Re: A few problems..

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "M G" <gt4awd@xxxxxxxxx>

The max output I get right now is fine for me, but it would be nice 
to get around 20" streamers. For a first coil it turned out good 
enough. Just a few more things I need to do and it will be complete. 
My top priority right now is to finish building a portable base that 
holds all the components. If you look at the pictures of the complete 
setup you can see the capacitor/sparkgap board and terry filter board 
are just sitting slightly above the ground.

The primary might be close to tuned, but due to the amount of 
imperfections on my primary coil I was told finding the exact (1/4?) 
resonant tap point would be difficult because a programmed 
calculation, for instance using TeslaMap, would be off. For now I 
have been using TeslaMap5. It calculates the tap point to be right 
before the start of turn nine. So its possible I am tapped slightly 
over resonant right now, but where I am tapped seems to work best.

I checked where the secondary bottom winding sits compaired to the 
primary and it seems to be no more than 2" below the top primary 
turn. I really cannot move the secondary up any more without finding 
a new bolt that is longer, and remaking the bottom end cap. The bolt 
on the end cap goes through a hole on the primary support and on its 
end is placed the ground connection and a nut which holds the 
secondary in place. It only has less than half an inch left that 
could be moved up and the nut screwed on.

Matt G.

------------------------------------------
Original poster: "Barton B. Anderson"

Hi Matt,

Thanks for sharing the basic specs at the bottom of your post. Don't
be depressed if you don't reach the 28" spark length. Feel real good
if you get close 20" to 22"! Your coil is large enough to run a 12/60
NST if you feel up to it. The specs indicate your coupling is too
high (which explains your periodic racing sparks). Adjust your
secondary so the bottom turn is 1.5" below the center line of the
primary's top turn (due to your particular . This should result in a
coupling of 0.12. I would probably do that before winding a new primary.

Your max sparklength expected is 24" with your particular NST (not
28"). Yes, only 4", but calc's I use don't show 28", even on a good
day. Once you adjust the secondary, you will likely only notice that
racing sparks are not occurring and no change to spark length. This
is normal. Now, work on you spark gap. Rebuild it if necessary. This
is the obvious component for losses and is where the best increase in
sparklength is to be realized. Much "power" is lost in the gap.
Minimize the power lost at the gap and you will increase the power
available for output sparks. This is not always easy, but it is
definitely a very important arena to do battle in (up to 50% losses
in the gap on average). Any increase there in efficiency goes a long
way with spark lengths. Anyone who has coiled long enough realizes
the importance of a "good" spark gap. It can make or break a coil.

Take care,
Bart

---------------------------------------------
Original poster: Ed Phillips

Are you sure the primary is tuned correctly? Doesn't look like
enough turns to me but I haven't tried to run the calculations.

Ed

---------------------------------------------
>Original poster: "M G"
>
>Hi everyone,
>
>I finished my first coil a little more than a week ago. A 4" spark
>gap coil, using a 9kv 30ma NST, and eleven 2kv .15mfd CD capacitors
>in series. For past week or so I have been adjusting certain parts
>of the coil to get better output. My recent changes include making a
>tap for capacitor eleven, which helped increase secondary streamer
>output by some. Raising the secondary coil up more to prevent
>overcoupling racing arc's. Still seems to happen on full power runs.
>
>The secondary appears have not received any damage from the
>problems, but I will probably add more polyurethane coats just in
>case. Some may remember that my primary is at too high an angle, 55
>degree's. Is it time to just scrap the primary and make a flat
>spiral or can I get good coupling just by raising the secondary up
>more? So far the best output of the coil is only around 12-14",
>which is no where near the 28" that should be possible using a 9kv
>30ma PSU. The coil uses a "Terry filter" setup as shown in the
>standard filter schematics. I was wondering if the filter degrades
>overall performance some in trade for less stress on the NST?
>
>The toroidal topload, 4"x8.5", is made from aluminum ducting, and
>covered in aluminum tape in an attempt to smooth out the sharp
>points some. Secondary end is connected to topload by end of the
>wire. I have yet to make the secondary top end cap. Secondary bottom
>ground, with end cap, is made with end wire wrapped around solid
>brass bolt. I would appriciate ANY suggestions for improving the
>coil output. Max output is around 10" with occasional 12-14" air stramers.
>
>All of the images I have taken so far of the coil can be viewed on
>my imageshack public page.
>Link: http://profile.imageshack.us/user/gt4awd/
>I would just put links if there was not so many images.
>
>Here are some coil specs I did not mention.
>
>Secondary: 4.20"x20.25" using 26AWG single build magnet wire on 
thin wall pvc.
>
>Primary: 55 degree angle using 10AWG non-insulated solid copper
>wire. Tapped at turn 9.7 with a total of 11 turns. Inside diameter
>is nearly 7", outside diameter 13", height of 4.5", and primary turn
>spacing of about 1/2". Both connections leading to primary are 
nearly 2' long.
>
>Wire: Primary circuit wire and ground wire using 12AWG insulated
>solid copper wire.
>
>Filtering: Standard "Terry Filter" for high voltage end, and a 2x10
>amp CD RFI filter for mains line.
>
>Ground length: Coil support stands about 2' above ground level.
>Ground wire has a total length of around 15'.
>
>I might be missing some important information. Let me know if I am.
>
>Thanks,
>Matt G.

----------
Create and Share your own Video Clip Playlist in minutes at Lycos MIX 
(<http://mix.lycos.com/?if_Event=MAILmixtagline>http://mix.lycos.com)