Hytera PD362, Service Manual

Page: 94 / 141

Uc (430
‐
470 MHz)
Circuit Description
19
5.2.2
Receiver Circuit
The receiver circuit mainly comprises the RF band-pass filter, low-noise amplifier, mixer, IF filter, IF
amplifier and IF processor.
Low-pass Filter
Band-pass Filter1
Low-Noise Amp
AT-41511
Band-pass Filter2
Mixer
HSMS-2827
IF Filter
IF Processor
IF Amp
2SC5108
ANT
LPF
S21 ≤ 1.5dB
Ripple Inband ≤ 1dB
Stop band attenuation: -30dBc
S21 ≥ -0.8dB
S11 ≤ -15dB
S22 ≤ -15dB
Ripple Inband ≤ 0.4dB
BW(-3dB): 520MHZ
Stop band attenuation: -50dBc
TV
Tuning voltage ： 0.5-2.8V
Linear Gain≥ 12dB
S11 ≤ -15dB
S22 ≤ -15dB
S12 ≤ -30dB
Rejection at -1/2IF ≥ 15dB
Rejection at -2IF ≥ 80dB
Rejection at 2Fin-3IF ≥ 55dB
IIP3 ≥ 1dBm
Distortion ≤ 2%
Insertion Loss ≤ 2dB
S11 ≤ -15dB
S22 ≤ -15dB
Rejection at -2 IF ≥ 40dB
Rejection at -1/2IF > 8dB
Vdd ： 3Vdc
Gain ≥ 18dB
Current Drain≤ 8mA
S11 ≤ -15dB
S22 ≤ -15dB
S12 ≤ -25dB
NF ≤ 1.5dB
Insertion Loss ≤ 3dB
S11 ≤ -15dB
S22 ≤ -15dB
Rejection at -2IF ≥ 40dB
Rejection at -1/2IF >12dB
Lo
Lo Amp
2SC3356
Conversion loss ≥ -7dB
IIP3 ≥ 15dBm
Isolation ：
of Lo-RF> 30dB
of RF-IF> 25dB
of Lo-IF> 30dB
Lo input level
≥ 7dBm
NF ≤ 7
dB
Vdd ： 3Vdc
Gain ≥ 20dB
Current Drain ≤ 3mA
S11 ≤ -15dB
S22 ≤ -15dB
S12 ≤ -25dB
output level ≤ -11dBm
Centre Frequency ： 38.85MHz
Insertion loss ≤ 5dB
3dB Bandwith ≥ ±5KHz
Ripple Inband ≤ 1dB
Attenuation ：
@±12.5kHz ≥ 18dBc
@±25kHz ≥ 40dBc
@±2*2nd IF ≥ 85dBc
S11 ≤ -15dB
S22 ≤ -15dB
IIP3 ≥ 18dBm
Gain ≥ 4dB
Distortion ≤ 3%
Ripple Inband ≤ 1dB
3dB Bandwith ≥ ±6KHz
Attenuation ：
@±12.5kHz ≥ 18dBc
@±25kHz ≥ 40dBc
@±2*2nd IF ≥ 85dBc
Vdd ： 3Vdc
Input level ≥ -99dBm
2nd Lo:
Vdd
： 3Vdc
Frequency ： 38.4MHz
Current Drain ≤ 2mA
output level ≤ -22dBm
Pi Attenuator
Lo input level ≥ 7dBm
IL:0.5dB
Zin/Zout:50R
Attenuator Protect
RB706F
3Vdc
Double Circuit
2SC5108
3VFGU
VCTCXO
19.2MHz
BA4116FV
AF OUT
Receiver Front-end
The HF signal from the low-pass filter passes through the electrically tunable first-stage band-pass filter
controlled via APC/TV1 level, to remove out-of-band interference signal and to send wanted band-pass
signal to the low-noise amplifier (Q6005). The amplified signal goes to a second-stage band-pass filter
which is also controlled via APC/TV1 level, to remove out-of-band interference signal generated during
amplification, and to send
GHVLUHG HF signal to the mixer.
Th LV+) signal passes through the RF band-pass filter and low-noise amplifier and goes to the mixer
(D6009). Meanwhile, the first local oscillator (LO) signal generated by VCO passes through the low-pass
filter and also goes to the mixer (D6009). In the mixer, the
+) signal and the first LO signal are
mixed to generate the first IF signal (38.85MHz). Then the ,) signal passes through the frequency selection
network composed of LC, to suppress carriers other than the first IF signal, and to increase the isolation
between the mixer and the IF filter. After that, the first IF signal is processed by the crystal filter (Z6001),
and is sent to the IF amplifier circuit (Q6006) for amplification. Then the amplified signal goes to the IF
processor BA4116FV for processing.