| David Vinch | Saturday, 8th July 2006 3:58am - No.91 |
| The 1.8nf 50v capacitor seems to be a problem for sourcing here. Do you have an alternative? |
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| RMCybernetics | Saturday, 8th July 2006 5:56am - No.92 |
The value of this component does not really have to be exact. Use the closest value (capacitance) you have available and it should work fine. The only real difference will be in the accuracy of the printout for the frequency dial. To use this device it is not essential to know the exact frequency ayway.
This capacitor is charged and discharged by the 555 timer to produce the output frequencies. If you replace it with a larger capacitance then your output frequencies will be lower. Replace it with a smaller capacitance and the frequency will be higher. |
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| Chris F | Thursday, 20th July 2006 6:11pm - No.103 |
I have found that using two Radio Shack 0.001 uf (1 nf) capacitors in parrallel works pretty well. Their value is actually more like 0.0009 uf or 0.9something nf apiece. Your values may vary. Putting them in parallel gets you really close 1.8 nf. BTW: I measured it with a LCR meter to check this.
Also... 2 questions:
1) How do I increase the frequency range? Do I make the capacitor smaller. I measured that mine had a range of 20 kHz to 415 kHz. I would like it to be more in the range of 100 kHz to 1.5 MHz or so. I have been working with rather small coils and they resonate at higher frequencies.
2) Is this an Astable 555 Circuit? If it is why is the discharge pin not hooked up?
Thanks in advance,
Chris F. |
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| RMCybernetics | Thursday, 20th July 2006 6:11pm - No.104 |
One method for increasing the frequency range of a 555 circuit is to add a switch which allows you to select your timing capacitor. An example of this can be seen on the DIY PWM Signal Generator page. The 555 timer may generate frequencies of up to 1MHz, but there can often be instabilities in the signal at the high end.
The discharge pin is not hooked up as the circuit is configured to respond to the inductive or LC nature of the coils. The discharging of the timing capacitor depends upon the nature of the curcuit you are 'tuning' rather than it being directly discharged by the 555 timer.
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| Jim Paul | Sunday, 27th August 2006 5:06am - No.190 |
Will a pair of diodes wired in oposite directions substitute well for the bi-colored diode?
Will increasing the capacitor by a factor of 10 reduce the frequencies by a factor of 10? |
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| RMCybernetics | Sunday, 27th August 2006 5:07pm - No.194 |
I assume you mean replace it with two LED's wired in opposite directions, which would work just fine.
If you used just diodes there would be no indicator showing tuning.
Increasing the capacitance by a factor of ten will not exactly reduce the frequencies by a factor of 10 but it may be close enough. This is because the rate at which the capacitor is charged and discharges depends on other factors too. |
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| BW | Friday, 8th September 2006 4:06pm - No.238 |
| Hello. I have built the unit..output of 96kc to 330kc. The LED has a very dim output throughout the range and then no LED wide open. What LED are you using? Have any idea why the LED cuts off? Thanks. |
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| BW | Friday, 8th September 2006 5:24pm - No.239 |
| OOPs. I had tied the chip output to C1. I fixed this and checked everything else again. Now I can't get anything to work. The circuit is now correct...C3 is 1nf. I changed the 555 and same problem exists. Tested LED...fine. There is no oscillation...output steady at about 8v. Any ideas? Thanks. |
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| RMCybernetics | Friday, 8th September 2006 8:53pm - No.242 |
Not sure about that one. Are you measuring the output at the TCT probes, or directly from the output pin of the 555?
This device was designed by Terry Fritz of hot-streamer.com. His contact email listed on his site is "terry[at]hot-streamer[dot]com" |
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| Santa ( no Bike for you ) | Monday, 25th September 2006 8:16am - No.326 |
 Tesla Tuning problem..
The tuner works very well.My coil is tuned correctly for the first time..Spark length was Maximum 17 Inches. The tuner proved that my primary coil was far from right, it would not tune any where near the secondary. Rebuilt primary, tuned, Powered up and Max Spark is now 25 Inches..A very useful tool.
A frequency counter is a very good partner for the tuner,quite a few Digital Volt Meters now have frequency counters.
