50
©2011 Broadcast Electronics
AUTOMATIC RANGING CIRCUIT OPERATION. The automatic ranging circuit provides expanded scale meter
indication for low level modulation signals. During low level signal conditions, the output of gain switch
amplifier U1A insufficiently charges capacitor C4 through diode D1.
This minimal charge on C4 is applied to gain switch comparator U1B which outputs a positive voltage to bias
gain switch Q7 OFF and illuminate indicator DS11. With Q7 OFF (open), expanded scale calibration control R28
operates as a feedback resistor for automatic ranging amplifier U1C. This converts the circuit into an inverting
amplifier with a gain of 10.
7.4.5
VOLTAGE REGULATOR CIRCUITS.
The metering circuit board contains four voltage regulator circuits which convert the FX-50/E primary operating
voltages to potentials required for circuit board operation. All regulators are equipped with overload protection,
thermal overload protection, and current limiting circuits.
Voltage regulator circuit U15 converts a -20 volt potential into a -15 volt source. This -15 volts is also applied to
the input of regulator circuit U16 which provides a -5 volt potential. Voltage regulator circuit U14 converts a
+20 volt potential into a +15 volt source. Finally, voltage regulator circuit U22 converts the +30 volt
unregulated voltage (B+) to provide a +24 volt potential.
7.5
MAINTENANCE
This section provides maintenance information, electrical adjustment procedures and troubleshooting
information for the metering circuit board assembly.
7.5.1
ELECTRICAL ADJUSTMENTS.
REQUIRED EQUIPMENT. The following tools and equipment are required for electrical adjustment procedures.
A. Insulated adjustment tool, shipped with the exciter (P/N 407-0083).
B. Digital voltmeter, Fluke 75 or equivalent.
C. Low distortion audio generator.
D. Calibrated oscilloscope.
METER CALIBRATE CONTROL (R56). Potentiometer R56 on the metering circuit board adjusts the multimeter
circuitry for an accurate indication in the test meter mode. To adjust R56, refer to Figure 7-3 as required and
proceed as follows.
Procedure. To adjust meter calibration control R56, proceed as follows:
WARNING
DISCONNECT EXCITER PRIMARY POWER BEFORE
PROCEEDING.
WARNING
A. Disconnect the exciter primary power.
B. Remove the top-cover. Connect an external voltmeter and exciter test probe to test point TP1 (+5V).
C. Apply exciter primary power and operate the test switch/indicator on the metering circuit board to
illuminate the switch/indicator.
Содержание FX-50
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Страница 20: ...8 2011 Broadcast Electronics Figure 2 1 FX 50 E REAR PANEL CONNECTIONS SHEET 1 OR 2 ...
Страница 21: ...9 2011 Broadcast Electronics Figure 2 1 FX 50 E REAR PANEL CONNECTIONS SHEET 2 OR 2 ...
Страница 32: ...20 2011 Broadcast Electronics Figure 3 1 FX 50 E CONTROLS AND INDICATORS ...
Страница 35: ...23 2011 Broadcast Electronics Figure 4 1 FX 50 E OVERALL SIMPLIFIED SCHEMATIC ...
Страница 40: ...28 2011 Broadcast Electronics Figure 5 1 FX 50 E ASSEMBLY ...
Страница 46: ...34 2011 Broadcast Electronics Figure 6 1 CONTROL CIRCUITRY SIMPLIFIED SCHEMATIC ...
Страница 49: ...37 2011 Broadcast Electronics Figure 6 2 POWER SUPPLY SIMPLIFIED SCHEMATIC DIAGRAM ...
Страница 53: ...41 2011 Broadcast Electronics Figure 6 4 PARALLEL LOAD CONNECTION ...
Страница 56: ...44 2011 Broadcast Electronics Figure 6 5 NO PA VOLTAGE TO THE RF AMPLIFIER ...
Страница 58: ...46 2011 Broadcast Electronics Figure 7 1 METERING CIRCUIT REMOVAL AND INSTALLATION DIAGRAM ...
Страница 60: ...48 2011 Broadcast Electronics Figure 7 2 METTERING BOARD SIMPLIFIED SCHEMATIC ...
Страница 68: ...56 2011 Broadcast Electronics Figure 8 1 MODULATED OSCILLATOR SIMPLIFIED SCHEMATIC DIAGRAM ...
Страница 74: ...62 2011 Broadcast Electronics Figure 9 1 AFC PLL CIRCUIT BOARD SIMPLIFIED SCHEMATIC ...
Страница 81: ...69 2011 Broadcast Electronics Table 9 2 FREQUENCY SYNTHESIZER PROGRAMMING ...
Страница 84: ...72 2011 Broadcast Electronics Figure 9 4 NO RF OUTPUT LOCK IS EXTINGUISHED ...
Страница 85: ...73 2011 Broadcast Electronics Figure 9 5 NO MODULATION LOCK INDICATOR ILLUMINATED ...
Страница 89: ...77 2011 Broadcast Electronics Figure 10 1 RF AMPLIFIER SIMPLIFIED SCHEMATIC ...
Страница 92: ...80 2011 Broadcast Electronics Figure 10 2 RF AMPLIFIER CIRCUIT BOARD CONTROLS ...
Страница 95: ...83 2011 Broadcast Electronics Figure 10 3 RF AMPLIFIER TROUBLESHOOTING INFORMATION ...
Страница 100: ...88 2011 Broadcast Electronics Figure 11 1 SLAVE FM BOOSTER SIMPLIIFED SCHEMATIC ...
Страница 101: ...89 2011 Broadcast Electronics Figure 11 2 MASTER FM BOOSTER SIMPLIFIED SCHEMATIC ...
Страница 161: ...149 2011 Broadcast Electronics Figure 14 1 OPTIONAL LOW PASS FILTER ASSEMBLY ...
Страница 162: ...150 2011 Broadcast Electronics Figure 14 2 EXCITER FRONT RAIL MOUNTING APPLICATIONS ...
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