AMERITRON ALS-706 User manual

AMERITRON ALS-706/S
600 WATT 160-6 Meter NO TUNE
LDMOS-FET AMPLIFIER
INSTRUCTION MANUAL
WARNING!
NEVER APPLY POWER TO THIS AMPLIFIER WITH THE COVER REMOVED!
CONTACT WITH THE POWER SUPPLY VOLTAGES IN THIS AMPLIFIER CAN BE FATAL!
PLEASE READ THIS MANUAL BEFORE OPERATING THIS EQUIPMENT!
Factory
116 Willow Road
Starkville, MS 39759 USA
662-323-8211
Version 0
Printed in the USA

Contents
Amplifier Features ......................................................................................................................................... 4
Quick Start .................................................................................................................................................... 5
Installation and Operation......................................................................................................................... 5
Placement............................................................................................................................................. 5
Power Line or Mains Connections ............................................................................................................ 5
Power Mains......................................................................................................................................... 5
adio and Antenna Connections .............................................................................................................. 6
Alerts .................................................................................................................................................... 7
Operation .................................................................................................................................................. 8
Introduction ................................................................................................................................................... 9
General Operation....................................................................................................................................... 10
Power Supply and Power equirements................................................................................................ 10
ALS-600PS Power Supply Features .................................................................................................. 10
ALS-600SPS Power Supply Features................................................................................................ 10
Power Line equirements .................................................................................................................. 11
Power Supply Location....................................................................................................................... 11
Amplifier Overview .................................................................................................................................. 11
Installation ................................................................................................................................................... 12
Installation Clearances ........................................................................................................................... 12
Installation Warnings .............................................................................................................................. 12
Accessory Equipment and Devices.................................................................................................... 12
Installation, Wiring, and Connections ................................................................................................. 13
Safety and Lightning Grounding......................................................................................................... 13
Station F Ground ............................................................................................................................. 14
Coaxial Line Isolators ......................................................................................................................... 14
Front Panel Controls ................................................................................................................................... 15
Back Panel Connections......................................................................................................................... 16
Interconnections.......................................................................................................................................... 17
Optional adio Interface Cables ........................................................................................................ 18
Operating Frequency ange .................................................................................................................. 19
MA S or CAP Operation.................................................................................................................... 19
Warning Lights ........................................................................................................................................ 20
Initial Operation ........................................................................................................................................... 21
ALC Adjustment...................................................................................................................................... 22
High Duty Cycle Modes .......................................................................................................................... 22
F Exposure Information ............................................................................................................................ 23
ALS-600PS Voltage Settings ............................................................................................................. 25
ALS-600SPS Switching Power Supply ................................................................................................... 26
ALS-600SPS Voltage Settings ........................................................................................................... 26
ALS-706 Limited Warranty .......................................................................................................................... 28
Tables
Table 1 Quick Start Fault Alarms .................................................................................................................. 7
Table 2 Optional adio Interface Cables .................................................................................................... 19
Table 3 Band Frequency anges ............................................................................................................... 19
Table 4 LED Alarm Indicators ..................................................................................................................... 20
Table 5 F Exposure Distance Chart in Meters ......................................................................................... 23
Table 6 Approximate Antenna Gain for Some Common Antennas ............................................................ 24
Table 7 ALS-600PS Voltage Settings ......................................................................................................... 25
Table 8 ALS-600SPS Jumper Settings....................................................................................................... 26

Fig res
Figure 1 Basic Interconnection ..................................................................................................................... 7
Figure 2 Front Panel ................................................................................................................................... 15
Figure 3 ALS-706 Back Panel..................................................................................................................... 16
Figure 4 ALS-600PS Jumper Pins .............................................................................................................. 25
Figure 6 ALS-600SPS Board Diagram ....................................................................................................... 26
Manual Version 0 03-22-2021

