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Re: [TCML] Tuning a coil PLEASE HELP



Andrew,

apart from tuning with a scope, we (Fritz Egli and me) have created a basic tuning step-by-step procedure:

http://twfpowerelectronics.com/~kurt/Downloads/Startup_Tuning_SG_TC.pdf

...but by scope: Herr Zapp mentioned all, what is important.

Kurt

Quarkster wrote:
Andrew -

I believe I referred you to Charles Hobson's tiscali website.

Please duplicate the EXACT test setups shown on Charles Hobson's
website. They are 100% correct AS SHOWN.

The sketch you made of your secondary resonance test setup clearly
does not match that shown on Charles' site.

Note the following:

1. The ground lead of the O'scope is NOT CONNECTED to ANYTHING.
2. The O-scope probe tip can be connected to a 10" length of wire
that should be supported so it's hanging vertically about 20" away
from the secondary, at least for initial observations.
3. I don't understand what you mean by "modulation"; there is no
"modulation" to be seen during this test.
4. To make sure that you understand the basic test setup, and that
both your o'scope and signal generator are functional, first connect
the scope probe directly to the low-voltage output of the signal
generator. The scope should display a sine wave that varies in
FREQUENCY (how close the peaks are to each other) as you vary the
signal generator's frequency. If your signal generator is of good
quality, the AMPLITUDE of the sine wave should be relatively
constant, regardless of frequency. If this is what you see,
disconnect the scope probe from the signal generator and connect per
step #2 (above).

Use the 20v output from the signal generator, and connect it directly
to the bottom winding of the secondary. The ground terminal of the
signal generator (usually black) is connected only to the ground
terminal of the frequency counter.

5. Set the signal generator to some arbitrary RF frequency (say 150
Khz), and adjust your oscilloscope controls until the scope clearly
displays a 150Khz sinewave. Adjust the amplitude so that the
peak-to-peak sinewave only takes up about 25% of the available screen
height.

6. Now SLOWLY vary the frequency control of the signal generator up
and down while carefully watching the scope. At some point, the
amplitude (the height) of the sine wave will suddenly and
DRAMATICALLY increase. You may have to re-adjust the gain on the
oscilloscope to see tha maximum height. Once you have found the
maximum amplitude of the sine wave, you have found the secondary's
resonant frequency.

7. I wasn't able to get your sketch of your primary resonance test
setup to display properly, so I don't know what your setup looks
like, but again, simply duplicate the setup shown on the tiscali
site. Do not add any other connections, etc.

Go back and perform steps #1 through #6, above, and let us know what
you find.

Regards,
Herr zapp

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