Instruction Manual

General Information

Amplifier Overview

The Ameritron ALS-1406 is a solid-state, 1200-watt nominal RF output power, 1.8 to 54

MHz amplifier. The ALS-1406 meets or exceeds all FCC requirements governing

amateur radio external power amplifiers.

The ALS-1406 uses two exceptionally low distortion MRFE6VP5600HR6 dual LDMOS

SSB RF power transistors in push-pull. The characteristics of linear high-voltage FETs

are very much like those of triode vacuum tubes. While this amplifier will run more than

1200 watts PEP output, linearity might suffer. Ameritron recommends running 1200

watts or less peak power for maximum linearity. If these instructions are followed, this

amplifier will have comparable IM performance to the best vacuum tube linear

amplifiers.

There are multiple temperature sensors on each PA (power amplifier) module are to

monitor heat to adjust bias and fan speed. The ALS-1406 will disable the amplifier

before the transistors exceed the safe operating temperature limits.

Harmonic suppression comes from push-pull operation of linear devices, followed by

high-quality 5-pole low-pass filters. Many amplifiers use inexpensive ceramic disc or

mica capacitors. Lead inductance of mica or disc capacitors reduces high-order

harmonic suppression. This amplifier uses quality multi-layer high voltage chip

capacitors.

This amplifier greatly exceeds FCC harmonic requirements. HF harmonic suppression

typically 10 to 15 times better than FCC mandated suppression levels. Harmonics are

practically immeasurable on all television channels. An external low-pass filter has

minimal effect with this amplifier.

Antenna switching is through a pair of sequenced miniature relays on a plug-in module.

This facilitates relay servicing or maintenance. Relay switching time is approximately

five to ten milliseconds. The T/R “Relay” control jack is well within the range of almost

any transceiver or radio. The “Relay” jack has an open circuit voltage of 14 volts, and

closed circuit current less than 20 mA. Virtually any modern amateur radio will directly

key this amplifier.

This amplifier includes full metering using large easy-to-read conventional panel meters.

The meters read all critical parameters including forward and reflected peak envelope

RF power.