4
Amplifier Features
This amplifier provides the following standard features:
ɀ 160 through 6-meter operation, full-power on six meters.
ɀ One conservative linear-service rated 50 volt ual L MOS FET transistor.
ɀ New push-pull stripline PA layout with exceptional VHF performance.
ɀ Energy-efficient solid-state design greatly reduces heat, <100 watts power line
draw on receive.
ɀ Exceptional harmonic suppression.
ɀ Operational in a few seconds, no long filament warm-up time.
ɀ Clean layout with easy-to-service modular construction.
ɀ Quiet variable-speed forced-air cooling system.
ɀ Power module current and voltage meters with LE illumination.
ɀ Accurate PEP Forward and PEP Reflected output power metering.
ɀ Reflected power protection.
ɀ Thermal overload protection.
ɀ Bandswitch error protection.
ɀ Easy to understand front panel LE indicators for rapid fault-error diagnosis.
ɀ Standard negative-going ALC output with front panel adjustment.
ɀ ALC metering and ALC LE indicator.
ɀ Fully-regulated external switch mode power supply, or linear unregulated supply.
ɀ Compact size 14” deep x 7” high x 9.5” wide.
ɀ Weight amplifier section 15 pounds.
Please read the entire manual completely and understand the
operations before trying to operate this amplifier.

5
uick Start
Thank you for purchasing this amplifier system. The ALS-706 is a 600 watt nominal PEP
output amplifier and power supply system. This amplifier covers 160 to 6 meters.
Nominal drive power is 100 watts or less. This system will not and does not operate on
the CB band.
The ALS-706 interfaces with most modern amateur radio transceivers, including band
data information. Band data connection will require purchasing an Ameritron interface
cable for your radio.
Carefully unpack this amplifier and power supply. Cabinets and controls can be broken,
bent, or dented with rough handling. Please inspect everything for physical shipping
damage; this includes cabinets and chassis. Ameritron does not package dented or
damaged units. If your unit is damaged or dented, including broken knobs or switches, it
is always from handling somewhere between Ameritron and the end user. In the event
of cabinet damage or broken controls, please retain all packing materials and containers
so damage claims can be resolved.
Installation and Operation
Placement
WARNING: o not block ventilation holes. o not expose to moisture,
water, or external heat.
This unit is two components, a power supply and an amplifier section. The power
supply, within limits of cable length, may be placed out of the way. The amplifier section
should be in a convenient location within arm’s reach of the operating position. o not
extend the amplifier power supply dc power cable.
Power Line or Mains Connections
Power Mains
1.) The system uses one of two power supplies available. The ALS-600SPS
switching power supply that can run on 95-130 VAC 50-400 Hz 15A and is well
regulated or the ALS-600PS unregulated choke input supply that can run on 100-
130 VAC 50-60 Hz 15A.
2.) The plug is a NEMA 5-15P, 120 VAC at 15 amperes. This is a standard USA
120V plug with a safety ground pin. o not remove the ground pin.
3.) o not operate with line voltage below 95 or above 135 volts when wired for 120
volts, or below 185 or above 260 volts when wired for 240 volts.
4.) Larger power wiring will not help performance or power unless amplifier high
voltage is unstable.
5.) The ALS-706 when using the ALS-600SPS exceeding the safe power supply
current on the supply line will force the overloaded supply into shutdown.
Shutdown is reset by turning the main power switch off for a brief time. If the

6
power supply has a permanent overload or the supply has failed, it will not reset.
The ALS-600PS uses only the protective fuses.
6.) The ALS-600PS has an RTTY and Normal voltage switch. The RTTY position
allows higher amplifier efficiency at reduced power.
See the power supply details included with the particular power supply for details
specific to each supply.
Radio and Antenna Connections
WARNING: Forcing connector engagement can result in permanent connector
damage. Solder on the outside of center pins or bent pins are primary causes of
female connector damage. External solder or bent center pins can permanently
damage the female.
1.) RF connections are through standard UHF female connectors. Use good cables
with quality UHF male (PL259) connectors. The output cable must safely handle
at least 600 watts.
2.) Look at the connectors. The amplifier‘s female connectors have notches on the
outer thread edge. The cable males should have protruding tabs on the inner
shell beyond the center pin insulator. These tabs and notches prevent unwanted
connector rotation. The male’s tab or tabs must be aligned with the female’s
notches. This interlocking prevents connector rotation.
3.) With a firm handgrip, gradually tighten RF connectors while making sure the male
tab interlocks with the amplifier’s female connector notch. o not use excessive
force on connectors. Check for proper tightness and seating by wiggling and
flexing the cables near the connector and watching for any indications of
abnormal male connector movement, and by wiggling the cable while hand
tightening the male shell. If done properly, the connector will be solidly locked
without need for pliers or other tools
4.) ALC and Relay (keying) connectors are phono females. The phono males from
external cables should push directly in with a snug fit.
5.) The Relay line has low voltage (<14V) low current (<20 mA). Transmit is enabled
by pulling the Relay line to ground with a relay contact or transistor. Read your
radio manual. Unless you have a very unusual radio, your radio will directly key
the amplifier.
6.) The remote and radio band data connectors are specialized connections. They
are for use with Ameritron supplied cables only.

