OPERATION
Duty-Cycle Considerations
The ALS-600PS linear power supply is equipped with a front panel switch labeled
Normal/RTTY. This switch is used in the normal position for SSB and CW operation.
The RTTY position is used for continuous carrier modes. This position limits the voltage
to about 42VDC no load, thereby limiting the output power to 350 watts. In the RTTY
position, the amplifier can be operated for 10 minutes key down with a 50% duty cycle.
The ALS-600SPS switching power supply does not have this Normal/RTTY switch.
Note: Ensure that you limit your ALS-600 output power to 350 watts maximum for RTTY
or other continuous carrier modes.
ALC Set-Up
The Amplifier's back panel has an ALC limit control that limits the amount of ALC
voltage sent to the transceiver. This is necessary because there is not a standard
transceiver ALC voltage. To set the ALC limit control, adjust the ALC set knob on front
of the amplifier to 10 (fully clockwise), and the ALC limit control on the back of the
amplifier fully counter-clockwise as viewed from the rear (or just disconnect the ALC
cable). Key your transceiver and apply enough drive into the amplifier until the
amplifier's power meter reads about 500 watts. This will result in approximately 600
watts PEP output power.
Note: The amplifier's power meter should never exceed 700 watts, and the drive level
must not exceed 100 watts.
Plug the ALC cable into the back of the amplifier (if not already done). Turn the ALC
set knob (on front of amplifier) to 0 (fully counter-clockwise). Key amplifier with RF
applied. Adjust the ALC limit control (on back of amplifier) until the ALC light on the
front of the amplifier just comes on. No other adjustment needs to be done to the ALC
limit control unless a different transceiver is used. All ALC adjustments can now be
made with the ALC Set control on the front of the amplifier.
The following sections describe how to adjust the exciter and ALC control for proper
operation. If ALC is not used, the exciter output controls must be used to limit the power
to the levels described in the text that follows (drive power must never exceed 100 watts).
SSB Operation
SSB voice operation normally does not have transmit time limits. Reflected power levels
should be kept below 50 watts peak on SSB.
To set the proper SSB operating level, first set the ALC SET control fully clockwise.
While using normal modulation, increase your transceiver’s output power (not to exceed
21
To Next Page