| 摘要 |
The mixer circuit generates a signal of a standard IF, using a tunable mixing oscillator. In front of the mixing circuit is coupled a standard HF input circuit with amplifier stage(s) and filter(s). A converter circuit (16) with a second mixing stage (20) and a tuned mixing oscillator (21) is connected instead of the standard HF input circuit (8). The replacement takes place in an operational mode for reception of an alternative standard TV transmission in which the position of the audio carrier (T3) is exchanged with that of the video carrier (B3) w.r.t. their standard frequency positions (B1, T1) within the transmission channel. The converter circuit pref. has the same HF amplification as the standard HF input circuit.
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