Ameritron 2WUALS1306 Users Manual
Ameritron ALS-1306
1200-Watt 160-6 Meter
T-MOSFET AMPLIFIER
The Ameritron ALS-1306 is 1200-watt PEP nominal output, 160- through 6-meter amateur radio band (1.8-54
MHz) solid-state amplifier. The compact 10” wide by 6-1/2” high amplifier package, with a depth of only 18”,
fits nearly any station configuration. The attractive desktop amplifier unit weighs only 24 pounds. The ALS1306 meets or exceeds all FCC requirements governing amateur radio external power amplifiers.
Fan speed is regulated by temperature sensors, assuring conservative cooling with minimal noise. Protection
circuitry reduces power as transistors approach conservative thermal limits, and disables the amplifier before
the transistors exceed safe operating temperature limits.
The ALS-1306 uses eight 50-volt, conservatively rated, linear RF MOSFETS. These MOSFET’s are primarily
designed for linear power amplifier applications, not class-C or pulse service. They provide exceptionally low
SSB distortion when compared to most other solid-state devices. Nominal driving power is 100-watts for 1200watts output (approximately 11 dB gain) on most bands.
T/R (transmit-receive) switching is through a pair of sequenced miniature relays on a plug-in module. The plug
in module facilitates relay servicing or maintenance. T/R switching time is approximately five 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 13-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.
An external 50-volt 50-ampere regulated power supply powers the ALS-1306. The supply is wired for 240
VAC (200-260 VAC, 50-60 Hz, 15 amperes), but can be rewired for 120 VAC operation for lighter duty
operation.
ALS-1306 Exihibit VIII Page 1 / 27
TABLE OF CONTENTS
GENERAL OVERVIEW ........................................................................................................................ 1
TABLE OF CONTENTS ....................................................................................................................... 2
AMPLIFIER FEATURES ...................................................................................................................... 3
INSTALLATION....................................................................................................................................4
Airflow Clearances ............................................................................................................................4
Accessory Equipment and Devices ................................................................................................... 4
Installation, Wiring, and Connections ................................................................................................ 4
Station Ground ..................................................................................................................................5
Grounding..........................................................................................................................................5
Coaxial Line Isolators ........................................................................................................................ 6
AMPLIFIER REAR PANEL .................................................................................................................. 6
POWER SUPPLY ................................................................................................................................. 7
Power Line Requirements ................................................................................................................. 7
Power Supply Features ..................................................................................................................... 8
Power Supply Location......................................................................................................................8
INTERCONNECTION WIRING.............................................................................................................9
AMPLIFIER FRONT PANEL .............................................................................................................. 10
Meters (1 and 2) ..............................................................................................................................10
INITIAL OPERATION ......................................................................................................................... 11
OPERATION.......................................................................................................................................12
MARS OR CAP OPERATION ............................................................................................................ 12
ALS-1306 FUNCTIONAL OVERVIEW ............................................................................................... 13
General Operation...........................................................................................................................13
Power Division.................................................................................................................................13
PAM-606 (power amplifier modules) ............................................................................................... 13
2KWF6 Lowpass Filter Assembly....................................................................................................14
Control Functions and Protection Logic...........................................................................................14
Band Decoding................................................................................................................................15
Temperature.................................................................................................................................... 15
Bias .................................................................................................................................................15
Band................................................................................................................................................15
Protection ........................................................................................................................................15
