[RFI] looking for larger size ferrites

[Grant Saviers]

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 at arrl.org
> World Wide Web: www.arrl.org
> 
> 
> 
> -----Original Message-----
> From: RFI <rfi-bounces+pcianciolo=arrl.org at contesting.com> On Behalf Of Jim Brown
> Sent: Friday, May 1, 2020 5:10 PM
> To: rfi at 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) _______________________________________________
> RFI mailing list
> RFI at contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
> _______________________________________________
> RFI mailing list
> RFI at contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>