| 摘要 |
535,633. Television ; wireless receiving apparatus. HAZELTINE CORPORATION. Dec. 18, 1939, No. 32444. Convention date, Jan. 17. [Classes 40 (iii) and 40 (v)] A television carrier-frequency signal-translating system for improving picture-contrast effects includes means having a non-linear signal-repeating ratio characteristic symmetrical with respect to the alternating current axis of said carrier-frequency signal. As shown, these means are constituted by a push-pull amplifier 14 between an oscillator modulator 13 and an intermediate frequency amplifier 15 in a television receiving system. The effective shape of the characteristic of this amplifier can be varied according to the contrast effect desired by varying the grid bias of the tubes 21, 22. A volume control potentiometer 16a following the detector 16 is adjusted simultaneously with the adjustment of the grid bias of the amplifier 14. |