Also useful for checking Bat Detector Frequencies, sonic ears etc..
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| James Howells | Thursday, 26th October 2006 10:59am - No.433 |
| I am not too sure where the test leads connect on the T.C. TESTER circuit is it pin 7 and pin 5? |
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| RMCybernetics | Thursday, 26th October 2006 10:25pm - No.435 |
| The test leads are indicated on the diagram by the two circles. One is simply connected to ground (negative battery terminal), the other is connected to the LEDs.
Pins 5 and 7 do not connect to anything. |
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| James Howells | Friday, 3rd November 2006 9:45am - No.445 |
I got the TCT working, checked it out by loose coupling to my friends Transciever and there appears to be a signal out ... and at very accurate calibration. BUT when I try it on a coil
( 22mm dia 740mm long, 0.27 mm enamelled wire, dia . approx 260 turns.
I calculate =377 micro Henry about = 223 kHz
1.344 pF ) I only get bright LED's all the time, they only dim at about 30khz which is near the end of the pot travel.
Any ideal what I am doing wrong... this is testing just the secondary coil with out any cap connected |
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| RMCybernetics | Friday, 3rd November 2006 10:25pm - No.449 |
| Maybe you could try changing the value of the timing capacitor (C3). This would allow you to tune the TCT over a different range of frequencies. The pot doen't give you a linear adjustment, so a different cap may help you adjust from a more central position. |
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| Chules | Thursday, 5th April 2007 3:11pm - No.1072 |
| Would it be possible to replace the LED with a digital ammeter for more accurate tuning? |
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| RMCybernetics | Thursday, 5th April 2007 3:58pm - No.1073 |
| Yes you could, but you would need to account for the bipolar nature of the signal if your meter is a DC one. |
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| Chules | Sunday, 15th April 2007 3:26pm - No.1164 |
| Is the purpose of C1 to convert the square wave into a sine wave or what? Thanks. |
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| RMCybernetics | Sunday, 15th April 2007 3:30pm - No.1165 |
| Its is there for DC blocking, but it will probably round the edges too. |
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| Chules | Sunday, 15th April 2007 4:31pm - No.1167 |
| Where does the DC come from that needs to be blocked? |
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| RMCybernetics | Sunday, 15th April 2007 5:06pm - No.1168 |
| The output from the 555 timer is a sequence of dc pulses. It basically allows the connected LC circuit (tesla coil) to ring properly with AC. |
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| joel | Friday, 18th May 2007 4:08pm - No.1300 |
| forgive me for asking a stupid question but with the tc tuner would the dimmest spot be resonance for both primary and secondary or is ther mathamatical equasions involved if so please explain in laimen terms. also would standard copper wire low resistance be good to use on the prototyping board? joel |
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| RMCybernetics | Friday, 18th May 2007 5:15pm - No.1301 |
The tuning instructions are in the article. Read the last 2 paragraphs.
Secondary coil and topload - brightes spot is resonant.
Primary coil and cap - dimmest spot is resonant.
I'm not sure that there is a 'standard' copper wire. This circuit uses very low currents so quite thin wires will be fine. I would guess that the standard you refer to is something around the thickness of the individual wires in a network or telephone cable. This thickness is fine.
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| joel | Saturday, 19th May 2007 1:26am - No.1305 |
| thank you very much but to sum up what you are saying dose this mean we are finding resonance individualy primary and individualy primary? i thought it worked by finding resonace of the secondary find the number on the dial keep dial still on that number and make your way through the primary to the dimmest spot so that both resonaces join .joel |
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| joel | Saturday, 19th May 2007 3:53am - No.1307 |
| with the tc tuner dose it matter if you replace the 470 ohm resistor with 471 ohm would this make a difference this is the colour band if im wrong plz correct me yellow ,purple,brown |
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| RMCybernetics | Sunday, 20th May 2007 1:28pm - No.1319 |
The TCT finds the resonant frequency of the primary or secondary circuits. This means either the combined inductance and cpacitance (LC) of the primary, or the LC of the secondary.
