Dave,
If you're using the voltage doubler (level shifter), then you should
get 16" sparks like Steve got. Does the plate of the tube get dull
red if it runs awhile? This might be seen more easily in a dark room.
If the plate gets red then it means the tube at least is capable of
strong emission. Even without the doubler it should produce 11"
sparks. However the coil will need to be tuned differently for
high power vs. low power operation to adjust for the
capacitance provided by the spark length. Is the 810 tube known
to be strong and good? A weak tube will give weak sparks, and
the plate will never get red (or probably won't). If you used JavaTC
or some other program to tune the coil, you may need to use a 50%
larger capacitor than the program suggests to adjust for the
capacitance of the spark. I think JavaTC might have a feature
that takes spark capacitance into effect (I forget). If it does then
that can be used. But it still might need to be tuned a little
differently. Also Steve might be using a step up type variac
which can provide up to 140 VAC to the coil. That makes a
large difference in spark length compared to using just 120 VAC.
An easy way to check the tuning is to install different sized
toroids (or no toroid), and see if the sparks get weaker or
stronger. Here's my website where I show a smaller VTTC project.
https://sites.google.com/site/jfuturet/home
John
-----Original Message-----
From: David <zipo@xxxxxxxxxxx>
To: tesla <tesla@xxxxxxxxxx>
Sent: Thu, Dec 14, 2017 3:54 pm
Subject: [TCML] 810 tube coil
Hello everyone - I have completed my first tube coil using a 810 triode
based on Steve ward's 810 coil outlined here,
http://www.stevehv.4hv.org/VTTC4.htm
I've almost exactly copied his design but with mica transmitting caps.
I've been working with trying to tune primary turns and adjusting grid
coil height and turns and have been getting ~4" sparks from the breakout
point, I would have expected more.
I'm not using a staccato yet but how much should I expect from a coil
like this at 60Hz?
Thanks
Dave
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