i think i order 2c42 so for high voltage i must use ht25? seems coil outputs in KV , and in ranges up to 400-600v it will be enough to use 10x probe?
Do not attempt to monitor the secondary of ignition coils via a directly connected anything. Monitor the primary side which mimics the waveforms of the secondary.
Here is a typical spark event captured on the primary side the ignition coil;
The 250 VDC spike is what is required of the coil's output to ionize the plug gap--on the secondary side this would be 12 to 15 kVDC. THe flatter and lower voltage portion is the actual plug firing event, 600 V to 1.5 kVDC on the secondary side.
This capture is the primary side of a COP on a 2003 Mustang GT V8;
Note that the engine control system fires the plug three times in rapid succession. It does this to ensure a full and complete burn at idle, and up to 1100 RPM or so.
THe Hantek HT25 is an inductive pickup probe, it's output to the scope is < 1.0 V -- BTW, you can make one of those with a copper pipe cap and a piece of PVC pipe.
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Here's A YouTube video of a fellow making that pictured above. There's not one bit of magic involved.
And here, FWIW is a capture of a primary side firing event of a 2003 Suzuki Burgman 400 maxi-scooter's ignition coil; it is a near classic waveform of a spark plug's firing.:
It was captured on a test bench, the coil being activated by an ignition coil test apparatus of ny own design (shown here with an aftermarket "high-performance" Ford COP and an air-gap HV tester):
A good coil will fire strongly across a 15 to 16 mm air-gap; if the best one can do is 10 to 12 mm,lI start to suspect a bad coil.
Here's an .mp4 video of a test.