"Martin H. Eastburn" wrote in message
...
If the Grid is near zero and you drive over into the + side - the Grid
pre-accelerates boiling electrons gathering on the hot cathode - IIRC
thorium enhanced
book still in shelf.

811 is an example of a directly heated thoriated tungsten cathode; 6L6 uses
an indirectly heated unipotential oxide coated cathode. Also, red plates
are simply too much dissipation, on a 6L6 at say, 400V screen and plate,
you'll get glowing around oh, -20Vg.

I don't recommend anyone touch any hot tube if it is half the length of a
cig lighter.
More than that, and the wattage can far exceed the capacity of your skin
to self cool.
a.k.a. burn.

And that rule of thumb (and fingers, and hands, and anything else that might
contact a hot tube doesn't apply at all to Hept'AU7:
http://webpages.charter.net/dawill/I...tAU7_Front.jpg
For all that size, weight and heat it only puts out 7W. But that's plenty
(unless I'm listening to Metallica, anyway). :-)

Tim

--
"That's for the courts to decide." - Homer Simpson
Website @ http://webpages.charter.net/dawill/tmoranwms