Tubes with means for concentrating the electron stream, e.g. beam tetrode

Full Title

Vacuum tubes (H01J25/00, H01J31/00 - H01J40/00, H01J43/00, H01J47/00, H01J49/00 take precedence; details of vacuum tubes H01J19/00) > Tubes with a single discharge path > having electrostatic control means only > with one or more immovable internal control electrodes, e.g. triode, pentode, octode > Tubes with means for concentrating the electron stream, e.g. beam tetrode