1-24 (No.RA033<Rev.001>)
2.6.5.9
Temperature sensor
The temperature sensor (IC9) monitors temperature around CONTROL-UNIT.
The temperature is recorded for the NOR-FLASH memory (IC790).
2.6.5.10 Squelch circuit
The squelch circuit amplifies the demodulated noise signal from IC150 after filtering through the BPF circuit.
The processed digital noise signal is applied to CODEC IC452, and is converted from digital to analog.
The amplified signal is then converted to a DC signal by the detection circuit.
The converted signal is fee back to IC200
2.6.5.11 18.432MHz clock PLL circuit
The PLL circuit is installed in the control unit (XC1-064) for operating the IC150, IC200 and IC452.
The PLL circuit consists of X50 (18.432MHz), IC52, IC50, Q51 and Q55.
The purpose of this PLL circuit is to synchronize with the 19.2MHz reference signal controlled by the 10MHz OCXO or X601(20MHz
divided),input external reference (10MHz) in transmitter unit.
Q55 is a 19.2MHz buffer amp signal input from the transmitter unit.
The signal from the transmitter unit is supplied to IC52 pin8 (reference signal input).
18.432MHz from X50 is buffered by IC50 and distributed to two routes.
One is amplified by Q51 and input to IC52 pin6 (RF signal input).
The other is supplied as a clock for IC150, IC200 and IC452.
IC52 compares the reference signal and RF signal and detects their phase errors.
This phase error signal is output from pin2 charge pump, passed through the LPF and is supplied to X50 voltage control pin.
Fig.19 PLL circuit
2.6.5.12 Audio circuit
•
Audio amplifier circuit
The audio amplifier circuit is located in the control section of the Control unit (XC1-064).
The 3W output audio power is available from the pin15 TEST/SPKR connector “SPO”, “SPG” on the rear panel to the external speak-
er in the case of a power supply voltage of 13.6V and a 4
Ω
load.
•
Microphone circuit
The signal from the microphone is passed through the AGC circuit located in the Display unit.
So that it may not saturate.
This circuit consists of IC908, Q909, Q910, D923 and D924.
The AGC control the amplifier gains using the detected audio signal depending on the positive and negative peaks of the signal
amplitude.
The audio signal goes to the control section of the Control unit from the Display unit.
CLK BUFFER
IC50
LOOP
FILTER
PLL IC
IC52
VCTCXO
X50
(18.432MHz)
19.2MHz( fromTX_UNIT)
to IC150,IC200,IC452
18.432MHz out
AMP
Q55
AMP
Q51
CN102
Summary of Contents for NXR-5700
Page 121: ...MEMO ...