7
Alerts
This amplifier has front panel alert codes using the SWR, PA, TX, warning LE ’s and
bandswitch band indicators. When a fault code appears, the amplifier is disabled. When
an operating problem is corrected, operation is restored and alerts canceled by moving
the front panel Standby/Operate switch to Standby.
The following table applies to faults:
Warning Light
Steady
Warning Light
Flash Fault Cause or Cure
SW TX Antenna eflected Power High antenna SW or intermittent
antenna or feed line connection
SW , PA Band Wrong filter
Filter input SW
Exciter or amplifier on incompatible
band, filter failure
PA, TX PA FET too hot Excessive power for duty cycle or
SW , lack of proper airflow
10M, PA, TX Illegal 11 meter operation Excessive 27 MHz signal level
EM, PA No data or bad band data
when on remote
Defective or improper remote cable, or
bad radio band data information
Table 1 Quick Start Fault Alarms
Figure 1 Basic Interconnection

8
Operation
Before attempting operation:
1. This amplifier is optimized for 50-ohm loads. Be sure your antenna system SWR
is as low as possible. As SWR increases from 1:1, either heat or distortion will
increase.
2. Be sure your antenna system, including any switches, baluns, matching circuits,
or lighting protection devices, are in good condition and will safely handle high
power.
3. Connectors, cables, and antennas must not have loose connections or
insulation failure issues.
4. Your exciter must be adjustable to significantly less than 100 watts output. Start
at 50 watts maximum drive power and increase or decrease drive to reach
desired power. o not exceed 25 amperes or 600 watts output, and do not drive
into non-linearity on SSB. A trapezoid scope pattern is recommended for drive
adjustment. Overdriving results in an excessively wide signal, and overdriving
can damage the amplifier.
5. Power mains should be reasonably stable and match power supply voltage
wiring.
6. The low pass filters cut off just above the traditional primary amateur bands. A
primary band’s filter is used on the next lower WARC band. For example, the
20-meter low pass filter is used on 30 meters. Some radios do not supply
enough band data to know the exact band. With these radios, amplifier band
data displays the next higher primary band above the radio’s WARC band. If
you are using such a radio, do not be alarmed if 15 meters illuminates when the
radio is on 17 meters. This is still the correct filter.
7. The amplifier will shut off with an incorrect band selection, high antenna SWR
(even for an instant), if safe thermal limits are reached, or with catastrophic
failures.
8. The ALS-706 reads peak envelope power on forward and reflected RF power
scales.
With proper installation, basic operation is straightforward:
1.) Set the bandswitch to the desired band. This happens automatically in the REM
position with a suitable radio interface cable.
2.) Set the exciter or transceiver to the desired power below 100 watts.
3.) Place the Standby switch in the Operate position.
4.) Transmit, and watching Forward Power metering, be sure power does not
exceed 600 watts on peaks.
5.) For high duty cycle modes and long transmissions, reduce the power. The
amplifier will shut down if the FETs reach the maximum safe temperature limits.

