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Re: [TCML] 810 tube coil

John thanks - 16" sparks from an 810, wow I would be happy with 11. I am using a level shiftier w/ 2uF and the plate can get very red if I push it. I have a milliamp meter on the  ground side and it easy gets to 300ma or more using a 140v variac. The tube can get very red if I push it to 250 to 300ma or more and that's at ~50% on the variac. I've ajusted primary turns from 36 to 44 with very little change. I've adjusted the height of the grid coil with little change tho it seem to work better the higher it is. Does the grid coil couple with the primary coil or the secondary? Steve was using a Staccato controller and I'm not yet. I'm using component values and set up as outline on Steve's page. For spark capacitance on Java TC I add a small diameter cylindrical topload by the length of spark in addition to the toroid and it seems to be pretty close. For tube coils is the tank suppose to match the secondary res frequency with spark and topload? 

Dave

On 12/14/2017 8:22 PM, Futuret via Tesla wrote:

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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