My favorite source for small quantities of Fair-Rite cores is Arrow
Electronics. They don't show stock on the 2.4" ferrite but their price
is $5.32 for one, and if you open an account (easy) the price drops to
$4.75.
My favorite #31 part is the round snap-on #0431176451 which has even higher
impedance than the "Big" snap-on but has a smaller inner diameter of just
under 3/4". It works great for smaller cables. The Arrow price with an
account is $4.77...and they have 649 in stock.
---
Chuck, AE4CW
-----Original Message-----
From: rfi-bounces@contesting.com [mailto:rfi-bounces@contesting.com] On
Behalf Of rfi-request@contesting.com
Sent: Monday, January 30, 2012 3:01 PM
To: rfi@contesting.com
Subject: RFI Digest, Vol 108, Issue 25
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Today's Topics:
1. 2.4" OD #31 toroids (Pete Smith N4ZR)
2. Re: 2.4" OD #31 toroids (Pete Smith N4ZR)
3. Re: 2.4" OD #31 toroids (Howard Lester)
4. Re: 2.4" OD #31 toroids (Tom Thompson)
5. Re: 2.4" OD #31 toroids (Jim Brown)
----------------------------------------------------------------------
Message: 1
Date: Mon, 30 Jan 2012 08:24:56 -0500
From: Pete Smith N4ZR <n4zr@contesting.com>
Subject: [RFI] 2.4" OD #31 toroids
To: RFI List <rfi@contesting.com>
Message-ID: <4F269A28.9080708@contesting.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Does anyone have a source for these? I can't even find them on the
Fair-Rite web site any more. I want to build a couple of super-good
common-mode chokes of the ON4UN/K9YC-recommended split type with ground
in between, wound with RG-59, and assume these cores will work fine.
Also, since this is a receiving application, I assume I can get by with
a single core to keep the cost and bulk down. Wrong?
73, Pete N4ZR
The World Contest Station Database, updated daily at www.conteststations.com
The Reverse Beacon Network at http://reversebeacon.net, blog at
reversebeacon.blogspot.com,
spots at telnet.reversebeacon.net, port 7000 and
arcluster.reversebeacon.net, port 7000
------------------------------
Message: 2
Date: Mon, 30 Jan 2012 09:09:56 -0500
From: Pete Smith N4ZR <n4zr@contesting.com>
Subject: Re: [RFI] 2.4" OD #31 toroids
To: Don Nelson <n0ye@comcast.net>, RFI List <rfi@contesting.com>
Message-ID: <4F26A4B4.8080703@contesting.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Thanks, Don - that's the right part, all right, but so far Amidon, Arrow
and Mouser all don't recognize the number. I'll keep looking.
73, Pete N4ZR
The World Contest Station Database, updated daily at www.conteststations.com
The Reverse Beacon Network at http://reversebeacon.net, blog at
reversebeacon.blogspot.com,
spots at telnet.reversebeacon.net, port 7000 and
arcluster.reversebeacon.net, port 7000
On 1/30/2012 8:38 AM, Don Nelson wrote:
> On 1/30/2012 6:24 AM, Pete Smith N4ZR wrote:
>> Does anyone have a source for these? I can't even find them on the
>> Fair-Rite web site any more. I want to build a couple of super-good
>> common-mode chokes of the ON4UN/K9YC-recommended split type with ground
>> in between, wound with RG-59, and assume these cores will work fine.
>> Also, since this is a receiving application, I assume I can get by with
>> a single core to keep the cost and bulk down. Wrong?
>>
>> 73, Pete N4ZR
>> The World Contest Station Database, updated daily at
>> www.conteststations.com
>> The Reverse Beacon Network at http://reversebeacon.net, blog at
>> reversebeacon.blogspot.com,
>> spots at telnet.reversebeacon.net, port 7000 and
>> arcluster.reversebeacon.net, port 7000
>> _______________________________________________
>> RFI mailing list
>> RFI@contesting.com
>> http://lists.contesting.com/mailman/listinfo/rfi
>>
> Pete,
>
> The last toroids I ordered were material type 31. These are made by
> Fair-rite with a part number 2831803802. The web page at Fair-rite is
>
http://www.fair-rite.com/cgibin/catalog.pgm?THEONEPART=2631803802&SEARCHAGAI
N=Y#select:onepart.
>
>
> Fair-rite does not use the T240 designation because that may be a copy
> righted designation by Amadon.
>
> I ordered these toroids from Arrow Electronics. At the time the cost
> was less than $7 each.
