Drag onto the page to add a tube tetrode with directly or indirectly heated cathode.
Tube tetrode (directly/indirectly heated cathode).
Tube pentode with directly or indirectly heated cathode.
Drag onto the page to add a tube tetrode with directly or indirectly heated cathode.
Tube tetrode (directly/indirectly heated cathode).
Tube pentode with directly or indirectly heated cathode.