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is a 100-W input type if R201 is removed and R202 is installed.
(2) Bandpass Filter
The RF video output of IC202 is a double sideband amplitude
modulation of the 59.75-MHz picture carrier. In order to limit the
bandwidth of the RF video output, the output goes through FL201 (SAW
(Surface Acoustic Wave) bandpass filter). FL201 has a flat bandpass
response from 55.25 MHz to 59.75 MHz. Because the picture carrier
frequency is 59.75 MHz, the RF video output becomes a lower-sideband
AM signal after FL201. Installed before and after FL201 are RF
amplifiers (IC207 and IC208).
(3) Up Conversion
An oscillator circuit (X203 and Q205) generates an RF signal of
52.75 MHz. The 8th harmonic of this RF signal is amplified to give
an RF signal of 422 MHz (52.75 MHz x 8). This 422-MHz signal goes
through FL212 (422-MHz bandpass filter) and IC212 (RF amplifier) and
goes to DBM201 (double balanced mixer).
DBM201 mixes the 59.75-MHz RF video signal from IC208 with the
422-MHz signal from IC212 and gives two RF video signals of
different frequencies, 362.25 MHz and 481.75 MHz. The 481.75-MHz RF
video signal goes through FL209, IC209 (RF amplifier) and FL210.
FL209 and FL210 are 480-MHz bandpass filters that gives a pass band
of approximately 10 MHz.
NOTE: A number of changes were done on the above 480-MHz bandpass
amplifier circuit. The description applies to the first
configuration before these changes.
Page 14
Feb 20/2002
Matsushita Avionics Systems Corporation
COMPONENT MAINTENANCE MANUAL
PART NUMBER RD-AA5002 SERIES
23-32-47
MIXER
FL201
55.25-59.75MHz
MIXER
PLL FREQUENCY
SYNTHESIZER
+5V
-5V
LPF
300MHz
VIDEO IN
RF VIDEO
DT
CK
LD
POWER CONTROL
59.75 MHz
RF MODULATOR
MODULATION
VIDEO
OSCILLATOR
CARRIER
WHITE
CLAMP CLIP
IC202
BUFFER
50/100W
SAW
BPF
OSC X8
MULTIPLIER
FL212
422MHz
BPF
52.75 MHz
FL209
480MHz
BPF
422MHz
59.75 MHz
FL210
480MHz
BPF
PROGRAMMABLE
UHF
OSCILLATOR
OUTPUT
50W
DATA
CLOCK
LOCK DETECT
VOLTAGE
REGULATOR
VOLTAGE
REGULATOR
VOLTAGE
REGULATOR
SWITCH
+5VS
+24V
+32V
+8V
-9V
PC
IC201
X201
481.75MHz
IC207 IC208 DBM201 IC209
Q205 Q206 IC212
DBM202
VR201
VR202 FL211 IC210
IC202
IC205
IC212
Q203/204 IC211
IC204
Q207/208
FOR IC201
X203
X202
4 MHz
THE PREFIX A2 FOR THE EQUIPMENT DESIGNATORS IS NOT SHOWN IN THE ABOVE
ILLUSTRATION.
BLOCK DIAGRAM OF MODULATOR CARD ASSEMBLY (A2)
Figure 4
Page 14.01
Feb 20/2002
Matsushita Avionics Systems Corporation
COMPONENT MAINTENANCE MANUAL
PART NUMBER RD-AA5002 SERIES
23-32-47
(4) UHF Oscillator and Frequency Synthesizer
D202 (varactor diode), a printed coil (part of the printed circuit
card) and Q203 make a voltage controlled UHF oscillator (VCO). D202
is reverse-biased to give a capacitance. The capacitance of D202
changes with the bias voltage. Thus, the bias voltage changes the
frequency of the VCO.
IC204 is a programmable PLL (Phase-Locked Loop) frequency
synthesizer. Figure 5 shows its internal block diagram.
20 19 18 17 16 15 14 13 12 11
1 2 3 4 5 6 7 8 9 10
1/8 DRIVER
10-BIT MAIN COUNTER
5-BIT SLOW COUNTER
SELECTOR 19-BIT DATA LATCH
19-BIT
SHIFT REGISTER
OSC/10-BIT
DIVIDER
PHASE
TEST EN DATA CLK SW XIN XOUT GND PD2 PD1
FREF VCC FIN GND BIAS
BS1 BS2 BS3 BS4
BAND SELECT OUTPUT
1/32, 1/33
LD
AMP
COMPARATOR
PHASE DETECT OUTPUTS
IC204 PROGRAMMABLE PLL FREQUENCY SYNTHESIZER
Figure 5
X202 (4 MHz crystal unit) is connected across pins 6 and 7 of IC204.
Inside IC204, this 4-MHz signal is divided by 21 0, and becomes a
3.90625 kHz reference (Fref). The above-mentioned VCO output is
connected to pin 17 of IC204, in which the VCO output is frequencydivided
to Fin/N and compared with Fref. The PD1 and PD2 outputs of
IC204 are H if Fin/N leads Fref, or L if Fin/N lags Fref, or in a
high-impedance state if Fin/N is in phase with Fref.
Page 14.02
Feb 20/2002
Matsushita Avionics Systems Corporation
COMPONENT MAINTENANCE MANUAL
PART NUMBER RD-AA5002 SERIES
23-32-47
The PD1 and PD2 outputs control the bias voltage applied to D202
through a resistor-capacitor network and Q201. The +32V power from
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COMPONENT MAINTENANCE MANUAL Video Modulator Unit (VMU)(20)
