Instruction manual

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Section III

SETUP AND OPERATION

PANEL CONTROLS AND INDICATORS

A brief description of the front-panel controls and indicators is given

here. Do scan this section to at least verify that our terminology agrees

with yours.

PLEASE NOTE that all front-panel multi-turn trim controls require

fifteen to twenty complete rotations of the adjusting screw to cover their

total operating range. Depending on the trim-pot manufacturer, the end

of the range may, or may not, be identified by a “click-click” sound or

other audible/tactile sensation.

INPUT GAIN

These two controls at the far-right end of the front

panel adjust the 708’s input sensitivity for the nominal

program level applied to the LEFT and RIGHT channel

PROGRAM LINE INPUT barrier strip terminals on the

rear panel. The controls have a 15dB range which is

multiplied by input gain range jumpering to an input

acceptance range of 30dB (see Page 9). The INPUT

GAIN controls are adjusted so that the 100%-

modulation “ceiling” imposed by Model 708 internal

circuitry coincides with the input program peak level

which corresponds to 100% modulation.

PRE-EMPHASIS

System pre-emphasis is imparted by the Stereo

Generator in most situations. With the front-panel

PRE-EMPHASIS switch IN, the selected characteristic

(see Page 10) is enabled and the attendant green LED

will light. If, on the other hand, pre-emphasized audio

is applied to the 708, the switch should be set to the

OUT position to avoid “double” pre-emphasis. This

alternate mode is indicated by the red LED.

O’SHOOT COMP.

The Model 708 incorporates a patented overshoot

compensation circuit which inhibits overshoots in the

primary 16kHz audio low-pass filter sections. The

switch is normally left in the IN position, indicated by

the green LED. Compensation may be switched OUT

for system tests which require carrier deviation in

excess of 100% (maximum); this will light the red LED.

The yellow LED to the right of the green one displays

circuit action and will flash almost continuously when

“bright” music is being broadcast.