I like that picture.
What do I like about it?
A single dashed core line connecting the upper primary with the entire secondary.
To function, that is needed imho. Coupling from the tube, i.e., the winding in one hole, to the entire secondary through both holes.
Henning Paul DC4HP (npub1akz…cn50) Alexander Knochel (npub1dgh…gkrs) Rasmus "raek" [rɛːkʰ] SA5RJS (npub133k…fazx)