| 摘要 |
PURPOSE:To prevent noises at the switching of transmission and reception, by turning off an antenna at the switching, transferring the frequency of a PLL circuit and then locking the PLL circuit. CONSTITUTION:At a receiving state, a transistor (TR) Q1 is on and a receiving antenna switching diode D1 is also on. When a TX button is turned on, the TR Q1 is turned off by a signal from an antenna controlling part and the frequency of the PLL circuit is transferred. After completing the transfer and locking the PLL circuit, a TX power supply and a transmitting antenna are turned on. Consequently, noises can be prevented at the time of switching. |
