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Re: [TCML] Odd VTTC Streamer Behavior

I use a 12kv 2nF mica, I'd be surprised if I'm feeding it more than
6k.  That leaves room for 100 percent voltage reversal.

As to the interference problem I suppose that could be the problem.  I
used to have more problems with interference.  The controller would
cease to keep the ground switched off after a certain voltage was
reached.  What I mean is that the coil would start operating at 60

To solve this I enclosed the controller and power supply in an
aluminum box which is grounded.  I have the ground from the triac
running in RG-8 to prevent voltage from being induced in the cable.
This seems to have eliminated any interference problems with the
controller, but I could be wrong.

On 21/10/2008, futuret@xxxxxxx <futuret@xxxxxxx> wrote:
> 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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