ferrite manuf.'s are limited in the ferrite materials they can use for spit
cores because of casting, permeability properties and machining
properties....few of the ferrite materials that exhibit high HF attenuation
are usable in spit cores.
measure them anyway you like, sig. generator and spectrum analyzer, network
analyzer, impedance bridge, vector impedance analyzer; none of the spit
cores exhibit cost effective usable HF attenuation below 20 MHz. except type
31 from Fair-Rite which is difficult to buy on the street. The Radio? Shack
versions have one of the lowest measured HF attenuation factors of commonly
available on the street retail ferrites, I refuse to waste money on them.
material 31 split cores are now avail from Amidon for the ham comm. in small
quantities, less than 1000
the original query was concerning HF overload of a computer speaker system,
not VHF.
Cliff N7HIY
----- Original Message -----
From: "m.ford" <k1ern@direcway.com>
To: <amps@contesting.com>
Sent: Tuesday, February 07, 2006 7:13 AM
Subject: [Amps] Fw: FW: RFI Question
>
> ----- Original Message -----
> From: "m.ford" <k1ern@direcway.com>
> To: "Jim Brown" <jim@audiosystemsgroup.com>
> Sent: Tuesday, February 07, 2006 10:11 AM
> Subject: Re: [Amps] FW: RFI Question
>
>
>>
>>
>>> On Tue, 7 Feb 2006 04:13:13 -0800, N7HIY wrote:
>>>
>>>>clip on ferrites are not very
>>>>effective...made for those looking for placebo effect...
>>>
>>> WRONG! Clip-on ferrites ARE effective for the frequencies for
>>> which they are designed -- VHF. They are NOT intended for HF,
>>> and they don't work at HF. See the tutorial on my website.
>>>
>>> http://audiosystemsgroup.com/publish
>>>
>>> Think of ferrites in the same way that you think of any other
>>> electrical component -- resistors, capacitors, and inductors all
>>> come in various values, sizes, and construction types, and so do
>>> ferrites. The differences is that ferrites aren't labeled with
>>> their values and types. They should be, but they are not.
>>>
>>> Jim Brown K9YC
>>>
>>
>> I have had great results from the rectangular snap on devices
>> sold by RS. Part # 273-104. You can wind many turns of just
>> about anything on them or stack em like flap jacks. I put one on
>> the primary leads of a transformer that was powered by a square
>> wave inverter and the thing started singing. Spooky.
>>
>> If anyone knows who makes them for RS I would like to know.
>>
>> Mike k1ern
>>
>>>
>>>
>>> _______________________________________________
>
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