Orban OPTIMOD-FM 8500S Operating Manual page 262

4-10
MAINTENANCE
H) Repeat steps (C) through (G) for the right channel.
5. Check distortion performance of Analog I/O.
A) Verify 8500S software controls are set to their default settings. (Refer to page
4-7.)
B) Be sure you are still in B
+17.0 dB.
C) Set the AO 100% control to +20 dBu.
D) Connect a THD analyzer to the Left Analog Output XLR connector. Set the
THD analyzer's bandwidth to 22 kHz.
E) Connect the oscillator to the Left Analog Input XLR connector. Set its fre-
quency to 50 Hz and its output level to +10 dBu. This should produce a level
of approximately +18 dBu at the 8500S's output.
F) For each frequency used to measure THD, adjust the output level of the oscil-
lator to make the C
the output level of the oscillator at higher frequencies to compensate for the
pre-emphasis boost in the 8500S. As the frequency increases, you will have to
reduce the output level of the generator to follow the 75μs deemphasis curve.
At 15 kHz, you should have to reduce the output of the generator to ap-
proximately –7 dBu.
G) Measure the THD+N at the frequency levels listed below.
Frequency
50 Hz
100 Hz
400 Hz
1 kHz
2.5 kHz
5 kHz
7.5 kHz
10 kHz
15 kHz
H) Repeat the above measurements for the right channel. Connect the oscillator
to the right analog input and the distortion analyzer to the right analog out-
put.
I) Disconnect the oscillator and THD analyzer from the 8500S.
6. Test Digital Sample Rate Converter (Receiver).
A) Verify 8500S software controls are set to their default settings. (Refer to page
4-7.)
B) Be sure you are still in B
C) Navigate to Setup > I/O C
mode [see step (3.F)] and set the B
YPASS
meter on the 8500S read 100. You will have to reduce
OMP
THD+N Typical
0.015%
0.015%
0.015%
0.015%
0.015%
0.015%
0.015%
0.015%
0.015%
mode [see step (3.F)].
YPASS
> D I C
ALIB IG N ALIB
ORBAN MODEL 8500S
THD+N Maximum
0.03%
0.03%
0.03%
0.03%
0.03%
0.03%
0.03%
0.03%
0.03%
.
G to
YPASS AIN