9
Introduction
Thank you for purchasing this amplifier system.
The ALS-706 is a compact 600 watt nominal PEP output amplifier. It uses an external
power supply system. This amplifier covers 160 to 6 meters. Nominal drive power is 100
watts or less. NOTE: This amplifier excl des all operation between 26 and 28 MHz.
Ca tion: This amplifier has an FCC mandated automatic disconnect and other features
preventing 27-MHz operation. There is no available circ itry or control provision to
circ mvent this locko t.
The ALS-706 interfaces with most modern amateur radio transceivers. Supported band
data input includes ICOM compatible analog voltage, Elecraft and Yaesu BC band
data, and Kenwood serial data. With proper interface cables and data, this amplifier will
automatically change bands in step with transceiver band changes. Automatic band
selection using a band data port or band decoded bus requires purchasing an Ameritron
interface cable for your radio.
Carefully unpack this amplifier and power supply. Please inspect everything for physical
shipping damage; this includes cabinets and chassis. Ameritron does not package
dented or damaged units. Cabinets and controls can be broken, bent, or dented with
rough handling. If a new unit arrives mechanically damaged, including broken knobs or
switches, it is always from handling somewhere between Ameritron and the end user. In
the event of cabinet damage or broken controls, please contact the dealer immediately.
To permit claim processing, retain all boxes and packing materials.
The Ameritron ALS-706 is 600-watt nominal output, 160 through 6 meter amateur radio
band, solid-state amplifier. The ALS-706 uses one MRFE6VP5600HR6 dual L MOS
field effect transistor. The L MOS FET is specifically designed for broadcast power
amplifier applications and is specified to handle up to 65:1 SWR under full power. Fan
speed is regulated by temperature sensors; assuring conservative cooling with minimal
noise.
Nominal driving power is 80-100 watts for 600 watts output (approximately 9-10 dB
gain) on most bands. The compact 9-1/2” wide by 7” high amplifier package (depth only
14”) fits nearly any station configuration. This attractive desktop amplifier unit weighs
approximately 15 pounds.
An external 50-volt 25-ampere CCS power supply powers the ALS-706. Two different
supplies are available. The ALS-600SPS switching regulated supply and the ALS-
600PS unregulated supply. These supplies operate on all standard residential power
line voltages.
Please read the manual completely and understand the operations
before trying to operate this amplifier.

10
General Operation
Power Supply and Power Requirements
ALS-600PS Power Supply Features
ɀ Normal operating range is from 100 volts up to 130 volts 50/60Hz (12 amperes
typical full carrier power) or between 200 and 250 volts, 50/60Hz (6 amperes
typical at full carrier power).
ɀ A unique “buck-boost” winding allows compensation for up to six different power
line voltages centered on 115 and 230 volts. This versatile Ameritron feature
maintains optimum voltages on the amplifier components for maximum
performance and life
ɀ The ALS-600PS standard power supply uses an input choke to provide low
power factor loading on power lines. This reduces the peak currents drawn from
the line and improves the voltage regulation of the supply. This makes the ALS-
600PS generator and inverter friendly within the acceptable power line frequency
range of 50 to 60 Hz
ɀ Step-start to limit stress on power supply components
ɀ An illuminated cross-needle meter monitors the 50V line output voltage and
current
ɀ Weight 33 lbs.
ALS-600SPS Power Supply Features
ɀ Efficient operation from 100-130 volts ac (12 amperes typical at full output power)
ɀ Low standby and receive power drain, typically less than 100 watts
ɀ Generator and inverter friendly with acceptable power line frequency range 40 to
400 Hz
ɀ Inrush protection
ɀ Fully-regulated current-limited outputs
ɀ Excellent voltage regulation
ɀ Exceptional filtering and RFI suppression eliminates receiver birdies common to
most SMPS
ɀ Light weight 13 lbs.
ɀ An illuminated cross-needle meter monitors 50V line output voltage and current.
The ALS-706 external power supplies contain 14 volt positive and negative supplies, as
well as a 50-volt 25-ampere continuous (30-ampere peak) main supplies. The ALS-706
PA (power amplifier) module operates from 50 volts, giving a total dc supply rating of
1250 watts average power and 1500 watts peak dc power. The 14 volt supplies are for
illumination, bias, and control functions.
Power supply to amplifier interconnections are through a heavy-duty cable using reliable
Cinch Jones connectors.

