Anybody with a Hantek HT25 Probe

[chinoy]

So I am trying to build this probe for my scope.
Why not just buy one ?.
Well the HT25 does not work with COP so I would actually have to buy 2. i.e. the HT25 and the HT25COP thats about 200$ USD which is more than what my scope cost me. (Price in my country). On aliexpress its only 14$ I think. But we have a trade war going on.

I would rather have one solution which works on any ignition.
I got this idea from scannerdans forum.
https://drive.google.com/file/d/1TdjjBygBFbAsvjbExIHkSZwymr2Vn6Cv/view?usp=sharing

This will work with any type of ignition. And I think it will work far better than the hantek unit. Because its made from copper. And I can tune the length and dia.

Where I am stuck is how do I calibrate it to real world values. i.e. I need to know what value cap and resistor is used in the HT25.
The only info I could find was this. Again from scanner dans forum.

For the HT25
At Scope BNC: + to Ground 33k ohms,
At Pickup: + to Ground 33K ohms
Scope end to Pickup End 0 Ohms on both + and Ground conductors.

So any over voltage protection and attenuation going on inside the black box on the lead isn't being done by resistors.

Another Idea I am thinking of trying is a pickup coil from a Timing strobe light. But that again will not work for Coil On Plug.

Any inputs or ideas much appreciated. I will start testing some initial ideas in a few days. Waiting on some copper sheets to land up.

What would really help would be to know whats inside the black box on the probe.
Here is another idea where he just uses a wire. With the HT25
Just fond this. As per this a simple wire also works. But he still uses the HT25.
https://youtu.be/e59atXyNNPA