Yes, the simplest way to use this is to measure the f of the secondary coil and then try to adjust your secondary turns or capacitance until it also resonates at this frequency.
If the resistance is really 471 than this should make no real difference but I think you are reading the codes wrong. 471 ohms is not a standard value. The colours should read Yellow(4), Purple(7), Brown(x10).
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| Your name here Joe,Australia | Tuesday, 22nd May 2007 7:19am - No.1326 |
Dear RMC,I have three small and medium size BIPOLAR TCs with equal toploads on each end of the secondary.
They are functioning OK. However, I want to find resonant frequencies by means of DIV TC Tuner. Could you please advise how to connect the Tuner to test bipolar TC. Thank you. |
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| RMCybernetics | Tuesday, 22nd May 2007 1:29pm - No.1328 |
| If the secondary coil is centre tapped for RF ground then you would test it in the same way. Otherwise you would have to use one of the ends instead. |
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| joel | Wednesday, 23rd May 2007 2:50pm - No.1332 |
| im not sure if my device is quit working but when connected to the primary the led lights up but when connected to the secondary nothing im not sure if my toriod is not at resonace capacitance or if the circuit is just lighting the led with no square wave and i have no ossiliscope to test could you suggest a reason for this problem? |
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| RMCybernetics | Wednesday, 23rd May 2007 5:21pm - No.1333 |
The LED indicates how much current is flowing from your tuner. At resonance the reactance of your secondary will drop and allow current to flow.
If the applied fequency is not correct then the LED will not light. 555 timers come in a few flavours even thuogh they are all called a 555. Some work up to just 0.1 MHz, while others will go to 1 MHz and some even go to 2 MHz. Check the manufacturers datasheet for the 555 you have to see if it it goes high enough.
It could also be that your coil/topload combo is too small for the TCT. It will work well for large coils but smaller coils can resonate well above 1 MHz which would mean that the LED would not light up. |
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| Lloyd | Saturday, 4th August 2007 7:18am - No.1532 |
| does the cap have to be a polypropylene i am using a .001uf ceramic-disc cap, seems to work. |
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| RMCybernetics | Saturday, 4th August 2007 7:19pm - No.1534 |
| You can use any type of capacitor dielectric. |
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| Lloyd | Monday, 13th August 2007 7:16am - No.1579 |
| I have build my tuner with a 3 way switch to change out caps. and can reach freq. of 2 mhz according to my freq. counter. is there any way the make the tuner output more accurate right now im using the bicolor led. i have to wires with aligator clips coming off each of the led lights leads for expiremening. any ideas would greatly help. thanks |
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| Lloyd | Monday, 13th August 2007 7:25am - No.1580 |
| are we looking for an equal current draw and pull in the led so that both parts of the led light. if so with the use of a digital auto polar multimeter when voltage is a zero than there is equal draw and pull. but im just not sure i understand how the led read-out exactly works. |
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| Lloyd | Monday, 13th August 2007 7:46am - No.1581 |
| One more question when hooking my multimeter up to each lead of the led in ac mode lowest voltage is dimmest and highest voltage is brightest right?(it seems to be) thanks abunch for your help. Lloyd Romero |
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| RMCybernetics | Monday, 13th August 2007 3:21pm - No.1582 |
Push/Pull should be equal. There are two diodes (or bi-color LED) used so that current can flow in both directions through the probes. This is useful because when each square wave pulse hits the LC circuit it is allowed to ring.
The brightness of the LED's indicates how much current is being drawn by the load (your LC circuit). If a lot of reactance is produced by the load then the LED's will be dimmer.
To make the reading more accurate you could use a comparator. This could be set up to compare a reference voltage to the voltage you measured on the LED's. For example; if measuring an LC series circuit the comparator could be set so that it lights another LED only when the measured voltage is high enough. |
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| justin | Monday, 26th November 2007 2:27pm - No.2233 |
hello
i decided to do some studying instead of asking dumb questions lol but im confused about this one equation for universal capacitance and hoped you could help
c[f]=r[m] divided by 9x10 power of 9
i know how to do the equation but how is this relevant to the seconadry windings, it only meassures the capacitance ,do you know any equations that would be relevant to both the secondary and the toroidal capacitance?
by this i mean from the seconadry equations how do you know what surface area to use as a toroid. i hope my question isnt confusing thanks |
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| RMCybernetics | Monday, 26th November 2007 10:31pm - No.2236 |
I don't know what your equation for c=r/9E9 is about at all.