11
Power Line Requirements
This amplifier ships wired for a nominal mains voltage of 120 VAC with either supply.
Maximum power line current at full power output is 12 amperes at 120 volts. 250-volt
rated 15-ampere fuses protect the power line. Always use 125V or 250V line fuses.
The linear supply requires changing taps for different line voltages. The switching power
supply is voltage regulated, current limited, and automatically adapts to any mains
voltage between ~95 VAC and 135 VAC. The ALS-600SPS switching supply does not
require adjustments or voltage tap changes for 125VAC use.
Note: 240 volt power mains operation is possible. This will not normally increase power.
Because average power is very low, SSB operation is generally unaffected by 120 or
240 volt operation. 240V fuse size is 8 amperes maximum, fast blow only. The fuse
must have a voltage rating of 250VAC
Power Supply Location
Locate the power supply in a ventilated area convenient to 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 bus. The station ground bus should comply with National Electrical
Codes. NEC safety and fire protection codes mandate direct bonding of station grounds
to the home power line entrance ground. Station ground rods not directly bonded with a
low impedance connection to utility entrance grounds will increase equipment or
property damage, and increase personal risk, significantly.
Amplifier Overview
The Ameritron ALS-706 is a solid-state, 600 watt nominal RF output power, 1.8 to 54
MHz amplifier. The ALS-706 meets or exceeds all FCC requirements governing
amateur radio external power amplifiers.
The ALS-706 uses one low-distortion MRFE6VP5600HR6 dual L MOS RF power
transistors in push-pull configuration. Ameritron recommends running 600 watts or less
peak power for maximum linearity and component life. It is always a good idea to use an
oscilloscope to verify proper linear SSB operation.
Protection circuitry reduces the power as the transistor approaches conservative
thermal limits, and disables the amplifier before exceeding safe transistor operating
temperature limits. (See warning table.) A fan speed-control system monitors heatsink
temperature.
Room temperature amplifier bias is nominally 2A. Amplifier supply voltage is nominally
50 V C. Maximum allowable voltage is 58 volts.
Harmonic suppression comes from push-pull operation of linear devices, followed by 5-
pole low-pass filters. This amplifier uses modern multi-layer high voltage chip capacitors
where applicable. Chip capacitors, due to low internal inductance and higher Q, offer
significantly improved harmonic suppression. Harmonic and spurious suppression is
excellent; external low-pass filters have minimal effect on TVI. The most likely cause of
any RFI or TVI will be fundamental overload from inadequate consumer device RFI
immunity.
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 approximately 14 volts, and closed
circuit current less than 15 mA. Virtually any modern amateur radio will directly key this

12
amplifier. Relay switching time is approximately ten milliseconds. Radio adjustable TX
delay should be set to 10 mS.
This amplifier includes full metering using a large easy-to-read conventional cross-
needle panel meter. The meter reads all critical parameters, including Forward and
Reflected peak envelope RF power, voltage and, current.
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 hand side cabinet bottom. Warm air exits
vents at the cabinet rear.
While outlet air will not be particularly hot, 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 air inlet
temperature is not substantially above normal room temperature. Ideally, the air inlet
temperatures should be below 32°C or 90°F, although temperatures up to 41°C or
106°F are permissible. Should ambient temperatures exceed these limits, it might
become necessary to reduce duty cycle or power.
Warning: Do not block cooling air inlets and outlets!
Ne er expose the amplifier to excessi e heat, dirt, water, or mist.
Installation Clearances
The amplifier must have a clear area to the bottom, both sides, and top for proper
airflow, and to the rear for exhaust air and interconnection wiring. It is especially
important to avoid obstructions that block the air inlet on the top left, as well as both
lower sides. One to 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 feedlines. This will minimize unwanted mechanical, acoustical,
and electrical coupling.
The power supply produces very little heat, but the air inlet and outlet must remain open
to normal room temperature air.
Installation Warnings
Accessory Equipment and Devices
Second to operator error, the most common amplifier failure or erratic fault protection
shutdown is from antenna switches, lightning protection devices, or baluns with lightning
spark gaps in high SWR coaxial lines. o not use 50-ohm lightning protection devices
on lines with high SWR, such as between and antenna and antenna tuner. High SWR
can raise the RF voltage to above the voltage limits of the protection device so that it
arcs over. Be sure any lighting protection devices are in good working order and is rated
above the power level of the amplifier.

