DM70 in Reverse mode operation

 Fellow Radiophiles:

The following curves compare the operation of the DM70 in normal mode with reverse mode.

In normal mode, the control voltage input is applied to the grid and the current output is at the plate. In reverse mode, the control voltage input is applied to the grid and the current output is at the grid.

The principal difference between these modes of opeartion is that normal mode has a comparatively high output impedance with higher transconductance and higher mu and requires relatively high supply voltage at the ouput plate. Reverse mode operation yields much higher current flow at the grid output with low supply voltages, but at the expense of much lower gm and much lower mu which is on the order of the inverse of normal mode mu.

This measurement provides data to explore the possiblity of operation in reverse mode in a low voltage AM transmitter operating with a 9V battery.  Follow the link for the result.

Regards,

-Joe

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