"John Larkin" wrote in message
...
Gm/Co was a popular figure of merit for tubes used in video amps and
oscilloscopes. They took a hockey-stick turn upward when frame-grid
tubes were invented, just before semiconductors took over.

7KY6 has four times the transconductance of 2N3819, and plenty more voltage
and power capacity.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms