Look, coercive force is around 40 A/m and remanent magnetization or remanence could be as high as 1T for GOSS so forget about it.
After that you have measured the membrane capacitances so accurately, do you see any possibilities to measure the transformer and/or the delay line inductor with your Bode 100 in the near future ?
It would be great if this project could be finalized as close to the real thing as possible.
I'm still clearing out junk in the shop to make room (Stygian sables reference goes here). I'll target some measurements this week. It will be an interesting project.
Partway through the setup. Attached is the forward response of the transformer itself in circuit. I'm measuring from XFMR input terminals to XFMR output terminals with a pretty small signal (200 mV). I need to build some probes to handle the HV and also look at whether the BODE100 would show something this doesn't.
Here are plots with the delay line connected and disconnected.
Also the probe in this case is approx 100K. I'll try to make a useable probe that gives an X100 response. It won't be that simple with the high voltages, but I could then drive with some significant signal and measure distortion.
Great that you have already spent some time in measuring and producing some interesting images.
But to be honest, I still have a bit of a problem to understand these graphs.
What is the blue line and the same question for the yellow line.
Are these 2 resp. input signal versus output from your 100K HV probe, and is this all without the 1R65 and 1R5//220uF at the input ?
And what is the red line in the last image ?
You are still working on a 100K secondary probe.
This will mean the equivalent of 1R7 at the primary !
When measuring a xmfr with your Bode as in posting #54 you won't need a high voltage probe, but you are most likely aware of that.
Looking forward for additional data.
Sorry for not proving some details to help explain the plots.
On the last plot which goes from 1KHz to 100 KHz the red trace is the voltage ratio of the transformer measuring input to output with only the 100K (maybe 50K) of the differential probe of the Praxis across it.The Teal trace is the same with the delay line connected. The Yellow trace is the phase relationship between input and output with the delay line connected.
I'm not sure how you get 1.7 Ohms at the primary. The plot shows the 100X turns ratio and the impedance transform is the square root of the turns ratio or 10K I believe.
I'm using Praxis because its useable as a full 2 port differential network analyzer here. In these plots I'm using a headphone test amp to drive the system since its wahat is connected. I'll be building an HV probe interface for the Praxis today. That will allow me to drive the transformer at higher levels with a test amp and see what comes out. If the connections were easier to get to i would also look at the delay line outputs but they are buried.
The max in on the Bode is listed at 50V before damage and the source Z is 50 Ohms. I'm not ready to risk that yet. Maybe if I can interface a differential HV probe I have.
But I'm still not sure what and how you are measuring.
I suppose you are driving both transformers because you measured with and without delay lines, which can hardly be done with only one transformer.
So are you indeed driving both transformers but measuring on the output of just one, and is the drive signal for the teal line applied with the 1R65 resistors and the 1R5//220uF still in place, and was then measured between secondary and gnd ?
And for the red line was your differential probe connected on one side to the primary and with the other side to the secondary ?
The supposed ratio of the XFMR is 120, or 41.6dB, which is more or less the case with your red line.
When connecting a 100k probe to the secondary with a gain of 240 for both transformers, 100K / (240)^2 = 1R7, that's how I calculated this.
In case of just measuring the output of one transformer this will give 100K/(120)^2 = 6R9.
Why do you bother about the voltage the Bode can generate ?
Applying one or two Volt max and a few steps below will be more than enough to measure the transformer.
You only have to measure an isolated transformer open ended and short circuited, as in posting #54.
Here are measurements of 1 transformer. I disconnected one primary wire and the delay line for these measurements.
1) primary impedance secondary shorted
2) primary impedance secondary terminated with 100K Ohms
3) Transformer response "gain" and phase.
4) primary impedance secondary open
The primary impedance with the secondary terminated with 100K is around 8 Ohms, which sort of makes sense. I was wrong there. The turns ratio is much closer to 100. The measurement suggests a ratio of 106 to 1.
Do you need secondary impedance measurements the same way? I can also provide the discrete data files.
Getting to delay line coils is not happening here. They would require a lot more disassembly of the working parts of this speaker. Its owner is expecting it to work again.
I can measure the secondary distortion VS. frequency tomorrow after building the HV probe.
I need to reassemble the speaker soon. These are a PITA to balance upside down for any length of time.
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