Diode, directly heated

Diode, indirectly heated

Diode, envelope, direct. heated

Diode, envelope, indirect. heated

Triode, directly heated

Triode, indirectly heated

Triode, envelope, direct. heated

Triode, envelope, indirect. heated

Tetrode, directly heated

Tetrode, indirectly heated

Tetrode, envelope, direct. heated

Tetrode, envelope, indirect. heated

Pentode, directly heated

Pentode, indirectly heated, external connection

Pentode, indirectly heated, internal connection

Pentode, envelope, direct. heated

Pentode, envelope, indirect. heated, external connection

Pentode, envelope, indirect. heated, internal connection

Diode, directly heated 2

Diode, indirectly heated 2

Diode, envelope, direct. heated 2

Diode, envelope, indirect. heated 2

Triode, directly heated 2

Triode, indirectly heated 2

Triode, envelope, direct. heated 2

Triode, envelope, indirect. heated 2

Tetrode, directly heated 2

Tetrode, indirectly heated 2

Tetrode, envelope, direct. heated 2

Tetrode, envelope, indirect. heated 2

Pentode, directly heated 2

Pentode, indirectly heated, external connection 2

Pentode, indirectly heated, internal connection 2

Pentode, envelope, direct. heated 2

Pentode, envelope, indirect. heated, external connection 2

Pentode, envelope, indirect. heated, internal connection 2
