, if so, where their properties may be found.

The Fair-Rite catalogue may be downloaded from their site; it contains a lot of good information on ferrite materials.

Kerry.

9872

2014-03-27 06:27:17

john lawson

Re: FT37-J core

Hi to everyone, I want to thank you for your comments and the table to my post, it's appreciated. Hope all of you have a good day, John K5IRK

Sent from Yahoo Mail on Android

9874

2014-03-27 13:12:50

kerrypwr

Re: FT37-J core

I received this reply from Fair-Rite;

****************************
Fair-Rite designates it materials by number. Two companies, Ferronics and Magnetics Inc designate a "J" material. For the Ferronics "J" material our comparable material is 43. For Magnetics, Inc "J" material, our comparable material is 75.

***************************

I found in my files the table that Garry posted; it seems to have originated from Amidon.

These are also Amidon documents;

http://i59.tinypic.com/a11pgk.jpg

http://i59.tinypic.com/qn2uth.jpg

which include other "letters".

Amidon, so far as I know, don't make ferrites; they source them. They must buy their "J" material items from Magnetics.

My conclusion is that "J" = "75" with certainty only if the "J" item is bought from Amidon.

That, of course, is very likely since most or all of the ferrites we amateurs get seem to originate from Amidon.

But ferrites are a minefield, albeit for me, at least, a fascinating one.

Kerry.

9875

2014-03-27 17:27:52

john lawson

Re: FT37-J core

Kerry many thanks, this information should be of a help to all of us.....John

On Thursday, March 27, 2014 4:12 PM, "planningpower@iprimus.com.au" wrote:

9885

2014-03-30 15:09:24

Garry Taylor

Re: FT37-J core

The table was formatted in HTML and not everyone will have been able to view it. If you would like a copy let me know and I can send a PDF version.

I did not produce the table and while it does appear to be very similar to the Amidon one, I got it from a Neosid web site. Not sure why Neosid posted it, as none of their ferrite materials match to the "standard" Amidon numbers. It also appears that this table is no longer on their web site. www.neosid.com.au.

Cheers

Garry

9886

2014-03-30 20:07:51

kerrypwr

Re: FT37-J core

There is a typo in the table I think; "311" material should be "31".

Some of the figures are slightly-different to the figures given in the Fair-Rite catalogue but this is the nature of ferrites; there is quite wide tolerance in properties like permeability and there is a good deal of variation between batches of the same material.

I was puzzled at one stage when my tests of 43 material showed different characteristics to those given in the catalogue; Jack K8ZOA told me that Fair-Rite had changed the formulation without, it seems, telling anyone.

Jack has recorded this here;

http://www.cliftonlaboratories.com/estimating_q_of_ferrite_cores.htm

And I've just realised that I exaggerated the size of my data-file on ferrite & iron in my earlier post; 360 GB of data is hardly possible; I have 362 MB which is still a great deal.

Kerry.

9887

2014-03-31 08:39:55

Jim Strohm

Re: FT37-J core

Actually, a 360 GB data store is quite possible these days -- I have a 1.87 TB formatted size USB HD for portable backup, and two 2 TB drives in RAID configuration in my wireless backup system.

Today's biggest restrictions on file system size (and consequently file size) are now in the microprocessors and operating systems most commonly in use.

73

Jim N6OTQ

9888

2014-03-31 08:52:21

Andy

Re: FT37-J core

"There is a typo in the table I think; "311" material should be "31"."

Actually, that "311" you saw was a "31" but with a small superscript "1" after it. I guess your reader didn't translate the HTML fully.

I did not see a footnote to go with it, but there probably was one in the document this was taken from.

Andy

9889

2014-03-31 09:20:12

Dana Myers

Re: FT37-J core

9890

2014-03-31 13:07:05

kerrypwr

Re: FT37-J core

No; what I was describing was the size of the file folder in which I store data & information on ferrite & iron materials in the form of pdf, jpg and other file types.

360 GB of such files is unlikely; I mis-typed GB when I should have typed MB.

360 MB of files is still a lot of information on a single subject; perhaps it's indicative of how complicated these little grey things really are! :)

I'm a great collector of information on the many things, not just electronics, that interest me; my Electronics folder in My Documents is 19 GB whilst the My Documents folder itself is 118 GB.

Kerry.

9891

2014-03-31 13:11:35

Jim Strohm

Re: FT37-J core

And while 118 GB is not such a large volume in and of itself nowadays, it takes a significant amount of file collecting to amass that much data in individual files.

73

Jim N6OTQ

9892

2014-03-31 18:30:49

Dana Myers

Re: FT37-J core

9893

2014-03-31 19:39:32

EricJ

Re: FT37-J core

That would be quite a fantasy, I think. I was involved in interfacing a very large EAI 8800 analog computer with a CDC 6600 (??) digital computer at Bell Labs in the late 60s. I believe it had 1 MB of core memory (I was the analog field engineer so my wetware memory is a little hazy about the digital side). As I remember it, core memory was made up of a stack of 4x4 inch 4K core memory boards. This was 4K of 56 or maybe 60 bit words. So 1 MB would have taken up a bit of real estate. That was a LOT of memory in those days so it would be difficult to imagine anything then even approaching 360 MB. 360 GB would probably have been more than even an Arthur C. Clarke novel would have envisioned.

Eric
KE6US

9894

2014-03-31 20:42:44

Andy

Re: FT37-J core

Do you suppose as much as 360 GB of core memory has been made, in the history of making it?

Just a wild thought ... sorry.

Andy

9895

2014-03-31 20:46:55

Dana Myers

Re: FT37-J core

9896

2014-03-31 20:48:25

Dave

Re: FT37-J core

We had a 6600 in college(1969-1971) at UC Berkeley. It was 60 bit and had a whopping 120K words. Spent a number of all nighters in the computer center!

Dave - WB6DHW

9897

2014-03-31 20:50:10

jim

Re: FT37-J core

-----------------------------------------

9898

2014-03-31 22:17:06

Andy

Re: FT37-J core

I was working with 360MB.

What kind of space did that take up, and any idea what it cost?

Andy

9899

2014-03-31 22:27:11

Dana Myers

Re: FT37-J core