13
Installation Wiring and Connections
The ALS-600SPS switching power supply is factory wired for 100-130 VAC. The linear
ALS-600PS is prewired for 120-125 VAC nominal voltage. Both use standard NEMA-5-
15P 15 ampere 120-volt plugs. The round center pin is the safety ground. o not
remove the safety ground.
CAUTION! Before connecting the power supply to an electrical outlet, always be sure
you have completed the following four steps:
1. Insert the 15 ampere 250V f ses into the two black f se caps.
2. Insert the f se and cap assemblies into the power s pply’s f se holders.
The f ses lock in place with a p sh and slight t rn.
3. Connect the power s pply to the amplifier.
4. Be s re the amplifier power switch is off.
Caution! Fuses ha e both oltage and current ratings. Use only 250V rated
fuses in this de ice. The oltage rating is generally marked on fuses. DO NOT use
automoti e-type low oltage fuses in any power line application. See power
supply instructions.
Warning: Ne er insert the power supply cord into the outlet until you ha e
completed steps 1 through 4 abo e!
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!
Safety and Lightning Grounding
The power supply cabinet grounds 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. Station ground
rods must always electrically connect through low impedance and resistance
conductors to the power line entrance ground. The national electrical code in the USA
prohibits isolated ground systems at dwelling entrances. Isolated ground rods or
systems connected to conductors entering a dwelling increase the damage likelihood
during storms, and increases fire hazard and shock risk.
RF grounds generally belong at the antenna or at the feed line entrance. With the
special exception of a small floating counterpoise grounds, RF grounds at or very near
the dwelling should bond into the mains ground outside the dwelling. This is especially
true with earth contact grounds.
There is a ground lug on the amplifier rear panel. This ground lug provides a convenient
chassis connection for operating positions with ground bus on the desk. A station
ground bus helps ensure desk area equipment cabinets are close to the same electrical
potential for radio frequencies and lower. Equipment ground lugs are NOT for
independent wires or connections to external ground rods or ground systems from each

14
piece of equipment. They are for connection to a desktop ground bus system common
to all equipment, if you prefer to use such a system.
Independent ground wire connections are counterproductive. Never use RF isolators
between the amplifier and radio. Never use long independent wires to external grounds.
Never connect desk equipment to ground rods that do not bond into the mains entrance
ground rod.
Station RF Ground
Common rumor is a station equipment ground reduces RFI (radio frequency
interference), reduces lightning damage, or improves signal levels. Generally, changes
in RFI or signal quality, with the addition or removal of a station ground, indicate an
antenna or feed line installation problem. Typical problems causing desktop RF
problems include the following:
ɀ Lack of suitable baluns.
ɀ Improper feed line routing near antennas, or improperly designed antennas.
ɀ Antennas too close to the operating position.
ɀ Poor equipment cabinet design, such as non-bonded or grounded equipment
covers or panels.
ɀ Poorly designed low-level audio line shield entrances, such as shields allowed to
enter cabinets instead of grounding at the enclosure entrance.
ɀ Improper antenna feed line building entrance, lacking a properly grounded
entrance panel.
ɀ Rather than patching a system problem at the desk, it is much better to correct
the actual problem source.
Coaxial Line Isolators
The goal of every operating position is to maintain all equipment cabinets and housings
at the same RF potential. Never install coaxial line isolators between desktop radio
equipment. Isolators on or near the desk are contrary to this goal, and actually promote
or encourage RF potential differences between different desk equipment. If an RF
problem appears at the operating position, correction, repair, or replacement of
defective equipment is in order.
Proper line-isolator installation points are either just outside the operating room entrance
and/or close to the problem’s actual source. If the antenna system has excessive
common mode current on feedlines, the desktop has defective cables or connectors, or
if equipment has poor equipment cabinet design such as poor cover bonding to chassis,
locate and correct the actual problem.

15
Front Panel Controls
Figure 2 Front Panel
The front panel contains the following indicators and controls. To prevent damage,
become familiar with the front panel before operating the amplifier.
1. MULTIMETER Right scale FET Module Current, Voltage, ALC, and Reflected
Power. Left Scale Power Output. Multimeter (reflected power, module voltage,
ALC, or module current) selected by control 6.
2. BAND SELECT or REMote selector knob.
3. BAND INDICATOR or REMote backlit LE indicators, also warning if flashing.
4. ALC SET limit adjustment.
5. ALARM INDICATORS ALC, High SWR, PA Fault, and Transmit on.
6. MULTIMETER SELECTOR switch.
7. OPERATE/STANDBY switch, also resets fault warnings.
8. MAIN POWER switch, also resets power supply overload.
The meter’s left scale-arc (Figure 2, ref 1) continuously indicates forward peak envelope
power (PEP) output directly in watts. PEP has no fixed relationship to long-term average
power except, for constant amplitude carriers like a steady CW carrier, when PEP and
average powers are equal. PEP is the highest average power during one (or more)
radio frequency cycle(s) at the modulation envelope crest.

