Eric Dollard

[dR-Green]

* C is the coupling test capacitance between oscillator and coil.
** Fo is the center frequency measured with a storage oscilloscope.

Excellent stuff, thanks for the data

I rewound the extra coil last night based on a luminal frequency of F/1.24 so that's going to be tested next. Also bought some 2440x1220mm sheets of MDF earlier that will be used to make big diameter rings. The 12mm thick sheet is good but the 6mm is about as straight as a politician

[GSM]

* C is the coupling test capacitance between oscillator and coil.
** Fo is the center frequency measured with a storage oscilloscope.

Any chance of a photograph of this test setup please G_A ?
Especially showing drive source.

Cheers .......... Graham.

[Geometric_Algebra]

E.C. Test Setup



Vg: Tektronix FG 502 (50 ohm impedance) in rack, bnc to aligator clip leads.
C: Coupling capacitor, mechanically switched (dip) parallel arrangement of capacitors, several 2pf and 10pf, 1% tolerance, 0805 SMD, ceramic from Digikey, homebrew pcb.
Chx: Tektronix TDS 210, digital storage scope, channel
M: Radioshack Analog meter, switched to 50uA scale, 1n34a diode shunt across terminals, pomona mini-grabber test leads.
E.C.: 8", 46 turn, Extra Coil
Al. foil sheet as ground plane, finest quality.

[Geometric_Algebra]

Primary Inductance Test



The test setup is for the scope E.M.F inductance method using a series resistance of roughly 1 ohm (1/2 watt, I think, from the junk box).

This is a two loop, 20" diameter primary (1/4" separation between turns). Copper mass measurements/calculations show that I only needed a single turn. I made a mistake some where in my original design. Easy to change, but I will go ahead and test with this setup further.

[Geometric_Algebra]

8.0" E.C. Frequency Response



I estimate a 70.7% bandwidth of 65 k-cyc/sec from the chart.

[Geometric_Algebra]

Tandem Test

[dR-Green]

Is the tandem test without the condenser rings?

[Geometric_Algebra]

Is the tandem test without the condenser rings?

Yes, without.

One split ring is present, embedded at the top of the secondary form (the red mini-grabber, mechanically coupling secondary to extra coil, is attached at that point), but the top ring is not present.

If I am confusing terminology then do call me out, as I'm a bit behind on the experiments.

[dR-Green]

Yes, without.

One split ring is present, embedded at the top of the secondary form (the red mini-grabber, mechanically coupling secondary to extra coil, is attached at that point), but the top ring is not present.

If I am confusing terminology then do call me out, as I'm a bit behind on the experiments.

No I understand what you mean, thanks for the data. The only thing I'm not clear about is the frequency it was built for? Also do you have the direct connection frequency of the EC?

Based on your 70.7% 65 kc bandwidth with 33.1pF the magnification factor = 54.1

My old extra coil "free" magnification factor with direct connection (original calculated wire length with no terminal) = 57

I've just done the first test on a new extra coil wire length based on 1.24 times wavelength, the 70.7% bandwidth is 71.6 kc with direct connection.

Magnification factor = 49.12

So all extra coils are approximately within the same region without any terminal capacitance. After I do the frequency vs input capacitance on this coil then I'm going to start looking to see if the magnification factor increases (or reduces) with terminal capacitance. I couldn't do this with the last wire length because the "free" frequency was beyond my signal generator range.

[Geometric_Algebra]

The secondary was designed around a frequency of 1000 k-cyc/sec.

Could you clarify your calculation of the magnification factor?

No I understand what you mean, thanks for the data. The only thing I'm not clear about is the frequency it was built for? Also do you have the direct connection frequency of the EC?

Based on your 70.7% 65 kc bandwidth with 33.1pF the magnification factor = 54.1

My old extra coil "free" magnification factor with direct connection (original calculated wire length with no terminal) = 57

I've just done the first test on a new extra coil wire length based on 1.24 times wavelength, the 70.7% bandwidth is 71.6 kc with direct connection.

