Ok, i did screw up the math of the time/wavelength calculations as stated in post #30 and to be seen in the video there.

I did ask to check it

Here a retry.

As can be seen in the screenshot below, the forth and back reflection pulse is 1.07us depending on where the 2th marker is positioned.

I think it should be in the middle like shown (1.07us), but others mentioned that it should be on the start of the pulse which then would measure 996ns.

For the time being i keep my 1.07us which i have measured severall times now. (why does my 3ns wide pulse get smeared out to this ugly 200ns or so reflection pluse? Capacitance?)

So the 1.07us is the forth and back reflection on my 90.24m (measured) long transmisstion line.

The single length time reflection time then would be 1.07us / 2 = 0.535us.

As the speed of light is 299792458m/s = 299.792458m/us the pulse traveled 299.792458m * 0.535 = 160.38m.

So the electrical length of my transmission line coil is 160.38m

As my transmission line is only 90.24m long, the calculated velocity factor of it is 90.24/160.38 = 0.56.

So we have:

a physical transmission line length of 90.24m

an electrical transmission line length of 160.38m

a velocity factor of 0.56

char. impedance of 30 Ohm

capacitance measured 20nF

Inductance of each coil 828uH

According to

http://www.wavelengthcalculator.com/ a wavelength of 160.38m corresponds with a frequency of 1.870MHz (1 cycle), so half a wavelength resonance would be at 935KHz.

This 935KHz is what i found as my 1st reonance points, but this is creeping up in frequency while trimming my capacitors (823KHz with 11pf, 935KHz with 6pf, and presently 1180KHz or so with about 1pf)

My idea was that this transmissionline frequency (open ended coil) should stay fixed no matter what capacitor value i connect.

What should (and does) change when trimming the cap is the LC resonance of the series LC circuit (not open ended coil)

I made a 1Mohm/10Mohm voltage divider to probe the both A and B outputs as suggested by Smudge, see diagram.

Works fine, but no phase shifts noticed yet.

Regards Itsu