[Alex KL-1]

By the way, I observed the interlace in my TV's and made some ranking of interlace smoothness-:
Using my most picky device for interlacing (my PC):

#My homemade TV with TDA9373 processor (Philco programmed, 2005): the best so far. Zero interlace troubles. But I made it with shields in critical areas, and is a IC with logic and PLL's.

#Sony TV-700U (1966): Impressive. So simple circuit, but very easy to achieve the interlace point, and very stable. Not needed to change the control anymore. But again, Sony put the flyback inside a shield, maybe for not frying the signal Ge transistors. This confirms the H pulse interfering with V sync, in lesser set's without shielding or good layout.

#Toshiba TS-207 (1987): with TDA2578. Good, but become sensitive ater 30 minutes or more, and not interlaces more. ******

#10" Philco portable (1976): Good after changes. Perhaps better than the Toshiba.

#Telefunken TV-231 (1964): originally horrible; good after vertical mods.

#Telefunken TV-472V (1978): discrete vertical stages. Picky for interlace, but relatively stable when one achieve the point. I don't played with it yet.

******NOTE: in fact, probably my PC become lazy with interlace after some time, but the good TV's yet interlace properly.
The worst TV's didn't interlace with any modern device, not only my PC (like original tube Telefunken or original Philco portable).