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Measuring resonant coil outputs

 

Hi all,

I’m new to this group, a physicist by background but also new to using a spectrum analyser. Before I go and actually buy the Aursinc V0.3.1 model, I wanted to ask about how I might go about making measurements relevant to my research so I can be sure this is the best and most affordable approach.

To summarise, I am investigating resonance in coils driven at radio frequencies and high voltages and looking at the standing waves that result from certain coil configurations and wire lengths. To make it easier to show what I’m doing, I attach some graphics showing the circuit (without an output load), a typical coil configuration and an example of standing waves that show on a scope using a low-powered setup of 18V to the primary coil.

In particular, the queries I have are:

  • Can I detect what frequencies are emanating from the coils by using the supplied aerial placed within say 50cm of the coils?
  • What sort of attenuator would I need to cope with the high voltages and power in the secondary in particular?
  • Are there any others known about how are doing this type of measurements?
  • Will the tinySA-App work with Windows 10?

Thank you in advance for any help.

?

?
Julian Perry
Kerrowenergetics.org.uk
 

What frequencies are you targeting?
The supplied antenna is good for 50 MHz and higher but is a lot less sensitive for 10 MHz and lower
For low frequencies you better use a (home made) loop antenna
--
Designer of the tinySA
For more info go to

 

On 04/04/2025 09:54, Kerrowman via groups.io wrote:
Will the tinySA-App work with Windows 10?
Yes.

David
--
SatSignal Software - Quality software for you
Web:
Email: davidtaylor@...
BlueSky: @gm8arv.bsky.social, Twitter: @gm8arv
 

Yes, an important question. 10kHz - 20MHz I think is reasonable. I know the tinySA is not accurate below 100kHz but I have heard that by making some Config adjustments then it will detect them.
--
Julian Perry
Kerrowenergetics.org.uk
 

:)
--
Julian Perry
Kerrowenergetics.org.uk
 

What about the issue of potentially damaging the SA? How can I work out the dB of the fields surrounding the coils to best protect it? I do have one of those cheap field meters for elec and mag fields, which measures in V/m and ?T.
--
Julian Perry
Kerrowenergetics.org.uk
 

On Fri, Apr 4, 2025 at 03:57 AM, Kerrowman wrote:
I know the tinySA is not accurate below 100kHz but I have heard that by making some Config adjustments then it will detect them.
The tinySA Basic (0.3.1 model) will actually work well down to 10 kHz but you lose some dynamic range
--
Designer of the tinySA
For more info go to

 

When you are probing with a loop antenna you can start at large distance (two meters) and reduce the distance if there are no strong signals.
Unless you are exiting the coil with a LOT of power, then you may have to start at larger distance.
To be absolutely sure, you can put a 20 or 30 dB attenuator directly on the RF connector of the tinySA and connect the antenna to the attenuator.
Make sure you never ever touch anything with the telescopic antenna.
--
Designer of the tinySA
For more info go to

 

Thank you. Are the attenuators specific to your design of tinySA or are they are standard fitting device available from various outlets?
?
One other point; what feature of a single loop (of 2mm tinned copper wire) determines its optimum detection frequency and is there an optimum diameter or configuration for my frequency range (e.g. square vs circular)?
?
--
Julian
 

1)? For those who didn't bother to look at the diagram, it shows specifically 35 kHz.? Enough said.....

THE REST:

I as well come from a physics background.?

Be extremely careful with those power levels.? At 35 kHz and 1 kV feeding a spark gap, you are evidently using shock excitation to look for ring-down and harmonic generation from your resonant LC network.? As a precaution, I would strongly recommend installation of the following from MiniCircuits installed at the input of the TINYSA.? Leave it installed.?

? ?? VLM-33W-2W-S+?

It is presently under redesign by MiniCircuits, but doing what you do, I'd almost "require" you install it or equivalent to protect the TINYSA - or any SA, for that matter.

Considering your application, that should be installed in addition to attenuators? It would be best to have a selection to match the levels of harmonics and fundamentals excited by the shock exitation.? These are available from ebay, or, better quality, Pasternack.? Values might include the following:? 20 dB, 10 dB, 6 dB, and 3 dB.? Small SMA style packages at 1 watt or less are adequate for your application. ?

Again, considering your power and voltage levels, I'd start with the short included antenna.? As such, it is an extremely short portion of a wavelength.? Therefore, you likely won't experience any frequency bias from the antenna up to where it becomes a 0.1-wavelength and more. ?

Also start at some distance from your spark gap and the LC network.? Approach the operating system with caution to, again, be "kind" to the SA. ?

You will also require multiple discharges of the spark gap to capture the ring-down and harmonic structure.? It would be advised to use the MAX HOLD function to capture the sum of a number of gap discharges.? Otherwise, the sweep is too slow (andy SA will exhibit this) to faithfully capture what you're after.??

I've done just what you are looking for before retirement for Uncle at KAFB in Albuquerque.? All I'll write based on the experience with Uncle is: "It's amazing what can be done with wide-band RF pulses".? I've also experimented as you here in my small lab.? If you want to email me offline of the group, please - I'm open.? Emails are:

? ?? DaveArea51A at gmail dot com
? ?? W zero LEV at arrl dot net

Glad to help where I can.

Dave - W?LEV? ? ??


On Fri, Apr 4, 2025 at 9:53?AM Kerrowman via <979jules979=[email protected]> wrote:

Hi all,

I’m new to this group, a physicist by background but also new to using a spectrum analyser. Before I go and actually buy the Aursinc V0.3.1 model, I wanted to ask about how I might go about making measurements relevant to my research so I can be sure this is the best and most affordable approach.

To summarise, I am investigating resonance in coils driven at radio frequencies and high voltages and looking at the standing waves that result from certain coil configurations and wire lengths. To make it easier to show what I’m doing, I attach some graphics showing the circuit (without an output load), a typical coil configuration and an example of standing waves that show on a scope using a low-powered setup of 18V to the primary coil.

In particular, the queries I have are:

  • Can I detect what frequencies are emanating from the coils by using the supplied aerial placed within say 50cm of the coils?
  • What sort of attenuator would I need to cope with the high voltages and power in the secondary in particular?
  • Are there any others known about how are doing this type of measurements?
  • Will the tinySA-App work with Windows 10?

Thank you in advance for any help.

?

?
Julian Perry



--
Dave - W?LEV
 

Hi Dave,
?
Lots of useful info there. Thanks. I will also write separately to you.
--
Julian

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