Ferrite beads for Class E output transformers

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Ferrite beads for Class E output transformers

Postby kf1z » Thu May 24, 2007 10:12 pm

Newark has Fairrite beads for $2.51 for 2 pcs.
http://www.newark.com/jsp/Passives/Ferrites/FAIR+RITE/2643102002B/displayProduct.jsp?sku=91F6482


EMI Suppression Bead Ferrite
Ferrite Grade:43
Impedance:235ohm
Frequency:100MHz
Cable Diameter Max:0.505"
Size/Dimensions:1.02 x 0.505 x 1.125"



Seems like these would work just dandy...

The SB-1020 from CWS yes SB not FB
is still $1.50 each...
SB-1020-43 1.00 inch 0.500 inch 1.120 inch 1-hole 850 $1.50


Sure not a HUGE savings...but.... just thought I'd pass it along.......
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Postby frank carcia » Fri May 25, 2007 8:00 am

type 43 is ui=850

Years ago a guy was selling A637 cores at hostraders for a buck each. I still have a pile of them. ui=650 so you need a couple more in the stack to get enough l. I use 8 A637s when you need 6 thye 43s.
There are 16 in my 75 meter final and stay stone cold at 1 KW carrier.
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Postby Gilly » Thu May 31, 2007 5:33 am

frank carcia wrote:type 43 is ui=850

Years ago a guy was selling A637 cores at hostraders for a buck each. I still have a pile of them. ui=650 so you need a couple more in the stack to get enough l. I use 8 A637s when you need 6 thye 43s.
There are 16 in my 75 meter final and stay stone cold at 1 KW carrier.



Hi Frank


Can I use SB series toroids nstead of FB within too much difference


Wayne
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Postby kf1z » Thu May 31, 2007 7:02 am

I'm not Frank, but......

The SB series of beads is what I'm using... along with Steve QIX and many others.....


No difference, that I'm aware of between FB and SB

One is Ferrite Bead, the other is Suppresion Bead....

The SB-1020 is type 43 ferrite.....
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Postby frank carcia » Thu May 31, 2007 7:37 am

If it is the same material and same size it is ok as long as SB doesn't mean split bead because the air gap will give you less reactance.
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Postby kf1z » Thu May 31, 2007 7:37 pm

""If it is the same material and same size it is ok as long as SB doesn't mean split bead because the air gap will give you less reactance.""


That would be a problem......

But the CWS "SB-1020" that I referenced in the first post are solid.....
as are the Fairrite beads as well......
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Postby Gilly » Fri Jun 08, 2007 8:15 am

kf1z wrote:""If it is the same material and same size it is ok as long as SB doesn't mean split bead because the air gap will give you less reactance.""


That would be a problem......

But the CWS "SB-1020" that I referenced in the first post are solid.....
as are the Fairrite beads as well......



Hi Bruce


Thanks for the information regarding the SB-43-1020...

Have ordered 24!! more then enough but they are expensive here in Aus around AU$8.00 each..

Wayne
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Postby kf1z » Sun Dec 09, 2007 5:52 pm

So, today I did some testing with these ferrites..... (playing :) )

And found that there is a slight difference between the SB-1020 from CWS, and the Fairrite beads from Newark....

Took a 24" long piece of wire, and starting at one turn (pass through center) added one turn at a time...

Came up with these numbers (crappy L meter ....)

Fairrite #2643102002B # turns SB-1020 CWS Bytemark


6.3uH.............................1.......................5.9uH
12.9................................2.......................10.8
24.2................................3.......................18.5
40.1................................4.......................28.9
60.4................................5.......................42.5
85.4................................6.......................59
115.4...............................7.......................78.5


And with a 12" piece of wire through 4 cores....

The CWS cores measured 9.2uH
And the Fairrite cores 12.1uH


So, in most cases I don't think this would make much difference...

But found it interesting....
Last edited by kf1z on Tue Dec 11, 2007 3:35 pm, edited 1 time in total.
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Postby frank carcia » Tue Dec 11, 2007 2:13 pm

Remember inductance will be lower when you crank 50 amps DC through your transformer. Good info though.
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