101
CHAPTER 12. NBDP TERMINAL CIRCUIT
12-1
OVERVIEW
SN-100 consists of NBDP Receiver, CONNECTION BOARD, CPU BOARD, PLL BOARD, and
POWER SUPPLY.
There is power input, SRG-3150DN connector, W/K receiving connector, TX AND RX cable
connector, EARTH Plate, keyboard connector, EMC LIGHT connector in the down part of
rear side.
12-2
CONNECTION BOARD (T-130)
As T-130 is PCB which is connecting CPU BOARD and other PCBs, when receiving, the
signals that come from NBDP receiver pass active filter consisted of IC5, IC6, IC7, IC8 and
then, as it is made square wave as clipping through U5, DOT/PATTERN signal is generated.
When receiving, 1.7kHz
±
85Hz signals are generated through DM1 and then it is delivered
to SRG-3150DN
12-3
NBDP RECEIVING UNIT (T-132)
T-132 PCB is NBDP receiving unit which consists of frequency filter and amplifier, MIXER,
ATT, AGC, B.K control circuit. After the signals received through MF/HF Antenna amplify
with wide amplifier, it is divided into two parts through SPLITTER (SP1)
①
Among them, one of RF signal goes through the selected bandpass filter and mixes
with the local signal on (IC2, I). And it passes by (XL1,2,3) and is converted to IF signal.
Finally the IF signal and BFO will create the demodulated signal on (IC3) and transfer
it to T-130 board.
②
The other RF signal goes through Impedance matching circuit and it is transferred to
the antenna connector of (SRG-150DN/250DN) W/K.
12-4
LOCAL SYNTHESIZE BOARD (T-133)
T-133 board creates 1
’
st (F
R
+49.456.7MHz) through 14MHz OCXO(Oven-Controlled Crystal
Oscillator), PLL(Phase Lock Loop) circuit and (DM2, IC9, U1, VCO1). And it creates 2
’
nd
49MHz using (T4,T5,T2,T3, Q5,7) and creates BFO(456.7KHz) through DDS IC(DM1).
12-5
POWER CIRCUIT (T-025)
Power circuit consists of constant voltage circuit. And while power on, it makes ON main
power DC 24V, convert constant v12V, +8V, +5V.
