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Re: [TCML] 810 tube coil

John I can't thank you enough for your very insightful input - I tried to compensate for the small dimensional differences and java TC confirmed this. After all that you've said throughout this chain of emails, I should be in the ballpark and it is my gut feeling that my bargain mica tank cap may be bad at high voltage. It may check fine with my fluke mm, but it just does not work at high voltage. Anybody got a .001 10kv cap for sale? I'm too close for it not to work and not respond to tuning.

Thanks again

On 12/15/2017 6:49 PM, Futuret via Tesla wrote:

Let me say first of all that you do nice work!  Very impressive construction and design!
I looked at Steve's website again and even though it says the coil has 36 turns on the
primary, I count only 28 or so.  Of course since you're using thicker wire then more turns
would be needed for the same inductance.  For my VTTC's I usually use 28awg magnet
wire on a 3" by 11.25" winding for the secondary, and 23.5 turns (I think) of 12 gauge
stranded wire with thin PVC insulation for the primary (winding height is 3.25" if
I remember correctly).  I think I used 0.015 uF for the
tank capacitance.  That's with a 6" toroid.  I give these specs so you can put them
into JavaTC to see how much lower the primary is tuned compared to the secondary,
and see if yours has a similar frequency ratio.  That might be helpful for getting
some idea about the tuning.  Assuming that all your components are good, and
that the coil is wired up correctly, I suspect a tuning issue.  To tune my coils,
I like to keep the primary inductance fixed, and I vary the capacitance.  I do
this my mixing and matching various small capacitors.  I also use an air variable
capacitor in an oil bath in conjunction.  This lets me tune things very precisely.
There will be a range over which spark length will remain the same, but the
plate redness will dip at a certain tune point.  I then measure the C of the
capacitance array, and I then replace it with a fixed capacitor of the proper


-----Original Message-----
From: David <zipo@xxxxxxxxxxx>
To: tesla <tesla@xxxxxxxxxx>
Sent: Fri, Dec 15, 2017 5:00 pm
Subject: Re: [TCML] 810 tube coil

Hello everyone - Here are some Youtubes of this coil. My first youtubes so don't expect a lot. I had to brake it up in to two parts, a walk around showing construction and parts and then an operation vid to show how it behaves.https://youtu.be/3BLKL2aiD9Uhttps://youtu.be/GVC9M_uyN1wOn 12/14/2017 9:30 PM, David wrote:> 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 compo
  nent 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>> t
  he 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>> Sub
  ject: [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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