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Re: [TCML] Odd VTTC Streamer Behavior
When I tried using a an 8kV rated mica transmitting cap
with a 6kVAC power supply, the transmitting cap failed.
So that may give some idea of what voltage ratios can
be withstood in a VTTC. Of course each VTTC maybe
slightly different, etc.
For the other original issue... the problems over
105 to 120V:
Another possibility is that your staccato board may be
being affected by the RF. That may be disrupting its
operation at the highest powers. Better grounding
or bypassing of the staccato power supply may help
if that's the problem. I had plenty of those problems
when I first was perfecting the staccato concept.
John
-----Original Message-----
From: Phillip Slawinski <pslawinski@xxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Tue, 21 Oct 2008 8:08 am
Subject: Re: [TCML] Odd VTTC Streamer Behavior
I'm running a 2nF 12kV Mica transmitting cap. As I can recall the coil
has
always misbehaved above 105-120V. The streamers still have that
thudding,
but it's snappier like you said. Of course this is in stacatto mode,
and
I've tried adjusting the controller to no avail. I did sharpen my
breakout
point which helped a considerable amount, but I'm still two and a half
inches from where I was before. [That's a 7.35% decrease, which is
statistically signifigant.] I think the lackluster performance can be
pinned on the changes I made to the primary. When I was getting 34"
hits
consistently I had unraveled my 28 turn primary by a about five turns,
but I
did not remove the extra wire, I had it coiled hanging over the side of
the
VTTC enclosure. When I decided to tidy this up I removed a little of
the
wire, wrapped the rest around the form, glued it in place, and then
added
taps.
I sure hope my tank cap is not going bad, the last thing I need is
another
stain on the carpet.
On Mon, Oct 20, 2008 at 22:50, Dr. John W. Gudenas
<comsciprof@xxxxxxxxxxxxx
wrote:
Phillip
I ran into a problem like this and it was associated with the tank
capacitor starting to fail.
If I increased the voltage after about 95volts the streamers got
smaller
and "snarpy".
I wasn't running a staccato controller so like John F. said something
was
going bad.
While not a good idea, in complete frustration, I cranked up the
variac and
waited for something to fail.
I exploded a mica transmitting cap. Nasty mess. If you are running an
MMC,
after a run see if they are getting warm.
All it takes is one bad cap in an MMC. If your coil was running
great,
then it started to run not so great and you didn't change a thing,
you likely have a failing component or poor connection somewhere. In
my
case it was the tank cap.
Yours could be different. Good Luck
John
John W. Gudenas, Ph.D.
Professor of Computer Science
On Oct 20, 2008, at 9:28 PM, Phillip Slawinski wrote:
I ran it for quite a while today, and I think I made some progress
towards
getting back to where it used to be. It's hitting 31.5", and it's
making
a
thudding sound while doing so. It does this while running just shy
of
105V. If I push it up to 115V or higher the sparks start to make a
cracking
sound in addition the the thudding. It's also at this point that the
sparks
start to branch and become shorter.
I tried lowering grid resistance and it only results in shorter
sparks,
and
only marginally at that. I'm a little wary to lower the resistance
since
the accident that marked the end of the good performance I was
getting
from
the coil. I kept turning down the resistance until the secondary
flashed
through the silicone sealant and ruined my grid coil. Of course,
this was
an extreme case, and foolish at that.
I did move the grid coil down to increase the coupling a little and
that
seemed to help.
On Mon, Oct 20, 2008 at 21:03, <futuret@xxxxxxx> wrote:
The throaty popping sound may be a "bad" sound meaning
the coil is not running just right. Some component may be
failing. Or the staccato controller timing may have changed
in some way. The solid thud sound is good, other types
of sounds can be bad. Is it a raspy sound? If so that's
a sure sign something isn't right. Maybe from the high
power operation of the tubes, they became damaged.
Or arcing may have been occuring in the tubes which
can make a popping sound. You can try reducing the
grid resistance to see if it helps. That tends to keep
the voltages in the tube lower and may help. But it
will make the tubes run hotter of course. But it may
be helpful just as a quick test to get an idea of what's
happening.
John
---
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