My CNC work has led me to RFI suppression ferrites for high power VFDs.
The TDK PC40 material is recommended and the data sheet shows higher
permeability and loss than #31. The available cores range from 51 to
104 mm OD. Some cores are available on Amazon and ebay at what seem to
be high prices.
Has anybody characterized these as alternatives to Fair-Rite #31?
Better or worse? I bought one to try but don't have the time right now
to test it.
https://product.tdk.com/info/en/catalog/datasheets/ferrite_mz_large_t_en.pdf
https://www.theferritegateway.com/uploads/datasheets/TDK/PC40.pdf
Grant KZ1W
On 5/4/2020 06:05, Cianciolo, Paul, W1VLF wrote:
Jim makes a bunch of good points here.
Take a look at the datasheet for the #31 snap on cores. Look on page 2, where
it show the series equivalent loss impedance for a single pass through the
core as a function of frequency.
Impedance is a the square of the turns ratio. At least for a first order
approximation. Jim's detailed papers can help you greatly beyond that.
https://www.newark.com/pdfs/datasheets/Fairrite/0431176451.pdf
73,
Paul Cianciolo, W1VLF
ARRL EMC Engineer
ARRL - The national association for Amateur RadioT
225 Main Street, Newington, CT 06111-1400 USA
Telephone: (860) 594-0392
FAX: (860) 594-0259
Email: w1vlf@arrl.org
World Wide Web: www.arrl.org
-----Original Message-----
From: RFI <rfi-bounces+pcianciolo=arrl.org@contesting.com> On Behalf Of Jim
Brown
Sent: Friday, May 1, 2020 5:10 PM
To: rfi@contesting.com
Subject: Re: [RFI] looking for larger size ferrites
What frequency(ies) are you trying to suppress? In general, simply clamping a
ferrite over coax or hard line is effective only from about
100-500 MHz, depending on the ferrite mix. Fair-Rite #31 or #43 below about 250
MHz, #61 above that. Multiple turns on Fair-Rite #31 are required below that
frequency.
http://k9yc.com/2018Cookbook.pdf
http://k9yc.com/ChokesVHF.pdf
I've found Arrow Electronics to be a great vendor for the the quantities of
parts that I need IF they have them in stock, and they stock a lot of
Fair-Rite. Shipping is free for a $50 order placed online. Other vendors and a
tutorial discussion of how ferrite chokes work are in this link.
http://k9yc.com/RFI-Ham.pdf
73, Jim K9YC
On 5/1/2020 11:56 AM, David Huff wrote:
> I am looking for a source of larger size ferrites, preferably clamp on
style big enough to go over LDF4-50 cable. (16 to 18mm Inside Diameter)
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