| 摘要 |
PURPOSE:To compensate temperature characteristics of a transmission level by a thermistor by providing a bias circuit, including the thermistor, to a temperature compensating attenuator with a non-linear element in the intermediate frequency band of the transmitter of a heterodyne repeater. CONSTITUTION:An intermediate frequency signal inputted from terminal 1 is set by temperature compensating attenuator 2 to a level which corresponds to temperature variation and then converted into a microwave by mixer 3. Further, the signal is amplified by amplifier 5 and transmitted from output terminal 6. As a temperature rises, the resistance value of thermistor 13 falls. Consequently, a voltage applied across pin diode 12 as a non-linear element decreases and the resistance value of pin diode 12 itself increases. Therefore, a rise in temperature causes the whole attenuation amount of attenuator 2 to decrease and characteristics of a temperature to the transmission output level of the entire device becomes reverse as compared with those without temperature compensation and kept constant against variation in temperature. |
