Vectrex & LZX video synth - Curliing effects

I was trying to achieve vector rescanning on the vectrex but instead got some rather
interesting  though unexpected "curling" effects.

Has anyone does something similar ?

some pics of the LZX setup.

tHE image on the vectrex was really small initially, but with amplification i was able to fill about 2/3 of the screen

..

I connected a horizontal ramp to the X input, a vertical ramp to Y and the composite output to the Z. 

Maybe I should use a luma output ?

 

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