Cubik

Hi! I am having problems with displaying Lissajou patterns (for educational purpose) with a Tektronix 2246 and I need some help. I have one and only one function generator set to display sinusoidal signal. I put a T BNC connector on the output plug of the generator on plug to 50 ohms BNC to it and I have connected the 2 ends to the scope on CH1 and Ch2. I have inverted the CH3 to have the exact same signal and frequency inverted. I have changed the mode to XY and I am getting 2 diagonals lines (like this <). From there I cannot get any Lissajou figures. I have tried to change to different mode, different type of current and different everything but nothing works. I would really appreciate a little help from confirmed technician which I am obviously not... Thank you.