16
The meter’s rightmost scale-arc indicates PEP reflected power in watts on the upper
scale numbers and pickets. Notice power meter calibrations are not evenly spaced.
Lower scale numbers and pickets are evenly spaced, and are for all other functions. The
lower right scale is used for relative ALC setting, power amplifier module voltage (0-70
volts), and power amplifier current (0-70 amperes). Nominal voltage is 50 volts;
maximum safe current is 25 amperes. Maximum safe output is 600 watts peak;
maximum safe peak reflected power is 125 watts.
Back Panel Connections
Figure 3 ALS-70 Back Panel
POWER INPUT
The power supply must be unplugged from the power mains before installing or
removing this connector. This connector is indexed by a slight vertical offset in
the two round index pins. Observe spacing offsets to correctly mate the pins.
Seat the male plug fully onto the amplifier rear panel male connector pins. After
seating, the power supply can be plugged into the AC mains outlet.
ALC
Optional connection. Connects to radio ALC input and provides power limiting.
RELAY
Connect to radio amplifier keying line. Radio must pull this 14-volt 15-mA line
below 1-volt to transmit.
GND
Connect to station ground bus, if available. This connection is primarily for extra
safety.

17
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, and
should not be needlessly long.
RF OUT
To 50-ohm antenna, antenna tuner, or power meter. This is the high power
output. 50-ohm coaxial cable and system beyond this connector must safely
handle at least 600 watts.
RADIO INTERFACE
This connector is for use with Ameritron radio interface cables. It allows
automatic band selection (following the radio). It also provides amplifier actuation
in transmit mode with some radios.
REMOTE
These RJ45 connectors are for an Ameritron remote control head, or remote
operation with an interface box. They provide access to controls, including most
metering functions.
KEY LOOP
Key loop switch and jack are for use with certain automatic antenna tuners.
Instructions will be in tuner manual. Key Loop switch must be off when using
remote cable unless using this jack.
Interconnections
1. If you use a desktop grounding bus system, connect the station ground bus to the
amplifier’s rear panel wing nut. National safety codes require the station ground
electrically bond to the power mains safety ground at the building entrance. o
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 control port. This port is
usually described or defined in the amplifier interfacing section of the radio or
transceiver manual. This port must pull low for transmit, and be open circuit when
receiving. Relay control voltage from the ALS-706 is 14 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 600-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.

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5. Connect the IN connector to your transceiver. o 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 ne er use a tuner of any type on the amplifier input, nor should
you dri e this amplifier with o er 100 watts peak en elope power.
6. The ALC line is optional. In general, transceiver internal ALC is all that is
necessary. The ALC monitors the RF output power and reflected power supplied
by the ALS-706 to the load.
7. Operate the bandswitch manually during initial testing. o not connect band
decoders, band data lines, or computer interfaces until initial tests are completed
and the amplifier is functioning normally.
8. When using an automatic antenna tuner that has the capability to inhibit the
amplifier from operating either during tuning or when conditions are outside of the
tuner’s capability; and when the Radio Interface Cable that has the Amplifier
Relay line included (not using the RELAY jack); the KEY LINE can be used. The
KEY LOOP Switch is used to route the key signal from the interface to the amp
directly or out the KEY LOOP jack.
a. If the KEY LOOP is not used, set the KEY LOOP Switch to OFF so the
Radio Interface Cable can key the amplifier.
b. If the KEY LOOP is used with an automatic antenna tuner switch the KEY
LOOP Switch to ON, run a cable from the KEY LOOP connector on the
amp to the AMP ENABLE IN connector on the tuner, and run a cable from
the AMP ENABLE OUT connector to the RELAY connector on the amp.
Optional Radio Interface Cables
ALS-706/ALS-1406/ALS-1306/RCS-12 Radio Interface Cables available from
Ameritron.
Model No. Description Notes
DB-13D ICOM with ACC, 13-Pin DIN
DB-7DI ICOM with ACC 2, 7-Pin DIN
DB-DB7DK Kenwood with DB (except
TS-480)
SET Baud RATE 9600
TS-590 menu 53 (HF) 54 (50 MHz) #2,
TS-570 menu 3 (HF) and 40 (50
MHz)#2
TS-990 s menu 11 (HF) and menu 12 (50
MHz) set to 3= active high+relay+delay
TS-2000 menu 28A #2
DB-DB8MK Kenwood TS-480 Baud rate 600, menu 28 (HF) channel 2
and 2 (50 MHz) channel 2
DB-8MY2 Yaesu FT-
8 7/857/817/840/8 0/ 0/100
DB-8DY Yaesu with standard 8-Pin DIN
Band Data
DB-10MY Yaesu FT-450/ 50/1200
DB-DB15Y Yaesu FT-DX3000
DB-DB15HE Elecraft

