AMERITRON ALS-600 User manual

AMERITRON ALS-600/S
600 WATT NO TUNE
TMOS-FET AMPLIFIER
INSTRUCTION MANUAL
AMERITRON
116 WILLOW ROAD
STARKVILLE, MS 39759 USA
662-323-8211
Revision 6a

Table of Contents
ALS-600 Specifications…………………… …………………………………………. 4
Optional Accessories…………………………… …………………………………. 5
ALS-600 Features............................................................................................................6
Power Supply Features....................................................................................................8
ALS-600PS..........................................................................................................8
ALS-600SPS........................................................................................................8
ALS-600PS and ALS-600SPS.............................................................................8
General Information.........................................................................................................9
Amplifier..............................................................................................................9
Power Supply.......................................................................................................9
Export Modifications...........................................................................................10
Amplifier Circuitry..........................................................................................................10
Wattmeter Circuits...............................................................................................10
ALC (Automatic Level Control)..........................................................................10
Thermal Overload................................................................................................11
Load Fault Indicator.............................................................................................12
SWR Considerations............................................................................................12
Power Supply Circuitry (ALS-600PS)............................................................................13
Line Voltage Modifications.................................................................................13
High Voltage Section...........................................................................................14
Primary Circuit.....................................................................................................14
Low Voltage Circuits...........................................................................................14
Switching Power Supply Circuitry (ALS-600SPS).........................................................15
Line Voltage.........................................................................................................15
High Voltage Section...........................................................................................16
Primary Circuit.....................................................................................................16
Low Voltage Circuits...........................................................................................16
Installation........................................................................................................................16
Amplifier Location...............................................................................................16
Power Supply Location........................................................................................16
Grounding............................................................................................................17
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Power Requirements............................................................................................17
Interconnections...............................................................................................................18
Operation..........................................................................................................................20
Duty Cycle Considerations… …………………………………………..20
ALC Set-Up……………………………………………………………………..20
SSB Operation.....................................................................................................20
CW Operation......................................................................................................21
RTTY, FM and Other High Duty Cycle Operation.............................................21
AM Operation......................................................................................................22
Drive Power Requirements..................................................................................22
ALS-600 Remote Control Operation and Automatic Band Tracking.................24
ALS-500RC Remote Control Operation..............................................................25
ARI-500 Automatic Transceiver Frequency Tracking........................................25
Periodic Maintenance...........................................................................................25
Technical Assistance........................................................................................................26
ALS-600 Parts Lists & Schematics..................................................................................27
Meter/ALC Board................................................................................................27
PA Board..............................................................................................................29
Output Filter Board..............................................................................................30
LED Board...........................................................................................................34
SWR Detect Board...............................................................................................35
ALS-600 Chassis Components............................................................................36
ALS-600PS Parts Lists & Schematics.............................................................................38
Power Supply Board............................................................................................38
ALS-600PS Chassis Components........................................................................39
ALS-600SPS Wiring Diagram.........................................................................................40
ALS-600SPS Schematic .................................................................................................41
3

ALS-600 SPECIFICATIONS
Output Power: 600 Watts PEP SSB, 500 Watts CW typical
Frequency Coverage: 1.5 to 22 MHz (10/12 Meters with MOD-10MB)
Driving Power Required: 100 watts maximum
Input SWR: 1.5:1 maximum
Spurious Outputs: Greater than 45 dB down
Intermodulation Distortion: Greater than 25 dB down
SWR Protection: Amplifier is bypassed if reflected power exceeds 75
watts. Prevents amplifier damage if you select the
wrong band or wrong antenna, or have high SWR
Over Power Protection: If output forward power or reflected power exceeds
safe level, output power is automatically reduced by
controlling the exciter ALC.
Metering (ALS-600): Illuminated Cross-Needle SWR/Wattmeter -- lets you
read SWR, and forward and reflected peak power
simultaneously
Metering (Power Supply): Illuminated Cross-Needle Meter monitors voltage and
current of 50 VDC line.
Operate/Standby Switch: Lets you run "barefoot", or instantly switch to full
power.
ALC Controls: Front Panel - exclusive Ameritron feature -- lets you
adjust your amplifier output power.
Rear Panel – sets ALC range to match your
transceiver.
T/R Relay Drive Rqmts: Must support 12VDC at 100ma maximum, ground to
enable
Indicators: Transmit, ALC and Load Fault LED indicators to keep
you informed.
Accessory Power: Rear panel 12 VDC/200 ma RCA-type output jack for
powering low current accessories.
4

