AMERITRON ALS-1306 - ALC Adjustment

Revision 2
20
the REF position. If you see reflected power deflection, check your RF cables.
Reminder: You cannot use a tuner in your radio, or between your radio and this
amplifier, to match the antenna system. Any antenna matching must be between the
amplifier and the antenna, and the antenna tuner and beyond the amplifier must be
conservatively able to handle over 1200 watts of carrier or peak envelope power.
10. Place the amplifier in OPERATE position (fig.2 ref 8). Be sure the BAND on the
amplifier matches the band selected on the transceiver.
11. Place the transmitter or transceiver into transmit in FM, AM, RTTY, or CW modes. The
green TX LED (fig.2 ref 6) should light. The forward power (fig.2 ref 2) should increase
to approximately ten times the initial exciter power reading. Reflected power should
remain very low, and the PA current should increase slightly on both scales of the current
meter (fig.2 ref 1). No other LED’s should illuminate.
12. Briefly, increase exciter power until the amplifier reaches 1200-watts output, or increase
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-1306 will require ALC gain adjustment. The ALS-
1306 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.