Simplicity 708 Manual de Instruções

OPERATING AND MAINTENANCE INSTRUCTION MANUAL MODEL 708 FM-STEREO GENERATOR __________

— — 8Voltage Selector A mains voltage selector switch is located beneath the top cover of the unit, adjacent to the AC mains connector on the c

— — 9Balanced Inputs A balanced program audio feed to the 708 will use both the + and the – terminals, plus the associated G (ground) terminal

— — 10PRE-EMPHASIS SELECTION The Model 708 Stereo Generator supports the 75-microsecond FM broadcasting pre-emphasis standard common to the West

— — 11COMPOSITE OUTPUT The unbalanced COMPOSITE OUTPUT of the Inovonics 708 has a resistive source impedance of 75 ohms. This permits runs of m

— — 12Section III SETUP AND OPERATION PANEL CONTROLS AND INDICATORS A brief description of the front-panel controls and indicators is given her

— — 13 PILOT The PILOT switch lets the user manually turn off the 19kHz stereo pilot for certain tests. Since the 19kHz pilot is necessary for

— — 14 COMPOSITE PROCESSING PEAK VALUE OF CLIPPING PRODUCTS OUT >60dB below 100% 1dB 50dB below 100% 2dB 45dB below 100% 3dB 40dB b

— — 15(10X) circuit gain re-scales the measurements for these lower-level signals. For these measurements, the 100% marking should be read as 1

— — 16to about 5%, SCA subcarriers to 10%. Again, the 100% mark on the meter should be read as 10% for these measurements. Output Pre-check The

— — 17 4. Switch the Modulation Monitor to display the injection level of the 19kHz stereo pilot and confirm 9% injection. Touch-up the PILOT

—– USER’S RECORD —– Model 708 - Serial No. _______ Date Purchased _____________ Warranty Card Mailed — ¨ OPERATING AND MAINTENANCE INSTRUCTION

— — 18 Out-of-Band Components Simple clipping of a symmetrical waveform will invariably generate odd-order harmonics of the fundamental frequenc

— — 19 Figure 4c - 2dB Clipping Figure 4d - 3dB Clipping

— — 20Section IV CALIBRATION “Routine” calibration of the Model 708 Stereo Generator is never required, its digital-synthesis circuitry is sim

— — 21 Input Level Set 1. Preset the 708 front-panel switches as follows: POWER — ON MODE — MONO PILOT — OFF O’SHOOT COMP. — OUT PRE-EMPHASIS

— — 223. When the Audio Generator has been fine-tuned to null the right channel, adjust R116 (next to IC31) for a null in the left channel filt

— — 23 Input Level Calibration NOTE: This portion of 708 calibration must follow the preceding Crosstalk Trim procedure directly. 1. Re-apply

— — 24 8. Reset the COMPOSITE PROCESSING control to the full-counterclockwise OUT position. NOTE: when composite clipping is turned off, fro

— — 25transmission system; for instance, in a “composite” STL, or even in a long run of coax cable. The following procedure leaves the 708 adjus

— — 26Section V CIRCUIT DESCRIPTIONS This section details the circuitry of the Inovonics Model 708 FM Stereo Generator. Circuit descriptions r

— — 27filtering, helped define the signal peak amplitude. Even a fully phase-corrected filter will exhibit overshoots, and a 7-pole “elliptic”

— — 1TABLE OF CONTENTS Section I - INTRODUCTION Model 708 Product Description ...

— — 28Components in the right channel filter have fixed values. The resonant frequency of each of the left channel legs is variable over a smal

— — 29Digital synthesis of the composite waveform is similar to the generation of the Stereo Pilot previously discussed, but with sinusoidal com

— — 30Output Filter Since all components of the composite output are digitally synthesized at a 608kHz rate, only a simple filter is required t

— — 31comprise the Model 708 display. The front-panel meter is scaled both in percent-modulation and in dB. This is similar to a standard VU m

— — 32

— — 33Section VI APPENDIX The following section of this Manual contains Parts Lists for the Inovonics 708 Stereo Generator, Schematic Dia- gram

— — 34PARTS LIST EXPLANATION OF PARTS LISTINGS This section contains listings of component parts used in the Inovonics 708 FM-Stereo Generator.

— — 35CR10 Diode, Zener, 22V; (open mfgr.) 1N5251 F1 Fuseholder, PC-mounting; Littlefuse 345-101-010 with 345-101-020 Cap for ¼-inch (U.S.) fu

— — 36 J1 AC Mains Connector, PC-mounting; Switchcraft EAC303 J2 6-Position Barrier Block; PCD Co. ELFH06210 PC-mounting header with ELFP06210

— — 37MAIL-ORDER COMPONENT SUPPLIERS The following electronic component distributors have proven to be reputable suppliers of both large and sma

— — 2Implications of Composite Processing ...17 Pilot Modulation - O

— — 3Section I INTRODUCTION MODEL 708 PRODUCT DESCRIPTION General Inovonics introduced its first FM-Stereo Generator in 1992. The original Mo

— — 4transmission. This noise is generally worse for listeners who are some distance from the broadcasting station. If a low frequency tone of,

— — 5MODEL 708 TECHNICAL SPECIFICATIONS Frequency Response (with pre-emphasis turned OFF, or through appropriate de-emphasis network): ±0.5dB, 2

— — 6Figure 1 - Block Diagram, Model 708 FM-Stereo Generator

— — 7Section II INSTALLATION UNPACKING AND INSPECTION Immediately upon receipt of the equipment, inspect carefully for any shipping damage. If