| 摘要 |
PURPOSE:To reduce the cost of facilities and to facilitate adjusting operation, and to improve the precision of characteristic inspection by leading out a voltage generated by a PLL circuit, and adjusting the tuning circuit of the high-frequency tuning device prior to the characteristic inspection so that the value of the voltage corresponds to a specific modulation frequency. CONSTITUTION:A specific AV signal is inputted as a sample signal S to an RF modulator 1. The frequency conversion output C generates as a result is demodulated by a demodulator 4, but the PLL circuit 4a generates the control voltage V corresponding to the frequency shift of the modulation output C from the specific frequency set for a modulator 4. This voltage is displayed on a voltmeter 6 and the variable element, e.g. variable capacitor of the tuning circuit of the high- frequency tuning device 1 is adjusted over a look at how much the modulation output C deviates from the frequency on the display. This adjustment is easily made because a clear reference is displayed on the voltmeter, and the precision of it is high. |
