It sounds like you might be referring to (sometimes spelled Shemel' tube or Shemel’ ), a lesser-known but interesting feature in some vintage or specialized radio frequency (RF) circuits, particularly in Russian or Soviet-era electronics.
It sounds like you might be referring to (sometimes spelled Shemel' tube or Shemel’ ), a lesser-known but interesting feature in some vintage or specialized radio frequency (RF) circuits, particularly in Russian or Soviet-era electronics.