Command Technologies COMMANDER VHF-2000 Manual page 16

AUTOMATIC DRIVE LIMITING CONTROL
An adjustable automatic level control (ALC) circuit limits the peak output
power. When properly set, this circuit insures that the amplifier can not be
over driven. Rear panel access allows for easy manual adjustment . A
sample of the RF input derives the ALC voltage. Additionally this amplifier
has an RF negative feedback resistance in the cathode circuit to help
cancel excessive RF drive without reducing the amplifier's gain.
Your transceiver's internal ALC will maintain linearity. The amplifier's ALC
will prevent over driving the amplifier. The VHF-1200/2000 ALC circuit
was designed for negative going ALC voltage. Proper adjustment is as
follows:
1. Use an insulated tool when making these adjustments.
2. Tune the amplifier for operation on the desired frequency for full
1500 watts output. (1200 watts on the VHF-1200)
3. With your transceiver set for SSB operation, set the transceiver's
microphone gain for normal operation as specified in its owners manual.
4. While speaking louder than normal into the microphone, adjust the
ALC control on the rear panel thru the access hole. Adjust for 1500 watts
(1200 on VHF-1200) maximum output as indicated on an external peak
reading wattmeter. If an average reading wattmeter is used, adjust for
approximately 600 watts output on voice peaks. (400 on VHF-1200)
A.L.C. ADJUSTMENTS