hexode

For example, the 2F21 is not an actual hexode, but a pattern generating monoscope tube.

The hexode (six-electrode) was actually developed after the heptode or pentagrid.

Various alternatives such as using a combination of a triode with a hexode and even an octode have been used for this purpose.

The hexode contains two such grids, one for a received signal and one for the signal from a local oscillator.

This 470kHz signal is selected from the mess at the hexode anode by means of a tuned circuit which is one part of a transformer, T1.

Other tubes with multiple grids beside the pentode, such as the hexode and pentagrid converter tube, have been be used to make similar negative transconductance oscillators.

H Hexode or Heptode (of the Hexode type)

The same result was achieved historically by the pentagrid converter or a Triode and Hexode in a single tube, but can be implemented in transistor radios economically by a single transistor functioning as a self-oscillating mixer.

In order to distinguish between the two versions of the heptode, manufacturers data often describes them as 'heptode of the hexode type' for a heptode without a suppressor grid, and a 'heptode of the octode type', where a suppressor grid is present.