You can find info on toroid capacitance here |
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| tomson | Wednesday, 28th November 2007 1:24am - No.2244 |
| for the tesla tuner at the top would it matter what type of capacitor you use for example could i use a electrolight capacitor rather than the ones posted provided they have the same microfard rating? |
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| justin | Wednesday, 28th November 2007 12:52pm - No.2247 |
is N1 Over L1 = tO N2 Over L2
primary LC = to seconadry / toroid in frequency wise? |
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| RMCybernetics | Wednesday, 28th November 2007 2:14pm - No.2250 |
tomson,
Yes, electrolyitis are fine
justin,
Not sure what you are talking about. I assume N1 and N2 refer to numbers of turns, but without any reference for context the formula is useless. If you want a good answer your question needs to contain more detail. |
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| justin | Wednesday, 28th November 2007 11:17pm - No.2258 |
lol sorry
n1 = primary number of turns
L1 = primary inducatnace
n2 = secondary turns
L2 = secondary inductance
when you divide n1 by l1 it should = n2 ,l2 |
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| RMCybernetics | Thursday, 29th November 2007 11:39am - No.2268 |
| No, these values would not be equal for a TC. The shape and size of the inductors are different so you would not excpect the same result unless L1 and L2 were wound on the same shape former with the same spacing and wire diameter. |
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| justin | Friday, 30th November 2007 1:58am - No.2273 |
so how do you tune a tesla coil then im confused. p.s i made the tuner
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| Dr Evil | Thursday, 24th January 2008 7:50am - No.2493 |
| shouldnt you be using a TTL timer IC and not a CMOS?? TTL's are more hardy and can tolerate more abuse than a CMOS devices. TTL's are cheaper too... |
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| Frank | Friday, 13th June 2008 11:01am - No.2825 |
| Will this tuner work with an AC Tesla Coil setup? |
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| RMCybernetics | Monday, 16th June 2008 1:18am - No.2837 |
| The part of the a TC you use this on is AC anyway so yes it will work for both setups. |
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| N4ISF | Friday, 19th September 2008 4:21am - No.3121 |
| The original version was called a "Dip Meter" It's the basic idea of using an oscilator with a milliameter to monitor current draw and interchangable coils to cover the spectrum needed. long ago they were made with a vacume tube, (I made one once) then transistors took over. In use the coil was brought into close proximity coupling with the coil to be tested and the oscilator tuned through it's range till the meter dipped, and that would be the resonant frequency of the tuned circuit. They were used most for the 0.5 to 30 MHz range. This one with a 555 for oscilator and LED instead of meter is a low frequency version. I will stick one together in the next couple days because I'm coming to where I need to do some low frequency coil tuning. |
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| der strom | Monday, 13th October 2008 5:43pm - No.3187 |
If I have a frequency meter, how would I "connect" it while testing the frequency? I assume I should connect it between one of the output leads and the part of the tesla coil that that lead would usually be connected to. Is this right?
And one more problem: when I don't connect the test leads to anything, the LEDs (I'm using two, facing opposite directions) go out. I assume this is right. But when I connect it to the secondary coil to test its frequency, the LEDs stay out throughout the entire testing range. Is this right?
thanks for your help, as always!
Der Strom. |
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| RMCybernetics | Wednesday, 15th October 2008 7:51am - No.3192 |
The frequency meter would connect between the test lads of the TCT.
Yes, the LED's will light up proportionally to the current flowing between the test leads. If it is not lighting at all, it indicates that to little current is flowing. You could try increasing the frequency by using a smaller capacitor for C3. |
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| Der Strom | Wednesday, 15th October 2008 4:36pm - No.3196 |
So do you mean I hook it up directly between the TCT probes (positive to negative) so it is basically in parallel with the part being tested? Or is it in series?
