If avoiding saturation is the point, how about using a ferrite rod
instead of a toroid?
Or using a toroid but cutting a small gap into it (with an abrasive disc)?
Angel Vilaseca HB9SLV
Radio WC6W a écrit :
> The other day, just for fun, I swept a bunch of ol' RF chokes -- solenoid
> wound, pie wound, etc. All of them exhibited nasty resonances somewhere
> within the HF spectrum.
>
> I then wound a few experimental coils on some toroids and one on a type 43
> core worked exceptionally well -- very flat response with no resonances
> anywhere below 50 Mhz.
>
> The only gotcha with this part is that in a real world application the DC
> plate current would saturate the toroid, killing the mu & the uH's.
>
> Now here's where this concept crosses over in the silly side...
>
> The saturation problem could be overcome by running an out of phase DC
> current, servoed by the plate I, through a 2nd winding on the core. This
> second winding would need to be RF isolated with a choke of its own but, for
> a single turn winding a 10uH (air core) choke would be sufficient. The
> required single turn current would be on the order of 10-15 amps. Sounds bad
> but, no real voltage is required -- 10 Amps at .1 volt is only a watt. In a
> fortunate circumstance, this current might be obtained "free" in series from
> a DC heater supply.
>
> Searchin' around the all knowing internet only uncovered a similar scheme
> to cancel the plate DC in an "audiophile" single ended output transformer.
>
> Has anyone ever see this done?
>
> 73 & Good evening,
> Marv WC6W
>
> http://wc6w.50webs.com/
>
>
>
>
> *
>
>
>
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