User's Manual - Crown Broadcast

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3.2 Power Switches3.2.1 DC BreakerThe DC breaker, on the rear panel, must be on (up) for transmitter operation, even whenusing AC power. Electrically, the DC breaker is located immediately after diodes which isolatethe DC and AC power supplies.3.2.2 Power SwitchThe main on/off power switch controls both the 120/240 VAC and the DC battery power input.3.2.3 Carrier SwitchThis switch controls power to the RF amplifiers and supplies a logic high to the voltageregulator board, which enables the supply for the RF driver. In addition, the Carrier Switchcontrols the operating voltage needed by the switching power regulator.A "Lock Fault" or a low pin 17 (/Carrier Off) on the Remote I/O connector will hold the carrieroff. (See section 2.12.)Carrier SwitchIllustration 3–3 Front Panel Carrier Switch3-4 FM50/FM150/FM300 User’s <strong>Manual</strong>
3.3 Front Panel Bar-Dot DisplaysBar-dot LEDs show audio input levels, wideband and highband audio gain control, andmodulation percentage. Resolution for the gain control and modulation displays is increasedover a conventional bar-graph display using dither enhancement which modulates thebrightness of the LED to give the effect of a fade from dot to dot. (See section 4.7.)3.3.1 Audio Processor InputTwo vertical, moving-dot displays for the left and right channels indicate the relative audiolevels, in 3 dB steps, at the input of the audio processor. Under normal operating conditions,the left and right Audio Processor indicators will be active, indicating the relative audio inputlevel after the Input Gain switches. During program pauses, the red Low LED will light.The translator configuration shows relative audio levels from the included receiver.3.3.2 Highband and Wideband DisplayDuring audio processing, the moving-dot displays indicate the amount of gain control forbroadband (Wide) and pre-emphasized (High) audio.As long as program material causes activity of the Wideband green indicators, determinedby the program source level and Input Gain switches, the transmitter will be fully modulated.(See section 3.4.)The Wideband indicator shows short-term “syllabic-rate” expansion and gain reductionaround a long-term (several seconds) average gain set. In the translator configuration, theWideband indicator also shows relative RF signal strength.Program material and the setting of the Processing control determine the magnitude of theshort-term expansion and compression (the rapid left and right movement of the greenlight).High-frequency program content affects the activity of the Highband indicator. With 75–µsecpre-emphasis, Highband processing begins at about 2 kHz and increases as the audio frequencyincreases. Some programs, especially speech, may show no activity while somemusic programs may show a great deal of activity.3.3.3 Modulation DisplayA 10–segment, vertical peak-and-hold, bar graph displays the peak modulation percentage.A reading of “100” coincides with 75 kHz deviation. The display holds briefly (about 0.1 seconds)after the peak. The “Pilot” indicator illuminates when the transmitter is in the stereomode.To verify the actual (or more precise) modulation percentage, connect a certified modulationmonitor to the RF monitor jack on the rear panel.Operation3-5
Page 1 and 2: FM30/FM150/FM300 Broadcast Transmit
Page 3 and 4: ContentsSection 1- Getting Acquaint
Page 5 and 6: Section 5-Adjustments and Tests 5-1
Page 7 and 8: Section 1—Getting AcquaintedThis
Page 9 and 10: 1.2 Applications and OptionsCrown t
Page 11 and 12: 1.2.4 TranslatorA receiver configur
Page 13 and 14: 1.3 Transmitter/Exciter Specificati
Page 15 and 16: Note: We set voltage and ampere req
Page 17 and 18: Section 2—InstallationThis sectio
Page 19 and 20: Illustration 2-1 Removing the Power
Page 21 and 22: 2.2.3 Battery PowerYour transmitter
Page 23 and 24: 2.3.1 Modulation CompensatorThe Mod
Page 25 and 26: Freq. 74-90 Freq. 88-108 SW1 SW2 Fr
Page 27 and 28: Freq. 74-90 Freq. 88-108 SW1 SW2 Fr
Page 29 and 30: 2.6 Audio Input ConnectionsAttach a
Page 31 and 32: Illustration 2-16 Composite In and
Page 33 and 34: Pin Number Function1. Ground2. FMV
Page 35 and 36: Section 3—OperationThis section p
Page 37: 3. Verify the following:A. The bott
Page 41 and 42: 3.7 RF Output ControlSet this contr
Page 43 and 44: Section 4—Principles of Operation
Page 45 and 46: 4.2 Audio Processor/Stereo Generato
Page 47 and 48: Processed, pre-emphasized left and
Page 49 and 50: 4.5 Metering CircuitThe ALC and met
Page 51 and 52: Motherboard Jumper Configuration Ch
Page 53 and 54: 4.8 Voltage Regulator Circuit Board
Page 55 and 56: 4.11 RF Driver (FM150/FM300)The RF
Page 57 and 58: 4.15 Receiver Circuit Board OptionT
Page 59 and 60: Section 5—Adjustments and TestsTh
Page 61 and 62: 5.2.2 Composite OutputYou can make
Page 63 and 64: 5.4.3 SWR CalibrateWhen the Carrier
Page 65 and 66: 5.9 Performance VerificationMeasure
Page 67 and 68: 5.15 Audio DistortionMake distortio
Page 69 and 70: Section 6—Reference DrawingsThe i
Page 71 and 72: MeteringCircuitAudio ProcessorSecti
Page 73 and 74: 6.2 Board Layout and SchematicsIllu
Page 75 and 76: 65581 234571234DWG. NO.REV.56789510
Page 77 and 78: 987654321123456789321121234123DWG.
Page 79 and 80: 23212132543215432154321543215432143
Page 81 and 82: Illustration 6-9 FM Display BoardFM
Page 83 and 84: Illustration 6-10 FM Voltage Regula
Page 85 and 86: Illustration 6-11 FM Power Regulato
Page 87 and 88: R19Illustration 6-12 FM Power Ampli
Page 89 and 90:
Illustration 6-13 FM Low Pass Filte
Page 91 and 92:
Illustration 6-14 FM RF DriverFM30/
Page 93 and 94:
1 2 3 4 5 6REVISION HISTORYAPPROVAL
Page 95 and 96:
Section 7—Service and SupportWe u
Page 97 and 98:
Crown Broadcast Three Year Limited
Page 99 and 100:
Factory Service InstructionsTo obta
Page 101 and 102:
Transmitter Output EfficiencyRF Pow
Page 103 and 104:
GlossaryThe following pages define
Page 105 and 106:
FETFrequency SynthesizerFMonFSKGain
Page 107 and 108:
Symbols19-kHzlevel adjustment 5-3ph
Page 109 and 110:
M (continued)Monooperation 2-13, 3-
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User's Manual - Crown Broadcast

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