Furuno HS-8800 User Manual

5.4 Block Description
5-6
5.4 Block Description
5.4.1 CH70 RX (05P0775)
This board is a CH70 WR. This board converts frequency from CH70 (156.525 MHz) to
2
nd
1F and outputs it into CPU board. A self- test of this board does not check RX circuit
but inputs CH70 test signal from CH70 IF OUT line to see if that can be detected or not.
As for antenna, CH70 WR exclusive antenna is used and other way, when watching
CH70 through TR antenna a modification of internal wiring will be necessary. In this
case, CH70 receiving signal cannot receive during any transmissions. CH70 receiving
signal is received from J5 port on TX/RX board.
The main specifications are below.
Table 5.4.1 Specification of CH70 RX PCB
Item Specification
RX frequency CH70 (156.525 MHz)
Antenna input (J2) Impedance 150 MHz/50 ohm
1
st
IF frequency 38.3625 MHz
2
nd
IF frequency (CH70 IF OUT) 37.5 kHz/5 k ohm, －60 to +10 dBm output
1
st
Local frequency 23.6325 MHz x 5 =118.1625 MHz TP1 level: +4 to 7 dBm
2
nd
Local frequency 38.4 MHz (0 dBm, 50 ohm) TP4 level: 0 to 3 dBm
DSC sensitivity (CH70 board) Input level of SINAD is below 3 dBuV
DSC sensitivity (total)
Antenna input level below 0 dBuV ! BER (Bit Error Rate):
lower than 10
-2
(Acceptable level: 6 dBuV.)
Fig. 5.4.1 CH70 RX (05P0775) Block Diagram
FL2: SAW FIL
(156.525MHz)
BPF(L/C)
ISS271
BPF(L/C)
CR6, 7
CR4, 5
FL1
(38.3625MHz)
U2
(TA48L033F)
Q2Q3 Q4
Q1
Q8
U30
CPU
U20
DSP
U17
CODEC
CPU
05P0773
CH70 RX
05P0775
PMBFJ310
Y1:TCXO
(23.6325MHz)
2SK882
2SC3356
2SC3356 2SK882
Q7
2SC3324
MA728
37.5kHz
38.4MHz
+15V
+5V
TP1
TP4
TP2, 3
X5
(118.1625MHz)
(118.1625MHz)
R36
100
R37
100k
CH70 IF OUT
CH70 TEST
J3-#5
J3-#1
J3-#2
J3-#3
J2
J1
REG.
+3.3V
CH70 ANT

Furuno HS-8800 Specifications

General

Brand	Furuno
Model	HS-8800
Category	Cordless Telephone
Language	English