Charles (and others),

Thanks for your reply.  Can the group check my head?  I want to know I
understand what is going on here.

>From the datasheet.  IN-14's strike no lower than 170V.  They are not
to exceed 200V.  Average current is 2ma.

Based on this data, I adjusted my supply to put out 180v.  I'm firing
up a IN-14 tube with a 20K resistor.  The voltage drop is 40v across
the R, so the tube is seeing 140v.  Now assuming R = (Vp - Vt) / Ic ,
I get:

R = (180v - 140v) / .002a
This gives R as 20k ohm.

Obviously,  Ic = (Vp-Vt) / R shows current is (180v-140v) / 20000 Ohm
(which here is .002A or 2ma).

Based on my observations and what I am doing as stated above, I think
it's safe to assume I am not abusing my tubes?

Also, I dont have an instrument that is fast enough can measure the
striking voltage prior to the tube lighting but I assume in my
scenario, I could 180v at the tube prior to ionization.  Correct?

Now as far as multiplexing goes, exceeding the max allowed current
(2.0ma) to the tune of 7-13 ma during the pulse, is "ok" because the
duty cycle is so short.  So in essence, we are over-driving the tubes
(during the pulse) which is unhealthy, but we justify the tube life by
saying the tubes are only being "abused" for a very short time over
all?  The duty cycle balances it out basically?  If this is the case,
why do people say muxing extends tube life?  Are we "resting" for a
longer overall period of time than we are abusing?

I'm thinking direct drive is looking better and better.  ;)  At least
it's easier to feel good about not abusing your tubes.

Also...  I'm getting the bluish hue to my tubes.  I assume I have one
of the more modern tubes with a trace amount of mercury for
longevity?  I didn't think *any* IN-14's were made that way.

-Ryan

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