Tuner Section - Sherwood R-772 Service Manual

Measuring methods in confirmity with IEC standard 315
Measurements condition FM : Radio frequency = 98.1MHz, Audio frequency = 1kHz
Reference level = 1mV on ( 75ohms , 300ohms )
Deviation : MONO = ±75kHz, Stereo = ±67.5kHz±7.5kHz (A)
MONO = ±40kHz, Stereo = ±40kHz±7.5kHz (RDS)
Test Point : TP 1 = 90.1MHz, TP 2 = 98.1MHz, TP 3 = 106.1MHz (100KHz STEP(A), 50KHz STEP(RDS))
Power supply : 120V/60Hz (A), 230V/50Hz (RDS)
FM SECTION
NO.
1
TUNING RANGE
STEP (A)
STEP (RDS)
2 USABLE SENSITIVITY
S/N = 30dB (A)
S/N = 26dB (RDS)
3
AUTO STOP LEVEL
4
S/N RATIO
IHF-A
5 T. H. D
6 OVER LOAD DISTORTION(120dBu, 75kHz)
7 STEREO SEPARTION
(MAIN 90%(A), 53.5%(RDS), PILOT 10%)
EXT 19kHz FILTER
8
FREQUENCY RESPONSE(75us(A), 50us(RDS) -3dB)
9
IF REJECTION (A)
IF REJECTION (RDS)
10 IMAGE REJECTION (A)
IMAGE REJECTION
11 AM SUPRESSION(AT AM 30% 1kHz)
12
OUTPUT LEVEL MONO (A)
OUTPUT LEVEL MONO
13
RDS SENSITIVITY (RDS ONLY)

TUNER SECTION

DESCRIPTION
(RDS)
(RDS)
Filter = B.P.F at STEREO MONO
UNIT
LOW ~ HIGH
AUTO/Man.
AUTO/Man.
TP 1
TP 2
TP 3
MONO
STEREO
MONO 1kHz
STEREO 1kHz
MONO
250Hz
1kHz
6.3kHz
TP 2
TP 1
TP 3
TP 2 mV rms
TP 2
7
LIMIT L/R NOMINAL L/R
87.5~108
MHz
kHz 100/100
kHz 50/50
dBu
12
dBu
12
dBu
12
dBu 25±6 25±8
dBu 55
dBu 50
0.7
1.0
dB
2
dBu
30
dBu
30
dBu
20
Hz 60~8K 70~7K
65
dB
75
dB
20
dB
75
dB
40
500±100 500±150
280±100 280±150
dBf
30
15
15
15
50
45
1.2
1.5
3
25
25
15
60
70
18
70
35
35