Harmonics .......................................................................................................................................15
SWR................................................................................................................................................16
CIRCUIT BOARD DESCRIPTIONS ................................................................................................... 16
2KWF6 ............................................................................................................................................16
BS2 .................................................................................................................................................16
CB2 .................................................................................................................................................16
MB1.................................................................................................................................................16
PAM-606 (power amplifier module) Boards..................................................................................... 16
PD8 .................................................................................................................................................16
RJ45................................................................................................................................................17
RLY .................................................................................................................................................17
SWR................................................................................................................................................17
SCHEMATICS AND INTERNAL WIRING .......................................................................................... 18
ALS-1306 Exihibit VIII Page 2 / 27
Amplifier Features
This amplifier provides the following standard features:
160- through 6-meter operation, full-power on six meters
Eight conservative linear-service rated, 50-volt MOSFET transistors
New push-pull stripline PA layout with exceptional VHF performance
Energy-efficient solid-state design greatly reduces heat, receive-mode power line draw <100-watts
Exceptional harmonic suppression
Operational in a few seconds, no long filament warm-up time
Clean layout with easy-to-service construction
Quiet variable-speed forced-air cooling system
Power module current and voltage meters with LED illumination
Accurate PEP Forward and PEP Reflected output power metering
Power module balance metering with PA unbalance protection
Reflected power protection
Thermal overload protection
Bandswitch error protection
Easy to understand front panel LED indicators for rapid fault-error diagnosis
Standard negative-going ALC output with front panel adjustment
ALC metering and ALC LED indicator
Fully-regulated external power supply
Compact size 17.5” deep x 7” high x 10.5” wide
Weight amplifier section 24 pounds
ALS-1306 Exihibit VIII Page 3 / 27
Installation
Please look your amplifier and power supply over carefully. Observe the air inlet and outlet ventilation holes.
Facing the amplifier front panel, the cooling air inlets are on the top left and lower right side, including the right
bottom. The warm air outlet is on the lower left side of the cabinet as viewed from the normal operating
position (front view). While outlet air will not be particularly warm, it is never a good idea to have warm air
blow into heat sensitive equipment, such as transceivers or other power amplifiers. Have the same consideration
for your new amplifier and power supply. Be sure the air inlet temperature isn’t substantially above normal
room temperature. Ideally the air inlet should be kept below 32° C or 90° F, although temperatures up to 41° C
or 106° F are permissible. If ambient temperatures exceed these limits it might become necessary to reduce duty
cycle or power.
Warning: Do not block cooling air inlets and outlets! Never expose the amplifier to water or
mist.
Airflow Clearances
The amplifier must have a clear area to the bottom, both sides, and top for proper airflow, and to the rear for
interconnection wiring. It is especially important to avoid obstructions that block the air inlet on the top left, as
well as both lower sides. Two inches clearance is normally adequate for full ventilation. Keep any papers or
loose objects that might impede airflow away from the air inlets and outlets.
Locate the amplifier and power supply away from sensitive equipment such as microphones, audio processing
equipment, or low level audio or radio frequency amplifiers. Generally, the best location for the power supply is
below the operating desk and away from antenna feed lines. This will keep fan noise and any RF coupling to a
minimum.
The power supply has an air inlet at the rear, and air outlets on the top. The highly efficient power supply
produces very little heat, but the inlet and outlet must remain open to normal room temperature air.
Accessory Equipment and Devices
One of the most common causes of amplifier failures or erratic fault protection alarms is installation of antenna
switches, lightning protection devices, or baluns with lightning spark gaps in high SWR lines. If your antenna
system has an SWR high enough to require an antenna tuner, do not use 50-ohm lightning protection devices
after the tuner.
Installation, Wiring, and Connections
The power supply is factory wired for 200-260 Vac. It uses a standard NEMA-6-15P 15-ampere 240-volt plug.
The round center pin is the safety ground. Do not remove the safety ground.
CAUTION!
have completed the following four steps:
1. Insert the 15-ampere 250V fuses into the two black fuse caps.
2. Insert the fuse and cap assemblies into the power supply’s fuse holders. The fuses lock in place
3. Connect the power supply to the amplifier.
Before
with a slight turn.
connecting the power supply to an electrical outlet, always be sure you
4. Be sure the amplifier power switch is turned off.
ALS-1306 Exihibit VIII Page 4 / 27
Caution! Fuses have both voltage and current ratings. Use only 250V rated fuses in this
device. The voltage rating generally is marked on fuses. DO NOT use automotive-type low
voltage fuses in any power line application. For 240-volt operation, 15-ampere fast blow
fuses are required.
