Schneider CTV 2790.9

[Bobo]

I need to add 6,5 and 6,74 MHz IF for sound.....Problem is that this TV is from German production and it have only 5,5 and 5,74 MHz IF...In my country does not work it...I can to buy kvaziparallel konverter, but the tuner has symetrical IF output...I dont know how can do this..I have tried everything what I can.
Thaks for all....
Marek, Czech Repuplic