[HomeBrew] Torroids in vacuum tube circuits

[James Kearman]

rrfowler at bellsouth.net wrote:
> Can't remember if this has been discussed before, but has anyone ever tried using ferrite or iron core toroids instead of solenoidal air wound coils in plate and grid tuned circuits before?? I have been pondering building a HB vacuum tube receiver and would like to use them in the preselector (RF amp) tuned circuits. Anyone with this experience???

The powdered-iron cores are used in the output pi-L networks of 
high-power HF amplifiers to get the inductance needed for 160 M in a 
compact enclosure. RF doesn't see the core, only the inductance. 
Assuming you stay within the current limits above which a core may 
saturate, and the applied peak voltage isn't high enough to cause 
breakdown between individual turns, there's no reason you can't use them 
in tube circuits.

73,

Jim, KR1S