Warning: Never insert the power supply cord into the outlet until you have completed all
installation steps! The last step, after verifying all connections, is connecting the power
supply to the power mains.
Position the amplifier at or near the desired location on your operating desk so you have access to the rear
panel, and connect the rear panel cables. Do not connect the power mains at this time!
Station Ground
Common rumor is that a station equipment ground reduces RFI (radio frequency interference) or improves
signal levels. Generally, changes in RFI or signal quality with the addition or removal of a station ground
indicate an antenna or feedline installation problem. Typical problems causing desktop RFI issues include the
following:
1. lack of suitable baluns
2. improper feedline routing near antennas, or improperly designed antennas
3. antennas too close to the operating position
4. poor equipment cabinet design, such as non-bonded or grounded equipment covers or panels
5. poorly designed low-level audio line shield entrances, such as shields allowed to enter cabinets instead
of grounding at the enclosure entrance
6. improper antenna feedline building entrance, lacking a properly grounded entrance panel
Rather than patching a system problem at the desk, it is much better to correct defects at the problem source.
Grounding
The amplifier and power supply cabinets ground through a safety ground pin on the power plug. This system
depends on a properly wired power outlet.
Lightning protection grounds do very little good at the operating desk. Lightning protection grounds belong at
the antenna cable entrance to the building. Antenna feedline and control entrance grounds must electrically
bond, with low impedance and resistance, to the powerline entrance ground.
RF grounds and lightning grounds are most effective at the antenna and at the feedline entrance, rather than the
operating desk.
There are ground lugs on the rear of the amplifier and power supply. These ground lugs are provided for use
with a station ground buss on the desk. A station ground buss helps ensure equipment cabinets on the desk are
close to the same electrical potential. These ground lugs are NOT for direct, independent, connections to
external ground rods or ground systems. The ground lugs are for connections to a desktop ground buss system.
A proper desk ground buss is a short, wide, conductor that runs the width of the operating position. All
equipment should bond to that buss, unless a manufacturer specifies otherwise.
ALS-1306 Exihibit VIII Page 5 / 27
Coaxial Line Isolators
The goal of every operating position is to maintain all equipment cabinets and housings at the same RF
potential. Isolators on or near the desk are contrary to this goal, and actually promote or encourage cabinet or
chassis RF potential differences. Never install coaxial line isolators between desktop radio equipment.
Proper line-isolator installation points are either just outside the operating room entrance and/or close to the
problem’s actual source. If the desktop has defective cables or connectors, or poor equipment cabinet design,
locate and correct the actual problem. If an RF problem appears at the operating position, correction, repair, or
replacement of defective equipment is in order.
Amplifier Rear Panel
Amplifier Rear Figure 1
50VDC INPUT To prevent connecting the power plug wrong, the large black multi-pin connector is indexed by the offset in
two round pins. One round index pin is closer to the outer connector edge. Mate the round pins and holes
and seat the male plug fully onto the amplifier rear panel pins.
ALC Optional connection. Connects to radio ALC input. Mandatory if using a radio over 100 watts.
RELAY Connect to radio amplifier keying line. Radio must pull this line below 2 volts to transmit.
GND Connect to station ground buss. This connection is for desktop safety.
RF IN Connect through good 50-ohm coaxial cable of any reasonable length to radio’s antenna output connector.
This can be a smaller cable, such as RG-58/U. Do not use or install an antenna tuner on this port.
RF OUT To 50-ohm antenna, antenna tuner, power meter. This is the high power output. 50-ohm coaxial cable and
system beyond must safely handle at least 1200-watts.
ALS-1306 Exihibit VIII Page 6 / 27
1.) If you use a desktop grounding buss system, connect the station ground buss to the rear panel wing nuts.
National safety codes require the station ground electrically bond to the power mains safety ground at
the building entrance. Do not connect the amplifier to its own isolated ground rod or ground system.
