AMERITRON AL-572, Инструкция по эксплуатации

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Ameritron AL-572 Instruction Manual
9
voltage of D103, Q103 will move towards cut-off and the collector voltage will increase. Q103
functions as a current buffer for zener diode D103.
W
ATTMETER
C
IRCUIT
The AL-572 wattmeter circuit uses an accurate directional coupler followed by a true peak
detector circuit. This circuit will accurately determine the true peak envelope power (PEP) of
normal voice waveforms. If the load SWR is high, the true power reading will be obtained by
subtracting the reflected power from the forward power.
POWER SUPPLY
F
ILAMENT
S
UPPLY
The filament circuit of this amplifier satisfies all requirements of the tube manufacturer related to
tube performance and life. The filament voltage and inrush current are controlled by the power
transformer's internal resistance and impedance, filament choke resistance, filament wiring
resistance, and the step-start circuit. NEVER replace any circuit components or wiring with
substitute parts. This precaution will insure maximum life for the tube.
P
LATE
(HV) S
UPPLY
The plate supply uses a full wave doubler circuit with 200 amp surge rated diodes and a heavy
duty 21 pound transformer. Filtering is accomplished by a bank of high quality computer grade
capacitors totaling 26 mFd. Large 50k ohm, 7 watt bleeders are used for safety and superior
voltage equalization. The transformer allows user selection of fourteen different line voltages
(see the "
T
RANSFORMER
C
ONNECTIONS
" section on page 15 for details).
Power is supplied through "OFF-ON" switch S2. A 10 ohm resistor (R27) limits the line current
during the filter capacitor charge time to lower component stress. When the filter capacitor
charging current decreases sufficiently, RLY102 shorts the 10 ohm resistor. This applies full
power line voltage to the transformer. The 10 ohm resistor is protected from high-voltage supply
shorts by a 2A slow-blow fuse (F101) during start-up. If F101 or the 10 ohm resistor (R27) fails
the amplifier will not start. If F101 fails from a momentary HV to ground fault, meter protection
diode D117 may also fail. See the "
Metering Functions
" section that follows for more
information.
METERS
C
URRENT
M
ETER
(
PLATE AND GRID
)
The plate and grid current meter is located on the far left side of the front panel. This meter
indicates the plate current (Ip) on the right-hand meter scale. This scale has a small picket every
25 mA, a large picket every 100 mA, and indicates 1000 mA at full deflection.