[radiomec]

NewVista, for converting a color PAL signal in NTSC, it needs to turn upside down the color signal of the even lines and to let unchanged the odd lines, with a flip flop as you said. For convert a NTSC tv set in a PAL one, it can be useful to use last IF stage of the color signal connected directly to the flip-flop. Of course the accord of the color IF transformers and the video IF must be changed and also the quartz must be substituted with a 4.43 MHz one. Furthermore the PAL tv sets have a color delay line that delays the color signal for the time of one line and then the delayed signal is added together the normal one. Another problem is the horizontal frequency at 15625 Hz instead of 15750 and the vertical frequency at 50 Hz instead of 60 Hz, also if normally all the tv sets can be adjusted with these frequencies. However this is not longer important to make it, because digital decoders make this conversion without problems. So to use US tv sets here in Italy is quite simply. We have to had only an RF modulator with the audio intercarrier frequency at 4.5 MHz.