Sorry, I'm a little confused.
Thanks again!
-Der Strom |
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| RMCybernetics | Thursday, 16th October 2008 5:07am - No.3197 |
| Yes Parallel |
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| der strom | Monday, 20th October 2008 4:34pm - No.3205 |
One more question: what is a good range of frequencies for the secondary coil for a 4 in. diameter coil? Mine said something like 80 Hz. Does this sound normal? I always assumed it would be much higher, like in the kilohertz range.
thanks again!
Sincerely,
Der Strom |
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| RMCybernetics | Monday, 20th October 2008 6:19pm - No.3206 |
| It should be in the hundreds of kHz I would excpect. |
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| Yeri63 | Monday, 16th March 2009 11:28pm - No.3681 |
 I recently built your TC tuner to tune a new 1 inch dia. Tesla Coil. Connecting to the primary I do not observe any dim spots from the LEDs, just dim during the first 1/4 turn of the potentiometer, and then full on for the rest. I do however observe the multiple bright spots when connected to the secondary, so I believe the circuit is functioning correctly. Should I change C3 to another value so that I can find the resonance of the primary LC circuit; or, is the point just before LEDs stay full on the resonance point? I've tried changing the contact point on the primary (the last two turns are exposed) but see no difference using this tuner. |
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| RMCybernetics | Tuesday, 17th March 2009 1:27am - No.3682 |
That looks nicely put together. Be sure to post a pic when u get it working.
From what you describe, I would think it is not resonating in the range of frequencies on your TCT. Try just the second or 3rd turn (closest to secondary) as this would have a significantly higher frequency than the outer turns.
Also make sure your spark gap is shorted, the secondary is removed, and you may need to disconnect your transformer. |
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| Alexander L. | Friday, 27th March 2009 3:47am - No.3720 |
 Hello,
I am working with a water fuel cell that works most effeciently when pulsed at resonant freq (ReF). High voltage and low amperage are the most effecient ingrediants, though it should work with what i am using ie, a PWM @ 12V and up to 20amps.The ReF changes as the water level changes. Would this tuner be useful in identifying the ReF if so How? It is a design by Stan Meyer. I have attached a circuit diagram in case you are unfamiliar with the device. |
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| Fabio R | Saturday, 4th April 2009 4:25am - No.3735 |
I'm working on the same diagram posted by Alexander and I have the same question too.
It should work with pulsed frequency on the primary and secondary frequency by the way transformer is connected have a double pulse thus is twice primary f. the secondary is connected in parallel or series with the water capacitor which have a low resistance. Would it resonate even with the losses of the capacitor? Does the losses on the capacitor affect the Q factor?
And I would like to know if your lc resonator would be useful for this application too.
I would have a question about impedance transformation too. Which impedance is considered in the transformation? 1 the internal resistance of the driver circuit? or 1 + 2 the reactance of primary or 1+2+3 it depends on the load???? My circuit is a car battery and a mosfet irfz44n wich have 17.5 mOhm Rds(on). What is my internal resistance?
Thank you very much |
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| RMCybernetics | Saturday, 4th April 2009 11:29am - No.3739 |
Alexander L.,
You could possibly make the measurement accros your capacative load as it would have some resonant frequency when combined with the indoctors in the circuit. Remeber though, this circuit wont give you a frequency, you would still need an osciliscope to measure that.
Fabio R,
The losses in the capacitor greatly effects the Q factor. The resistance could mean that when you use the tuner, you just see the LEDs lit all the time. |
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A
DIY Tesla Coil Tuner
I used two other alligator clips to make a 6 inch jumper to short the
spark gap for primary testing. 
Calibration:
Secondary
Fo: To test the secondary's fundamental frequency, simply connect
the TCT between the ground and the base wire from the secondary as shown
below. Slowly turn the frequency through the range until the brightest
spot is found. The lowest and brightest frequency spot is the fundamental.
You may see the dimmer 3rd harmonic at ~3 x Fo. It is probably best to
test the secondary frequency on the coil in the actual configuration since
the secondary frequency is sensitive to the surrounding objects. 
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