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Table 2 Optional Radio Interface Cables
Operating Frequency Range
This amplifier covers all Amateur Radio frequencies below 54 MHz, as restricted by
FCC or your local governing authority. Once you have established proper connections,
please set the amplifier BAN SELECT control (Fig. 2, ref 3) to one of the following
bands:
Band Frequency Range Notes
160 1.8 – 2.3 MHz
80 3.0 – 5.0 MHz
40 5.0 – 9.0 MHz
30 9.0 –14.5 MHz USA 30-meter power limit 200 watts
20 9.0 – 14.5 MHz
17 14.5 – 22.0 MHz
15 14.5 – 22.0 MHz
12 22.0 – 30.0 MHz Amplifier automatically disables above 26 MHz
10 22.0 – 30.0 MHz Amplifier automatically disables below 28 MHz
6 50.0 – 54.0 MHz
Table 3 Band Frequency Ranges
Ca tion: This amplifier has an FCC mandated automatic disconnect and other features
preventing 27-MHz operation. There is no available circ itry or control provision to
circ mvent this locko t.
MARS or CAP Operation
For licensed amateur radio operators participating in Military Affiliate Radio Systems or
Civil Air Patrol, this amplifier is suitable for use on all frequencies between 1.8 and 54
MHz with some precautions. The amplifier will not function between 26 and 28 MHz due
to the required lockout. The upper frequency limits are in bold type in the table above.
o not operate above the bold-type frequency limits in the table above because PA
(power amplifier) or filter damage may occur.
This amplifier has significantly cleaner output purity than FCC part 97.307 requirements
when operated inside all amateur bands listed in the table above. Ameritron does not
guarantee harmonic suppression or operation in applications outside standard amateur
radio bands.
Most non-amateur services prohibit use of non-commercial radio equipment. This
amplifier automatically prevents operation between 26 and 28 MHz. Operation in the 26-
28 MHz range is not available with this product, irrespective of licensing or end-use.

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Warning Lights
The ALS-706 has two primary warning lights in the center of the front panel, SWR and
PA. When SWR or PA warnings illuminate from an operating fault the amplifier defaults
to a forced bypass mode. Operational faults and the forced bypass are reset by placing
the amplifier in standby.
ALC: The yellow ALC light is at the far left of the warning light cluster, next to the ALC
control. The yellow ALC light is not a fault indicator. The ALC light indicates ALC output.
Occasional flashing is normal with properly adjusted ALC. An almost steady ALC light
generally indicates too much ALC.
TX: The TX indicator illuminates steady green when the amplifier is “keyed” or in the
transmit mode.
The SWR and PA indicators serve exclusively as warnings. The SWR and PA, in
conjunction with TX and Band indicators, flash in certain “codes” to indicate severe
operational problems.
The following table applies to faults:
Warning
Light
Steady
Warning
Light Flash Fault Cause or Cure
SWR TX Antenna Reflected
Power
High antenna SWR or
intermittent antenna or feed line
connection
SWR, PA Band Wrong filter
Filter input SWR
Exciter or amplifier on
incompatible band, filter failure
PA, TX PA FET too hot Excessive power for duty cycle
or SWR, lack of proper airflow
10M, PA,
TX Illegal 11 meter Excessive 27 MHz signal level
REM, PA No data or bad band
data when on remote
efective or improper remote
cable, or bad radio band data
information
Table 4 LED Alarm Indicators