Re: Tune Up- FAQ?

Subject:  Re: Tune Up- FAQ?
  Date: Sun, 15 Jun 1997 18:11:59 -0400
  From: "Thomas McGahee" <tom_mcgahee-at-sigmais-dot-com>
    To: "Tesla List" <tesla-at-pupman-dot-com>

> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-poodle.pupman-dot-com
> Subject: Tune Up- FAQ?
> Date: Sunday, June 15, 1997 5:48 PM
> Subject:  Tune Up- FAQ?
>   Date:   Sun, 15 Jun 1997 16:29:52 +0000
>   From:   jmonty-at-mail.sat-dot-net
>     To:   Tesla List <tesla-at-pupman-dot-com>
> Is there an faq that instructs the novice with a new coil how to
> it up and optimize it. Inquiring minds want to know..
> Thanks,
> Jeff  Montgomery
> Palestine, Texas

There is a Tesla-2 list that is set up to help beginners.
Mike Hammer just posted a piece on this exact topic.
So I am copying it to the Tesla list in the hopes that it helps.

Fr. Tom McGahee

From: Mike Hammer <mhammer-at-misslink-dot-net>
Date: Sat, 14 Jun 1997 14:51:40 -0500
Subject: Tesla coil tuning

Hello all,
Several people have asked me via email and on the
IRC Tesla channel about how to go about tuning
a coil and the steps to take.

So I thought I would share some info on the subject with
the list.

Once a Tesla coil is set up and ready to fire, certain steps
should be taken before power is applied. Don't expect to throw
full power into a new coil or a newly rearranged system. If you do
you may damage components. The coil must be brought into tune
and up to full power gradually.

The use of a variac is highly recommended for controlling
the input voltage to whatever step up transformer you
may be using. (neon, obit) Never throw full power to a coil
until you are sure the system is in proper tune.

Set the primary circuit up first. Double check all of your
connections. Run your grounds and double check those. Never take
any connection for granted. Set the secondary into the
primary and attach the RF ground. Use a small discharge terminal
at first. A small spherical terminal works well at this point.
A smaller terminal will break down and produce spark
at a lower power level than a larger terminal. This allows
you to search for the proper tune with less stress placed on
components. If you dont have a smaller terminal and only have
a large toroid place a point discharger on the toroid. Sparks
will easily break out from such a point. Often times a well placed
thumbtack will work well.

I can't overemphasize this point. Don't run a lot of gap.
This will limit the peak voltages in the primary to low
levels while things are out of tune.
As things are brought closer to resonance the gap can be opened
a little at a time to increase the primary energy level.

Apply a bit of power until the spark gap fires. If no spark
breakout is seen from the discharge terminal don't worry. Use a
flourescent bulb as an indicator. As the coil gets closer to
the farther away and brighter the bulb will glow. Turn off the coil
and move the tap connection on the primary coil a half turn and
check the bulb brightness. Then move it a full turn in the
opposite direction and note the brightness of the bulb again.
This way you can determine the direction the tap needs to be
moved to locate the proper tune.

Open the main and safety gaps up in steps. Apply the same voltage
input (low power) and check for discharge. Once spark has begun
to break out of the discharge terminal use it as a visual
indicator of tune.

If you find the best tune point is with very few primary
turns then your primary cap is too large. Adding a larger toroid
to your secondary will lower its resonant frequency and allow
you to tap in more primary turns also.

If you get tuned all the way out to your last primary turn
and you still havnt found the resonant point then your primary
cap may be too small or your toroid too large.
This often happens with beginner coils wound with far too
many turns of small guage wire. The large number of secondary turns
causes the secondary resonant frequency to be very low and beyond the
of your primary circuit. Cutting down the secondary to no more than
turns will help here.

A system in proper tune should not break down the safety gap often.
safety gap once set properly should not be too active. Once the coil
is in good tune the safety gap electrodes may be opened to the point
where it only fires occasionally.

If your safety gap is firing continuously then you may be out of tune
or you may be running too wide a main gap. Try closing down your main
slightly and retuning for best output.

Hope this is helpful.

As always comments, criticism and large sums of money welcome.


Mike Hammer

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