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Re: [TCML] 810 tube coil


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 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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