2.) Connect the power supply to the amplifier.
3.) Connect the RELAY line to the transceiver’s amplifier relay, amp, or tx port. This port is defined in
radio manuals in amplifier interfacing sections. This port must pull low for transmit, and be open circuit
when receiving. Relay control voltage from the ALS-1306 is 12 volts positive with only 15 mA current.
You should always check your transceiver’s manual, but almost any standard transceiver directly
interfaces with this amplifier.
4.) Connect the RF OUT (output) port to the appropriate point in your station. This is the high power RF
output cable. This connection would go to your 1500-watt rated Power/SWR meter, antenna, or antenna
matching device. Good quality Mini-8 or RG-8X cables are acceptable for anything but RTTY use,
although larger RG-8 style cables are normally preferred. Your antenna matching system, or antenna
tuner, must connect to this port.
5.) Connect the IN connector to your transceiver. Do not install any active antenna matching devices on this
port. In general the shortest and most direct cable connection is best, although high quality cables can be
very long without adverse effect on performance. RG-58/U or Mini-8 (RG-8X) style cables are
acceptable. You should never use a tuner of any type on the amplifier input, nor should you drive this
amplifier with over 100 watts peak envelope power. Never use a non-amateur radio device with this
amplifier.
6.) The ALC line is optional. In general, the internal ALC in the transceiver is adequate for power control.
With transceiver power>100W, ALC should be used. The ALC monitors the RF output power and
reflected power supplied by the ALS-1306 to the load.
7.) Operate the bandswitch manually during initial testing. Do not connect band decoders, band data lines,
or computer interfaces until initial tests are completed and the amplifier is functioning normally.
Power Supply
The external power supply for the ALS-1306 is a voltage-regulated current-limited switching supply. It contains
14-volt positive and negative supplies, as well as dual 50-volt 25-ampere continuous (30-ampere peak) fully
current-limited supplies. Each PAM (power amplifier module) in the ALS-1306 operates from independent 50volt modules, giving a total dc supply rating of 2500 watts average power and 3000 watts peak power to the
power amplifier modules.
Power supply to amplifier interconnections are through a heavy-duty cable using a large Cinch Jones connector.
Power Line Requirements
This amplifier ships wired for a nominal mains voltage of 230 Vac. Maximum average powerline current at full
power output is 12 amperes at 240 volts. Two 250-volt 15-ampere fuses fuse the power line. The switching
power supply automatically adapts to any mains voltage between 200 Vac and 260 Vac, and does not require
adjustments or tap changes within that range.
ALS-1306 Exihibit VIII Page 7 / 27
Note: 120-volt power mains operation is possible with a reduction in CW or RTTY power.
Because average power is very low, SSB operation is unaffected by 120-volt operation. 120V fuse size is 25-amperes maximum.
Power Supply Features
Efficient operation from 200-260 volts ac (12 amperes typical at full output power)
Low standby and receive power drain, typically less than 100-watts with ALS-1306 attached and
operational
Generator and inverter friendly with acceptable powerline frequency range 40 to 400 Hz
Fully-regulated current-limited outputs
Step-start to limit stress on power supply components
Exceptional filtering and RFI suppression eliminates receiver birdies common to most SMPS
Compact light-weight design
Power Supply Location
Locate the power supply in a convenient ventilated area near the amplifier location. Avoid placing the power
supply next to sensitive equipment, such as audio processors, transceivers, or microphones. For safety, ground
the wing nut stud on the supply rear to the station ground buss. The station ground buss should comply with
National Electrical Codes. NEC and fire protection codes mandate direct bonding of station ground rods or
systems to the power line entrance ground system. If station ground rods are not bonded to the utility entrance
ground, likelihood of equipment or property damage and personal risk increases.
ALS-1306 Exihibit VIII Page 8 / 27
Interconnection Wiring
Interconnections Figure 2
ALS-1306 Exihibit VIII Page 9 / 27
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