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12. Briefly, increase exciter power until the amplifier reaches 1200 watts output,
or
the exciter reaches maximum power without exceeding 1200 watts amplifier
power.
13. After you have verified all of this, the amplifier is ready to operate.
With 100 watts PEP, this amplifier should show approximately 1200 watts of output
power. This can vary slightly from band to band.
ALC Adjustment
Radio manufacturers do not have standardized interfaces. Because of this, ALC
requires some initial adjustment. If the ALC voltage is too low, the ALC will not provide
good control of power levels. If the ALC voltage is too high, the ALC will cause a power
surge and bounce while power slowly settles at the desired steady threshold. This
overshoot, dip, and recovery is caused by slow radio ALC response time, which is
aggravated by excessive ALC loop gain.
ALC attack bounce shows on a steady carrier (such as RTTY, CW, or FM) as a high
initial peak power reading followed by a deep null. The deep null is followed by a slow
settling to the desired power level. On SSB, it will show as a slow warble or modulation
of power levels, especially at the very start of voice transmissions.
If you observe ALC attack bounce, the ALS-1406 will require ALC gain adjustment. The
ALS-1406 has a small blade screwdriver adjustment for setting ALC gain. This
adjustment on the left cabinet side behind the front panel, near the panel meters.
High Duty Cycle Modes
When operating the amplifier with high duty cycle modes such as FM, RTTY, FT8, or
other digital modes reduce the power input so the output is less than 1200W and the PA
current is less than 20A on each module. In addition, if the thermal cutout trips very
often or the power supply fuses blow for no apparent reason (no component failures)
reduce the power to eliminate nuisance fuse blowing or temperature cutouts.
Summary of Contents for ALS-1406/S
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