[Donald Ennis]

I'm new to this and just figuring out how to use newsgroups so please bear
with me. I'm in the process of testing a large quantity of 6EJ7 vacuum
tubes. I have access to power supplies, scopes, signal/pulse generators and
many other labe grade instruments. This is what I'm attempting to do. I
have been varying the control grid voltage from -2 volts to -3 volts while
keeping screen grid at 200 volts. Supply voltage (B+) is 350 vice. Plate
resistor is 15K and Grid is coupled to ground with 10K resistor. According
to the curves for pate current vs. control grid volts I should be getting 10
ma plate current @ 200
volts plate voltage with -2.5 volts at control grid. What I'm getting is
about 187 plate volts and 16 to 17 ma. plate current at this point. On some
of the tubes the current goes quite high and the plate voltage drops to
around 120 vdc with the control grid @ -2vdc. When I change the control
grid voltage to -3 vdc the plate current sometimes drops off sharply to ua
and the plate voltage climbs to around 260 and 280 vdc (I'm doing this from
memory). To me it appears that the tubes are bad but I'm not quite sure how
to interpret the measurements. I have been told that these tubes have a
below average output and I'm trying to verify this. Any thoughts or ideas
would be welcome. I have posted in some other newsgroups and have received
some good replies but this group seems more oriented towards vacuum tube
technology. Thanks for any help.
Don