Magnification factor = 49.12

So all extra coils are approximately within the same region without any terminal capacitance. After I do the frequency vs input capacitance on this coil then I'm going to start looking to see if the magnification factor increases (or reduces) with terminal capacitance. I couldn't do this with the last wire length because the "free" frequency was beyond my signal generator range.

[dR-Green]

The secondary was designed around a frequency of 1000 k-cyc/sec.

Could you clarify your calculation of the magnification factor?

It is best if the magnification factor is given by coil maker, here is how it is done. Find peak reading on meter, its frequency noted as "carrier". Go down in frequency until meter reads 71% of the peak reading, this frequency noted as "Lower Side Band" (LSB). Go above carrier (CXR) frequency until again the meter reads 71% of the peak reading, this frequency noted as "Upper Side Band" (USB). Now subtract the LSB from USB. Take this difference, or 3dB bandwidth, and divide it by the CXR frequency. Finally take this result and divide it into one. Hence derived is the magnification factor. It is most important that this be as large as possible and every effort must be made to maximize it. The magnification transformer.

http://www.energeticforum.com/renewa...tml#post198884

In an earlier post Eric mentioned 70.7% which is what I've been using.

[Geometric_Algebra]

http://www.energeticforum.com/renewa...tml#post198884

In an earlier post Eric mentioned 70.7% which is what I've been using.

That helps a lot. Thanks.
So, Magnification = [(USB-LSB)/CXR]^-1 = CXR/(USB-LSB).

I get a direction connection magnification factor of roughly 17 for my E.C, centered around a frequency of 2994 kc. Not so good.

[dR-Green]

That helps a lot. Thanks.
So, Magnification = [(USB-LSB)/CXR]^-1 = CXR/(USB-LSB).

I get a direction connection magnification factor of roughly 17 for my E.C, centered around a frequency of 2994 kc. Not so good.

I was just editing my previous post, the magnification factor I gave you is wrong, I left my carrier frequency in the calculation instead of yours

[edit] Based on a carrier of 3226 kc, the magnification factor is 49.63 with 33.1pF.

Yes 17 seems low, I wonder if this is because the wire is spaced out more by you using less wire? I'm assuming the EC frame is from the original calculations?

In order to get my numbers to match Eric's (I repeat the calculations to make sure I end up with the same numbers),

(USB-LSB)/CXR = n
1/n = magnification factor

[Geometric_Algebra]

I was just editing my previous post, the magnification factor I gave you is wrong, I left my carrier frequency in the calculation instead of yours

[edit] Based on a carrier of 3226 kc, the magnification factor is 49.63 with 33.1pF.

Yes 17 seems low, I wonder if this is because the wire is spaced out more by you using less wire? I'm assuming the EC frame is from the original calculations?

Exactly. Less wire was used in this coil because I was confused about one of the constants used (PI^2/4 vs. (PI/4)^2 or 2.47 vs 0.62, roughly, If I recall correctly) which Eric hadn't clarified until later.

[dR-Green]

Exactly. Less wire was used in this coil because I was confused about one of the constants used (PI^2/4 vs. (PI/4)^2 or 2.47 vs 0.62, roughly, If I recall correctly) which Eric hadn't clarified until later.

I think this could save a lot of head scratching anyway. The EC calculated wire length was found to be too long, so then it was updated to λ/4/1.24. In order to be tuned to the system frequency of 3670 kc it needed a lot of capacitance, so the magnification factor of the extra coil was very low. So this is why I'm now using λ/4*1.24 wire length to test. The main objective is to see what happens with the magnification factor with different terminal capacitance, and at the same time see how the frequency of this wire length relates to the secondary. The next tested wire length would have been λ/4. On the same frame we can now expect the magnification factor to be reduced as the wire is spaced out more. So this saves us the mystery of figuring that out in the moment. Now the focus can be on the "tuned" magnification factor relative to the "free" magnification factor. Once an optimum wire length/tuning factor and corresponding magnification factor has been found then it looks like a new frame will need to be made for that wire length, I'm guessing with 62% wire spacing being the optimum?