[TCML] HELP Oscilloscope coil tuning! BIG TOPIC!

[Andrew Robinson]

Ok, so I just got back from the lab on campus. I was playing with the 
new digital scopes which I am going to be able to use to tune the new 
coil im building. Ya Universities! Heres the thing... I'm no stranger to 
coiling, but a newbie when it comes to using the scope. Can someone very 
carefully explain process to me... That is, correct what ever it is that 
im doing wrong. First off visit this link on my server to see a diagram 
I made real quick in paint to show you my setup.

http://host.atomiklan.com/tesla/scope1.png            (Note: The 
frequency on the multimeter means nothing, just a visual aid)

Ok so in this first image, im attempting to obtain the operating 
frequency of the secondary coil with toroid. Correct me if im wrong, but 
the toroid, secondary coil, air, and ground acts like a inductor 
capacitor circuit hence the frequency. The toroid forms a capacitor with 
earth using air as a dielectric. Is it possible to measure the frequency 
of the coil without the toroid? Im assuming yes... but pointless. Ok so 
to make replies simple and easy i'll number all my questions at the 
bottom of this page.

Ok so back to the setup. Here are my understood steps to tune the coil...

1:    I should use the tesla geometry formulas for an inductor and 
topload to get the general area of the frequency of the secondary and 
toroid so I dont have to sweep the entire range of signal generator.
2:    Attach the signal generator to the bottom of secondary.
3:   Turn on below area of expected resonance.
4.   Hang oscilloscope probe near secondary coil.
5.   Raise frequency on signal generator and watch scope till the 
amplitude of sine wave maxes. At this point this is the frequency of 
coil. If you pass this by continuing to raise frequency, the sine wave 
amplitude should drop again till you reach another resonance point.
6.   Read the frequency where sine wave was max on the multimeter. (The 
multimeter was only in setup to get a digital readout of analog signal 
generator.)

Ok, now that we have the secondary coils resonate frequency, its time 
for the primary tank circuit.

Diagram: http://host.atomiklan.com/tesla/scope2.png             (Note: 
The frequency on the multimeter means nothing, just a visual aid)

1:   Disconnect the transformer and any filiters. You should only have 
the sparkgap, capacitor, and primary in the circuit.
2:   Bridge the sparkgap.
3:   Wire sparkgap, capacitor, and primary in series like normal.
4:   Attach oscilloscope probe to one end of primary and im assuming the 
ground of probe to tap point??? You should use a 10K ohm resistor on 
probe in this setup.
5:   Attach signal generator in same manner. One to end of primary, and 
other end to tap point. Then adjust the tap point on primary till you 
achieve the exact same frequency as above.

Ok so my questions.

1. Can the secondary frequency be found without the toroid? Or is this 
pointless?

2. When getting secondary frequency, do i leave the alligator clip on 
probe attached to ground, or nothing?

3. What settings should I set on the signal generator as far as strength?

4. When I tried testing this setup today with a test coil, when i varied 
the frequency, the amplitude went up but never peaked at the "correct 
frequency". It would just keep increasing no matter what setting I set 
it on. What am I doing wrong here?

5: Am I missing something as far as using the scope correctly?

6. In regards to tuning the primary, is my setup correct as far as where 
to connect everything?

7. Do I use the 10K built into probe or do i need another resistor?

8. The scope probe goes on one end of primary with... where/what does 
the other connect to? Ground of probe to other end of primary? Other end 
of primary into another port on scope?

Thanks everyone for all your help!

Hopefully this will clear up any confusion using scopes not only for me 
but others as well.

Thanks,
Andrew Robinson