[TowerTalk] Ferrite material Laird 28

Jim Brown jim at audiosystemsgroup.com
Mon Mar 27 19:36:47 EDT 2017


On Mon,3/27/2017 2:12 PM, Richard (Rick) Karlquist wrote:
> What I meant by loosier is that in a common mode
> choke, there would be more heat dissipation loss
> with the Laird.  I did NOT mean that the series
> resistance was higher.

Not necessarily. Remember that power is I squared R, and if R is 
sufficiently large, I falls to the point that power is small (because 
it's falling twice as fast as R increases). OTOH, that R is undesired 
when using the core in a real transformer (that is, the core carries all 
of the flux for the differential power). I know you know this, Rick, but 
this is for others on the reflector who may not.

73, Jim K9YC
>
> I agree Fair-Rite's web site is by far the best
> in the industry.
>
> 73
> Rick N6RK
>
> On 3/27/2017 12:07 PM, Jim Brown wrote:
>> On Mon,3/27/2017 4:46 AM, Richard (Rick) Karlquist wrote:
>>> I have measured various competitor's
>>> "equivalents" to material 43 and the found
>>> that they are considerably lossier.
>>
>> For common mode chokes, lossier is better. But so is the shape of the
>> curve of loss vs. frequency, and so is resonant frequency. You either
>> need to wind chokes and measure them or have graphs of mu' and mu'' vs
>> frequency to compare with the Fair-Rite materials. Laird's website
>> appears to be totally inscrutable with any of this, FAR, FAR, FAR behind
>> Fair-Rite's. Laird's seems to have been done by a data guy, Fair-Rite's
>> by an applications engineer who actually understands what's needed to
>> choose a part and design using it.
>>
>> 73, Jim K9YC
>>
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>



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