>
>Hi Marv,
>
>> permeability, it was likely greater than 100. Thus, the core is
>> intercepting relatively little of the magnetic field compared to a tight
>> winding. Additionally, rod cores with their open magnetic structure are
>> very difficult to saturate compared to a toroid or other closed loop form.
>
>Heating is always more of a problem than saturation, because of
>the finite Q of soft-iron cores. The usual exception is pulse duty.
>Most off the shelf rods have too much loss tangent at HF. They
>look like a resistor in series with an inductor.
>
>If you tell me the core material type number (assuming it is a
>standard number), I can tell you the Q or ratio of resistance to
>reactance. I'd bet it is pretty poor with an off-the-shelf rod at the
>high end of HF.
>
>> Since relatively little RF current flows through this coil, if things
>> are working correctly, the DC component probably creates more flux.
>
>The "dc" flowing through the core is time-varying at an RF rate.
Mr. Rauch -- Please explain the difference between ''varying'' and
''time-varying"".
thanks
>I'm afraid no matter what the impedance, you are stuck with a certain
>number of ampere-turns that are changing at an RF rate.
>
>> A tuned circuit is a much more demanding application... probably
>> requiring something in the neighborhood of 100x the power handling
>> capability.
>
>It always translates to volt-turns at a certain impedance, or ampere
>turns at a certain frequency. Q of a resonant system multiplies the
>problem because of increased VAR power.
>
>I would be skeptical of using random ferrite materials in a HV, high
>current application at RF. Ferrites do not get rid of heat well.
>
>
amen, Tom. And, as an added bonus, sellers of ferrite materials
typically have better specs. .than manufacturers.
later
>
>
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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