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7.2 GENERADOR ESTÉREO SC100
Protocolo para ajuste fino
Este generador, por su tecnología esencialmente
digital con sobremuestreo 16x, no requiere ajus-
tes, aún luego de muchos años. Pero si desea ha-
cer una verificación técnica de las especificacio-
nes, le damos las instrucciones a continuación. Las
mismas están redactadas en inglés.
SI USTED NO CONOCE A FONDO LA TEORIA
DEL MATRIZADO ESTEREO MPX O NO CUEN-
TA CON INSTRUMENTAL ADECUADO, ROGA-
MOS NO ENCARAR ESTE TRABAJO.
7.2.1
TEST POINTS DIAGRAM
components side
7.2.2
ADJUST PILOT LEVEL
a) Connect to ground the test point TP1 (R246) in
order to eliminate the 19 KHz pilot tone. Use a
good DC-20 Mhz calibrated oscilloscope at the
MPX output connector. Using the display control,
select the MPX output to 4 V peak to peak. Con-
nect a sine wave generator at the LEFT input of the
audio processor, at 1 Khz, + 4 dBm output. Verify
that the output waveform looks like FIG-1.
procesador para radiodifusión - SOLIDYNE 562dsp
a)
Replace the audio generator at the processors Left
input for audio program (music or voice). Please ca-
refully take note of this peak to peak value; let name
it Xpp.
b) Disconnect the audio program from the LEFT input
and disconnect the ground of the test point TP1.
Then, the 19 Khz pilot tone will appear.
c) With the oscilloscope measure the peak to peak va-
lue of the 19 Khz pilot tone; let name it Ppp. The per-
centage level of pilot tone will be:
Pilot Level [%] = 100.Ppp/Xpp
d) Using the control P4, adjust Ppp to the desired value
(normally 9 to 11 % is a good value)
Note: If you have a Solidyne VA16 modulation monitor or BE-
LAR FMS-2 measurement set, you will be able to measure pilot
tone level from on-air transmission and you can correct it using
P4.
7.2.3
PILOT PHASE ADJUSTMENT
This method is an absolute system not dependent
from the calibration of the Modulation Monitor. You
will need a very good DC-20 Mhz oscilloscope
(Tektronix preferred) with vertical 10x undistorted
span. Proceed:
a) Change the SC-100 PHASE jumper (JF1) from the
Normal "N" position to calibrate "C" position.
b) Input a sine wave generator at 1 KHz, +4 dBm, at
Left Channel of the audio processor. Adjust the level
of wave generator to get 4 Vpp MPX output.
c) Connect the oscilloscope to the MPX output in mode
DC.
Use the sine wave output of audio generator, to syn-
chronize the oscilloscope sweep. Adjust the sweep to
5 uS/Div. Modify with trigger level, the center of the
wave in order to have it centered at screen.
Adjust vertical sensitivity to 50 mV/Div. You must get
a signal like FIG-2.
If not, you must do a slight change in the frequency
knob of the audio generator in order to avoid integral
multiplication factors that do not allow you to appreci-
ate the correct image.
Calibrate the P3 Phase Control to get zero phase er-
ror. The phase error is indicated by the tilt of the ima-
ginary line between H1-H2 points. When this line is
full horizontal, the phase is correct.
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