unun

[Crowling]

You need to probe both ends of the winding and you'll see on the scope screen when the phase starts to shift from one end of the winding to the other as the frequency is increased. If it is a -43 core you should start to see a noticeable phase shift around 7,000 kHz.

Edit: to look at this on the scope you don't need a primary and secondary. I would wind like 14 or 15 turns on it with a single winding, probe both ends of the winding and look at the sine waves. If they are super-imposed on one another there is no phase shift. But as frequency goes up one sine wave will start to shift from the other one. You don't need to measure the phase angle, just a visual representation of where the input and output start to get out of phase. Different ferrite mix cores have different response to frequency and I know from experience that a quality -43 will start to exhibit phase shift around 7,000 kHz, which is a way to identify the mix that was used in the core. You can test both your "known" and "unknown" cores to see what the difference is and if the "unknown" core doesn't match the "known" ones, it's not suitable to be stacked with the "known" cores.

You can also put a winding on the core and measure the inductance of the winding with a LCR meter or analyzer and see how the "unknown" stacks up with the "known" ones. Measuring the inductance of a winding on it will give you an idea of the initial permeability of the core when it's cold. A -43 core has quite a bit higher inductance than a -52

You need to probe both ends of the winding and you'll see on the scope screen when the phase starts to shift from one end of the winding to the other as the frequency is increased. If it is a -43 core you should start to see a noticeable phase shift around 7,000 kHz.

Edit: to look at this on the scope you don't need a primary and secondary. I would wind like 14 or 15 turns on it with a single winding, probe both ends of the winding and look at the sine waves. If they are super-imposed on one another there is no phase shift. But as frequency goes up one sine wave will start to shift from the other one. You don't need to measure the phase angle, just a visual representation of where the input and output start to get out of phase. Different ferrite mix cores have different response to frequency and I know from experience that a quality -43 will start to exhibit phase shift around 7,000 kHz, which is a way to identify the mix that was used in the core. You can test both your "known" and "unknown" cores to see what the difference is and if the "unknown" core doesn't match the "known" ones, it's not suitable to be stacked with the "known" cores.

You can also put a winding on the core and measure the inductance of the winding with a LCR meter or analyzer and see how the "unknown" stacks up with the "known" ones. Measuring the inductance of a winding on it will give you an idea of the initial permeability of the core when it's cold. A -43 core has quite a bit higher inductance than a -52 or -61.

Before I drag my old scope out of storage is there a way to send photos?

 

[AC9KH]

Before I drag my old scope out of storage is there a way to send photos?

In the upper toolbar of your posting box there is an 'insert image' icon there. Just drag a picture onto the popup that appears, but make sure it's suitably downsized for web first, using some sort of photo editor.

 

[Crowling]

 

[Crowling]

That’s 2 primary and 14 secondary without cap on mystery core

 

[Crowling]

 

[Crowling]

That’s with 100pf cap on mystery core lol.

 

[Crowling]

Ps. Got my NanoVNA-H4 today. It’s really nice!

 

[prcguy]

View attachment 182255

An FT-240-43 core is less than $10. I think you used up way more of that in labor trying to see if the mystery core will work, which it doesn't appear to.

 

[Crowling]

An FT-240-43 core is less than $10. I think you used up way more of that in labor trying to see if the mystery core will work, which it doesn't appear to.

I have 4 new 240-43 cores from Mouser. That core was an experiment. I’m disabled and retired so my labor isn’t important.

 

[prcguy]

I have 4 new 240-43 cores from Mouser. That core was an experiment. I’m disabled and retired so my labor isn’t important.

You are productive, worthwhile and needed. Your labor is more important than you can ever imagine....

 

[Crowling]

In the upper toolbar of your posting box there is an 'insert image' icon there. Just drag a picture onto the popup that appears, but make sure it's suitably downsized for web first, using some sort of photo editor.

I was going to return my 4 cores (240/43) to Mouser but was told NOT to send them back to just keep them and they refunded my card!! Would you be interested if I pay you and shipped them to you, in winding a transformer for me? I will pay for the wire as well as your labor. I have a “box” for it and hardware. I just need someone who knows what they’re doing to wind the transformer. I’ve had NO SUCCESS lol.