AMERITRON AL-572, Инструкция по эксплуатации

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Ameritron AL-572 Instruction Manual
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should be adjusted until the ALC voltage meter slightly flickers (ALC position of the
"MULTIMETER" switch) while operating with normal output power levels.
The ALC circuit will limit the amplifier's grid current to a safe value if anything accidentally
changes in the station or the antenna. The CW keying waveform of the radio will remain
unaltered when the ALC is adjusted in this manner.
Note: Caution should be exercised if the ALC SET is used to control the CW power output
with the exciter power control set at maximum. Key clicks may be produced if the
exciter has a poor ALC response time. Check for proper wave shape when using the
ALC in the amplifier exclusively to control the RF output power.
Rear-panel "ALC LIMIT" control
The "ALC Limit" control (rear panel) limits the maximum voltage available from the ALC
circuit. This control is necessary only because the ALC response times and voltage requirements
for exciters have never been standardized. The ALC voltage requirements may even vary
between different models produced by the same manufacturer.
If the ALC response time of the exciter (transceiver) is faster than the rise time of the RF
envelope, there will be no voltage compatibility problems. The ALC voltage from this amplifier
will automatically self-adjust to the value required by the exciter.
If the ALC voltage requirements are low and/or if the ALC attack time is slow, the ALC may
cause the output power to "pump" at a very slow rate. The undesired "pumping" can be corrected
by reducing the amplifier's ALC output voltage with the "ALC Limit" control (R1).
A full counter-clockwise "ALC Limit" setting will produce approximately 10 volts of maximum
negative ALC voltage. A full clockwise setting (viewed from amplifier rear) will produce no
ALC voltage. Always start with this control fully counter-clockwise before slowly advancing
this control clockwise. The "
ALC Limit Adjustment " section that follows gives adjustment
details.
ALC Limit Adjustment (rear panel)
This adjustment procedure should be used if "pumping" occurs from excessive transceiver ALC
sensitivity and/or slow transceiver ALC response time:
1. Load the amplifier for maximum output on any band (see tuning instructions later in this
manual).
2. Adjust the "ALC SET" control on the front panel and the rear panel "ALC Limit"
potentiometer to their full counter-clockwise positions.
3. Apply full exciter drive power, and adjust the rear panel "ALC Limit" potentiometer
clockwise (rear view) until the amplifier's ALC output voltage meter (multimeter "ALC"
position) indicates 6 to 10 volts. As an alternative, the potentiometer can be adjusted
clockwise until the RF output power reaches 300-500 watts.
4. Adjust the front panel ALC SET control to the desired power level.