- ページ 18
ラジオ Motorola Professional GP640のPDF サービス情報をオンラインで閲覧またはダウンロードできます。Motorola Professional GP640 30 ページ。 Professional radio, power distribution and controller
Motorola Professional GP640 にも： ユーザーマニュアル (32 ページ), 仕様書 (2 ページ), サービス情報 (28 ページ), サービス情報 (32 ページ), サービス情報 (26 ページ), サービス情報 (43 ページ), サービス情報 (30 ページ)
ページを印刷する
2-8
4.2
Voltage Controlled Oscillator (VCO)
(Refer to Figure 2-4 and the VHF Voltage Controlled Oscillator schematic diagram)
The VCOB IC (U3801), shown in Figure 2-5, in conjunction with the Fractional-N synthesizer
(U3701) generates RF in both the receive and the transmit modes of operation. The TRB line
(U3801 pin 19) determines which oscillator and buffer are enabled. A sample of the RF signal from
the enabled oscillator is routed from U3801 pin 12, through a low pass filter, to the prescaler input
(U3701 pin 32). After frequency comparison in the synthesizer, a resultant CONTROL VOLTAGE is
received at the VCO. This voltage is a DC voltage typically between 3.5V and 9.5V when the PLL is
locked on frequency.
Rx-SW
Tx-SW
(U3701 Pin28)
Steer Line
Voltage
(VCTRL)
RX VCO
RX Tank
Circuit
TX VCO
TX Tank
Circuit
Pin 20
Pin7
Pin13
Switching Network
Vcc-Superfilter
Pin3
Collector/RF in
Pin4
RX
Pin5
Active Bias
Pin6
TX
Active Bias
Pin16
Pin15
Vsens
Circuit
Pin18
Vcc-Logic
(U3701 Pin28)
Figure 2-5 VHF VCO Block Diagram
AUX3 (U3701 Pin2)
Prescaler Out
TRB_IN
Pin 19
TX/RX/BS
Presc
U3801
VCOBIC
Rx
Tx
Pin2
Pin1
Pins 9,11,17
Tx-I adjust
Rx-I adjust
THEORY OF OPERATION
U3701 Pin 32
Pin 12
LO RF INJECTION
Matching
Network
RX
Pin8
(3701 Pin28)
Pin14
VCC Buffers
TX
TX RF Injection
Pin10
Attenuator
Low Pass
Filter