How can I adapt Col-R-Tel circuits to todays television?
ANSWER. To restore the IF bandwidth sufficiently to drive a color adapter, you need gain. The gain comes from a stage or more of chroma amplification. You’ll have to add these gain stages. Circuits appear in old TV trade school textbooks. Most such books bear a copyright date between 1973 and 1979. Before 1973, color TVs still used tubes. After 1979, color TV circuits became more and more integrated. Newer texts responded by replacing the detailed circuit analysis with block diagrams and cursory discussions. (I wonder how anybody learns from these presentations? If you need to design an amplifier, a block diagram isn’t much help.) Anyway, if you add the chroma bandpass amplifiers, then you probably need a delay line. Now the circuit isn’t so simple anymore. Those bandpass amps require tuning, peaking coils and traps. The delay line must be the right one, or the colors appear in the wrong place. At least we don’t have to build our delay lines today. The old timers did, though. Want to k
