AMERITRON ALS-500MXCE

To Next Page

ALS-500M Instruction Manual

TABLE OF CONTENTS

ALS-500M Features ........................................................................................................1

General Information.........................................................................................................2

Load Fault Circuit................................................................................................2

Bias Control Circuits ...........................................................................................2

Drive Power.........................................................................................................2

Supply Voltage ....................................................................................................3

SWR Considerations............................................................................................3

Periodic Maintenance ..........................................................................................3

Technical Assistance ...........................................................................................3

Export Modifications...........................................................................................4

Installation .......................................................................................................................4

Location...............................................................................................................4

Power Requirements............................................................................................4

Fuse Holder Installation.......................................................................................5

Auxiliary Battery Installation ..............................................................................5

Grounding........................................................................................................................6

Unibody Vehicles ................................................................................................6

Frame-Type Vehicles...........................................................................................6

Interconnections...............................................................................................................8

Operation .........................................................................................................................9

ALS-500M Parts List.......................................................................................................10

Combiner Board Parts List ..................................................................................10

Power Amplifier Board Parts List .......................................................................11

Output Filter Board..............................................................................................13

Bias Board Parts List ...........................................................................................14

Need help?

Do you have a question about the AMERITRON ALS-500MXCE and is the answer not in the manual?

The ALS-500M is a solid-state linear RF power amplifier designed for amateur radio use, offering a compact and rugged solution for increasing transmission power.

Function Description

The ALS-500M amplifies RF signals from an exciter, providing higher output power for improved communication range and signal strength. It incorporates several protective features to ensure reliable operation and prevent damage from common operating errors.

Important Technical Specifications

Power Output: Produces 400 watts CW (Continuous Wave) with less than 60 watts of drive. Peak envelope output levels on SSB (Single Sideband) can reach up to 600 watts, depending on voice and exciter characteristics.
Frequency Range: Operates on frequencies between 1.5 and 21.6 MHz. A simple modification allows operation above 22 MHz for export models.
Drive Power: Normally requires less than 100 watts of drive for full output. Exceeding 100 watts of drive for long periods may cause component failures. Exceeding 70 watts of peak drive power may cause distortion and increase transmitted signal bandwidth.
Supply Voltage: Requires 11-18 volts positive DC. Rated output power is achieved at 14 volts DC. Output power decreases by approximately 85 watts per volt when the supply voltage is lowered from 14 to 12 volts.
Current Draw: Can reach 80 amperes on voice peaks or 40 amperes of average current. Low current for control and bias circuits is less than 4 amperes.
Dimensions & Weight: Compact size, weighing only 7.5 pounds and measuring 3 3/4"H x 9"W x 15 1/2"D.
Output Network: Features a low-pass output network with multiple sections and a push-pull output configuration, offering excellent harmonic suppression and good overload tolerance.
Transistors: Utilizes four rugged linear RF power devices.
Fuses: Requires two 30-ampere fuses for the heavy red positive high current leads and one 5-ampere fuse for the red low current power lead.

Usage Features

No Tune Operation: Tuning adjustments are not necessary. A single knob selector switch allows operation across its frequency range.
Fast Warm-up Time: As a solid-state amplifier, it has no vacuum tubes, eliminating warm-up time.
Load Fault Protection: Features a load fault trip circuit that bypasses the amplifier if the frequency switch is set incorrectly, or if the reflected power exceeds 70-100 watts. This circuit helps prevent component failures due to operating errors. The amplifier remains "locked out" until the POWER (ON/OFF) switch is cycled off and on.
SWR Considerations: Designed with good overload tolerance, but operation with SWR greater than 2:1 or reflected power exceeding 60 watts should be avoided to prevent heat damage and failure of amplifying devices. Internal safety circuitry disables the amplifier at approximately 70 watts of reflected power.
Bias Control Circuits: Monitors output transistor temperature and adjusts base bias current to prevent overheating.
Thermal Overload Protection: An internal circuit monitors temperature. If the temperature becomes too high, the cooling fan turns on. If it continues to rise, the THERMAL OVERLOAD LED illuminates, and the amplifier ceases operation. This circuit automatically resets when the temperature drops to a safe range.
DC Current Meter: Equipped with a DC current meter to monitor collector current.
Off/On Switch: Allows the amplifier to be bypassed for "bare-foot" operation without disconnecting high current leads.
Remote Off/On Control: A separate connection on the power connector enables low current control of the amplifier's Off/On function for remote mounting.
Relay Control: The RLY jack connects to the transceiver's amplifier relay terminal, providing 12 volts open circuit and drawing less than 100 mA when pulled to ground. Includes a back pulse canceling diode for exciter protection.
Installation: Requires careful consideration of cable lengths and grounding. High current battery leads and ground leads should be kept as short as practical to minimize voltage drop. The maximum voltage drop at maximum power in high current power and ground leads should be limited to 0.2 volts.

Maintenance Features

Low Maintenance: The absence of high voltage eliminates arcing issues caused by dirt and dust.
Cooling System: The primary maintenance involves monitoring and removing dust and dirt to maintain cooling efficiency. Low-pressure compressed air can be used to blow out dust.
Cleaning: A soft-bristled brush and a small amount of alcohol can clean stubborn dust from the fan and other components. Care should be taken to avoid cleaning compounds on relay contacts or switches.
Technical Support: Ameritron provides free technical information bulletins and technical assistance via phone/FAX during business hours for customers servicing their own equipment.
Warranty: Comes with a one-year limited warranty covering defects in material and workmanship (excluding tubes and RF output transistors). Proper maintenance and use are crucial for warranty validity.