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Re: "tapping" the primary
First, when bulding the primary, add extra turns in the event you need to tap
outward (e.g. increase inductance). Another good tip that has been used is to
build a mock-up primary out of a thick wire using the mock-up to ensure the
coil tunes to the number of turns the program you used identified.
I connect one leg to my primary (flat, soft copper tubing) at the inner turn
leaving it there. The second leg is the one I use to tune. I used a simple
capper strap - formed it around the primary tubing - drilled two holes at each
end - use a washer, screw, and nut to connect to the second leg. The copper
strap fits perfectly around the primary and little chance of turn to turn
arcing at the tap point. The holes were drilled so that when in place, it
provides a nice tight fit without stretching the strap. Obvisouly, you
disconnect the tap, move it, reconnect it during turning.
To tune (roughest procedure), simply use a ground target parallel to the top
load. Tune for the longest spark by moving the target further away and
retuning. This method will work but it is rough. It is important to keep all
the running variables constant during this procedure such as input voltage,
power, spark gap temp, etc..
There are other methods using signal generators. I haven't used this method to
date, but maybe someone will post it for you or you can check the archives at
One other point. Whenever you change a demension, cap size, top load, etc.. you
need to retune as these and other variables change the tune point.
Tesla list wrote:
> Original poster: EMG8714-at-aol-dot-com
> hi everyone,
> I have a question regarding how to put power through, or "tap" the primary
> having done my calculations for the primary, and finding out it needs to be
> tapped at around turn 6 or 7, I was wondering just what the right way to tap
> it is.
> I am new at building coils, so I don't know a whole lot about their
> construction. If anyone has the slightest idea what i'm talking about, and
> knows how to, please tell me the correct way to tap the primary.
> ---eric gendron---