Sony WRT-822B, Service Manual

Page: 17 / 46

3-9
WRT-822B
3-2-8. Frequency Characteristics Check
Equipment and Tools
DC power supply
DC output Voltage:
+
3.0
±
0.1 V dc
DC ammeter
Audio analyzer
Modulation analyzer
MEASUREMENT: FM
MEASUREMENT RANGE:
±
40 kHz
HPF: 50 Hz
LPF: 15 kHz or 20 kHz
DE EMPHASIS: 50
µ
s
Oscilloscope
MIC input cable (See page 3-1.)
MM-SMA (J) connector (Part No. J-6402-480-A)
SMA-BNC (J) connector (Part No. J-6402-490-A)
Connections
Same as “3-2-6. Distortion Ratio Check”.
Switch and Control Setting
The following setting is to be perform with the SET switch
(S402) , “
+
” switch (S400) and “
_
” switch(S401).
Transmitting Channel setting:
CE21 model; Group 00, 21-01 channel (470.125 MHz)
CE33 model; Group 00, 33-01 channel (566.125 MHz)
CE62 model; Group 00, 62-01 channel (798.125 MHz)
CE67 model; Group 00, 67-01 channel (838.125 MHz)
U14 model; 14-01 channel (470.125 MHz)
U30 model; 30-01 channel (566.125 MHz)
U62 model; 62-01 channel (758.125 MHz)
U66 model; 66-01 channel (782.125 MHz)
Attenuation setting: 0 dB
Accumulated time setting: “Don't Care”
Procedure
(1) Connect the audio analyzer (level meter) to the AF OUT
connector for the modulation analyzer.
(2) Set the audio analyzer to level meter mode.
(3) Input 1 kHz,
_
60 dBV (
_
57.8 dBm) signal to the Mic
input connector (SMC9-4P) with Mic input cable from
audio analyzer (oscillator).
(4) Reads the indication on the audio analyzer (level meter) .
(5) Set the SENSITIVITY on the audio analyzer (level
meter) so that the audio analyzer (level meter) reads 0
dB.
(6) Switch the oscillation frequency for the audio analyzer
(oscillator) from 1 kHz to 100 Hz.
(7) Check that audio analyzer (level meter) reading is 0
±
1.0 dB.
(8) Next, switch the oscillation frequency for the audio ana-
lyzer (oscillator) from 100 Hz to 10 kHz.
(9) Check that the reading for the audio analyzer (level
meter) is 0.5
±
2.0 dB.