Resonance frequency is meant between WFC and choke (56) behind diode.
P.3-8 ¶3 and 3-38 Figure 21 and p.3-4 Figure 27
Choke (56) being made of resistive wire aids amp restriction. P. 3-10 ¶2.
Meyers encased his tubes with Delrin plastic to prevent electron leakage.
P.3-10 ¶5 to p.3-11 ¶1