3-8
WRT-808A (U)
3-2-7. Input Level Control Check
Equipment and Tools
DC power supply
DC output Voltage:
+
3.0
±
0.1 Vdc
DC ammeter
Audio analyzer
Modulation analyzer
MEASUREMENT:
FM
MEASUREMENT RANGE: AUTO or
±
40 kHz
HPF:
50 Hz
LPF:
15 kHz or 20 kHz
DE EMPHASIS:
50
u
s
Oscilloscope
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 channel
select switches (S504 and S505).
U64 model: 65-01 channel (776.125 MHz)
U66 model: 67-01 channel (788.125 MHz)
U68 model: 69-01 channel (800.125 MHz)
RF power output switch (S401): 50 mW
Input LEVEL control (RV101):
“
_
60”(0 dB attenuation) Turn the RV101 clockwise fully.
Procedure
(1) Connect the audio analyzer (level meter) to the AF OUT
connector on 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 (CN101) from audio analyzer (oscilla-
tor).
(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) Turn the RV101 (Input LEVEL control) counterclock-
wise fully.
(7) Check that audio analyzer (level meter) reading is
_
26
dB. (Indication level is
_
26
dB as compared with
the read level of procedure (5) above.)
+
2
_
1
+
2
_
1
Switch and Control Setting
The following setting is to be perform with the channel se-
lect switches (S504 and S505).
Transmitting Channel setting:
U64 model: 65-01 channel (776.125 MHz)
U66 model: 67-01 channel (788.125 MHz)
U68 model: 69-01 channel (800.125 MHz)
RF power output switch (S401): 50 mW
Input LEVEL control (RV101): “
_
60” (0 dB attenuation)
Turn the RV101 clockwise
fully.
Procedure
(1) Connect the audio analyzer (distortion analyzer) to the
AF OUT connector on the modulation analyzer.
(2) Set the audio analyzer to distortion measurement (dis-
tortion mode).
(3) Input 1 kHz,
_
60 dBV (
_
57.8 dBm) signal to the MIC
input connector (CN101) from audio analyzer (oscilla-
tor).
(4) Check that the distortion analyzer reading is less than
0.90 %.
(5) Input 1 kHz,
_
24 dBV (
_
21.8 dBm) signal to the MIC
input connector (CN101).
(6) Check that the distortion analyzer reading is less than
0.9 %.
