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Re: Frequency Splitting (Was: Tc first start)

Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>

After coeff. of coupling increases past it's "critical value" the single resonant frequency of the secondary begins to split apart into two separate frequencies. This means the HV is not achieved at the very top of the coil but at some point lower in the sec windings which causes flashovers and racing sparks. As an example, a typical 4 inch dia. sec coil should be elevated above the primary coil (flat spiral) by 2 inches. Larger coils require even more elevation for best performance. You can experiment by using small blocks of wood to elevate your sec coil in 1/2 inch increments until best output spark is achieved. Using Bob Svangren's (ref TCBA Newsletters) segmented HV sparkgap provides excellent measurement of these small increases that might not be noticeable to the human eye.

An excellent description of this is in the ARRL Radio Amateur's Handbook available in any local library. Study this in detail.

Dr. Resonance

Dr. Res,

What is frequency splitting as you mentioned below?
Ne term to me...


--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>
> Most coils only produce short sparks on fire-up.
> Don't get
> discouraged! This is normal!!
> Using a small wire taped to your toroid you can
> check the distance to
> a ground stand to see the max spark distance.
> Next, the tuning process begins.  You should always
> start with a
> "scrap wire" primary of 20-25 turns so you can
> investigate a wide
> range of primary inductance to bring your system
> into
> resonance.  Start at 3 turns out and keep moving the
> tap out as you
> check each turn for "best resonance point".
> While doing tuning, keep your total sparkgap tight,
> usually around
> 0.100 inches.  This will prevent high outputs which
> could damage your
> secondary coil if it's out of resonance with the
> primary coil.
> Also, be sure to never exceed 30-35% on your variac
> setting.  Again,
> keep this low until you get your primary in
> resonance with your
> secondary.  The best resonance point at these tight
> sparkgap and
> variac settings may only produce a spark 3-5 inches
> long.  This is normal.
> After finding the proper primary number of turns for
> resonance, now
> you can open up the sparkgap total setting to 0.180
> or 0.200 inches
> max setting. Then you can run the variac up to a
> higher level, ie, up
> to 100% and keep moving your groundstand back to see
> the longest
> striking distance.
> After the above tuning procedures you will be
> hitting longer sparks,
> and at this point you can replace the scrap wire
> primary with a #6
> bare copper wire primary (like Home Depot #6 AWG
> ground wire) held in
> place with plastic holders.
> If your coil has a sec. coil of more than 4 inches
> dia. then a flat
> spiral primary is always the best setup.  Using
> angle primaries can
> produce overcoupling and frequency splitting which
> leads to serious
> problems causing sec coil damage.
> Set up your scrap wire primary and let us know how
> it's
> working.  also, specs on what you have would be
> helpful.
> Dr. Resonance
> ----- Original Message ----- From: "Tesla list"
> <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Monday, February 13, 2006 10:05 AM
> Subject: Tc first start
> >Original poster: "Adriano Mollica"
> <adriano.mollica@xxxxxxxxxxx>
> >
> >Hello to everyone,
> >
> >this week end i did the first start to the tesla
> coil i built.
> >
> >Of course it doen't work...
> >
> >too b