[Amps] (Perhaps) A plate choke too far ...

[Radio WC6W]

   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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