>
> Don
>
>
------------------------------
Message: 3
Date: Mon, 30 Jan 2012 09:18:23 -0500
From: Howard Lester <howard220@gmail.com>
Subject: Re: [RFI] 2.4" OD #31 toroids
To: Pete Smith N4ZR <n4zr@contesting.com>
Cc: RFI List <rfi@contesting.com>
Message-ID:
<CAK0FrPi6hveTNwAwNe2UPhY-b8P8681y11AaYRV0Ak4tVD9QXw@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Pete, isn't this what you want?
http://www.mouser.com/Search/ProductDetail.aspx?qs=P8bU7i9nNAWMk1EJQzshLg%3D
%3D
It says it's 61mm diameter and 12.7mm "long."
Howard N7SO
------------------------------
Message: 4
Date: Mon, 30 Jan 2012 07:27:51 -0700
From: Tom Thompson <tlthompson@qwest.net>
Subject: Re: [RFI] 2.4" OD #31 toroids
To: Pete Smith N4ZR <n4zr@contesting.com>
Cc: RFI List <rfi@contesting.com>
Message-ID: <4F26A8E7.7060001@qwest.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Pete,
Mouser part number
623-2631803802
They have over 4000 in stock at $7.00
Tom W0IVJ
On 1/30/2012 6:24 AM, Pete Smith N4ZR wrote:
> Does anyone have a source for these? I can't even find them on the
> Fair-Rite web site any more. I want to build a couple of super-good
> common-mode chokes of the ON4UN/K9YC-recommended split type with ground
> in between, wound with RG-59, and assume these cores will work fine.
> Also, since this is a receiving application, I assume I can get by with
> a single core to keep the cost and bulk down. Wrong?
>
> 73, Pete N4ZR
> The World Contest Station Database, updated daily at
www.conteststations.com
> The Reverse Beacon Network at http://reversebeacon.net, blog at
> reversebeacon.blogspot.com,
> spots at telnet.reversebeacon.net, port 7000 and
> arcluster.reversebeacon.net, port 7000
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>
------------------------------
Message: 5
Date: Mon, 30 Jan 2012 10:04:35 -0800
From: Jim Brown <jim@audiosystemsgroup.com>
Subject: Re: [RFI] 2.4" OD #31 toroids
To: rfi@contesting.com
Message-ID: <4F26DBB3.9020600@audiosystemsgroup.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 1/30/2012 5:24 AM, Pete Smith N4ZR wrote:
> Does anyone have a source for these?
See Appendix One of http://audiosystemsgroup.com/RFI-Ham.pdf for part
numbers and reliable sources. I've done well for moderate quantities
with Kreiger, which is in the Roanoke area. It pays to shop around --
the prices can vary depending on what they have in stock, left over from
a big order they bought for another customer.
Yes, you want the #31 material, and the most useful sizes are the 2.4-in
i.d. toroids and the 1-inch i.d. "biggest clamp-ons" listed in the
Appendix. Study the graphs of Z vs frequency and number of turns to
guide you in winding the chokes. Yes, a single core is enough IF you
can get enough turns on it. RG58 would make that easier, and this would
be a great application for one of the bifilar chokes wound with THHN.
Make sure you're looking at the latest version. These chokes have been
in the tutorial for about a year and a half.
And the traditional ham vendors who advertise in QST (Amidon and their
ilk) are USELESS for these ferrite parts -- they are SALESMEN, not
engineers. There used to be a guy named Amidon who WAS an engineer, but
he's been dead a long time. My stuff has been on the internet for five
years, and they're still not stocking #31. AND their prices for what
they do sell are outrageous, more than double what you would pay from a
GOOD vendor like Mouser, Allied, Newark, Krieger, Lodestone, etc.
Another idea, Pete. You might consider a group purchase for PVRC and
other clubs near you. Between PVRC, FRC, and YCCC, you could build huge
quantity and get a great price. NCCC has done three big group purchases.
K6EU did a couple, I did the last one, about a year ago, and we were
able to get the 2.4-in toroids for $4.10 with shipping (we ordered 1,000
pieces). We bought direct from Fair-Rite, which is easy to do, but
requires that you spend at least $500 and buy in box quantities. We've
also found the best price on the big clamp-ons from distributors.
Fair-Rite will also ship to multiple locations, but always in box
quantities. I wouldn't push this too far, but it should be no problem to
ship to a single YCCC point, a single FRC point, and a single PVRC
point. For the NCCC order I did, I established a rule that distribution
would be only at club meetings. This was for my convenience, because I
didn't want to be in the shipping business, and also because ferrite
parts are quite brittle, and must be very carefully packed.
73, Jim K9YC
------------------------------
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