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page 8
RET-041 Instructions
95307-000-01 6/87
7) Turn the HF EQ control fully clockwise.
This instruction supersedes the settings shown in Fig. 4-6 " Recommended Initial Control
Adjustments ") on page 4-7 of the Third Edition of the 9100A Operating Manual. You
may wish to note this change on that figure.
8) Attach the supplied " Special Modification " label to the rear panel.
) Install NRSC de-emphasis circuit for monitoring.
The ACC-5 Monitor Rolloff Filters supplied with 9100A/1 units were designed to comple
ment the original GREEN module. When the BLUE module is used, a simple de-emphasis
circuit can be placed between the audio output of the modulation monitor and the input
of the monitor amplifier to provide complementary 75gs de-emphasis. For a more pre
cise simulation of a " standard " NRSC receiver including a 10kHz notch filter to reduce
any audible artifacts that might result from ringing introduced by the very sharp 10kHz
low-pass filter, and to eliminate 10kHz whistles encountered in off-air monitoring), we
recommend our ACC-023 NRSC Monitor Rolloff Filter.
See Fig. 5 for a schematic of the simplified rolloff filter and information about installing
it the parts needed are included in this kit). Note that the frequency response of this filter
is correct only when both its source and load impedances are approximately 600 ohms,
and that resistors or pads may have to added to achieve this.
Monitor Rolloff Filter
Monitor Amp or D.A.
Modulation Monitor
Fig. 5: NRSC Simplified 75ps Monitor Rolloff Filter Schematic
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