Power Supply: Separate ALS-600PS or ALS-600SPS power supply
can be placed conveniently out of the way and
plugged into your nearest 120 VAC outlet -- no
special wiring needed. Supplies 50 VDC at 25 amps
to ALS-600 amplifier.
The ALS-600PS includes an exclusive Multi-Voltage
Power Transformer to compensate for stressful high
line voltage and performance robbing low line voltage.
Both the ALS-600PS and ALS-600SPS power
supplies can be configured for 120VAC or 240VAC
operation.
Step-Start Current Inrush Protection extends the life
of power supply components.
Power Requirements: 100-130VAC or 220-250VAC, 50/60 Hz. Wired for
120VAC. The ALS-600PS draws less than 12 amps
at 120VAC, and less than 6 amps at 230 VAC. The
ALS-600SPS draws less than 14 amps at 120VAC,
and less than 7 amps at 240VAC
Dimensions (ALS-600): 6"H x 9.5"W x 12"D (takes up less desktop space than your
transceiver)
Dimensions (Power Supply): 6"H x 9.5"W x 14”D -- can be placed conveniently out-of-
way.
Weight (ALS-600): 12.5 pounds
Weight (ALS-600PS): 32.5 pounds (linear power supply)
Weight (ALS-600SPS): 10 pounds (switching power supply)
OPTIONAL ACCESSORIES
•MOD-10MB Modification Kit for 10/12 meters
•QSK-5 High Power Pin Diode T/R Switch
•ALS-500RC Remote Control Head for ALS-600 (Ser. No. 14378 and higher)
•ARI-500 Automatic Band Switch for ALS-600 (Ser. No. 14378 and higher)
- ARI-500 Interface Cables. Check with Ameritron for pre-made cables for
popular transceivers.
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•ARB-704 Amplifier-to-Transceiver Interface
PNP-8D cable for FT-1000, (MP), 900, 767GX, 920, 990, 747GX
PNP-8M cable for FT-890, 840, 817, 857/D, 897/D
PNP-35 cable for FT-100/D
PNP-5M cable for FT-847
PNP-7D cable for TS-440, 690, 450, 180, 140, 950, 130, 870, 2000,
50, 120, 530, 430, 830, 949, 570
PNP-13D cable for IC-706/703/7000 series
PNP-7DK cable for TS-930
PNP-8MK cable for TS-480
PNP-5D cable for FT-980
PNP-8DI cable for ICOM ACC Jack
Check with Ameritron for additional cables as they become available
ALS-600 AMPLIFIER FEATURES
Rugged devices. The ALS-600 uses four rugged MRF-150 RF power FETs
All solid-state means instant warm-up. No-wait amplifier operation.
No tune operation. No tuning is necessary. A simple one knob band selector switch
permits operation on frequencies between 1.5 and 22 MHz (24-30 MHz with MOD-
10MB Modification Kit for 10/12 meters).
ALC protection. The output and reflected power levels control the exciter ALC voltage.
This helps prevent damage to the amplifier.
Front panel ALC control. This unique Ameritron feature allows easy front panel
adjustment of the ALC threshold to control power output.
Load Error Protection. The PA load impedance is monitored and the amplifier is
bypassed if the band switch or the external load is incorrect.
Illuminated Power/SWR meter. The ALS-600 has an illuminated cross-needle peak
reading RF power meter. Accurate directional coupler and peak storage circuits give
simultaneous forward and reflected peak power readings while simultaneously indicating
load SWR.
Operate/Standby switch. This switch allows the amplifier to be by-passed for "barefoot"
operation without turning the main power switch off and on.
Transmit, ALC and Load Fault Indicator LED's. Front panel LED's provide an
indication of amplifier status during operation.
12 volt auxiliary jack. This jack supplies +12v at 200 ma to operate low current
accessories.
6

Thermal Overload Protection. The transmit relay in the amplifier is disabled if
excessive heatsink temperatures are reached.
Compact size. The ALS-600 weighs only 12.5 pounds and measures 6"H x 9.5"W x
12"D.
Remote Amplifier Operation. The ALS-600 amplifier can be tucked out of the way
when used with the optional ALS-500RC Remote Control Head. The ALS-500RC
provides band switching, transmit and load fault indicators, output power monitoring, and
fault re-setting in a compact control and display unit.
Automatic Transceiver Frequency Tracking. The optional ARI-500 Automatic Band
Switch unit interfaces frequency band information for most transceivers to the ALS-600.
So as you change frequency bands on your transceiver, the ALS-600 automatically
follows these band changes. The ARI-500 may be configured for automatic fault re-
setting of the ALS-600 if desired. These features make the ARI-500 particularly
convenient for contest operations. The ARI-500 Automatic Band Switch includes an
input for the ALS-500RC Remote Control Head, so both may be used simultaneously if
desired.
7

POWER SUPPLY FEATURES
ALS-600PS
Multi-voltage heavy duty transformer. 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.
Choke input filtering. The ALS-600PS standard power supply uses an input choke to
provide a low power factor to the power lines. This reduces the peak currents drawn from
the line and improves the voltage regulation of the supply.
ALS-600SPS
Light weight. The ALS-600SPS is a light weight switching power supply to use with the
ALS-600 amplifier. It is 1/3rd the weight of the ALS-600PS linear power supply. The
ALS-600 amplifier with the ALS-600SPS switching power supply is ideal for travel.
Hash free. The specially designed switching and filter circuit makes the power supply
hash free.
Simple power line voltage options. The power supply will safely operate from 90-135
VAC in the 120 VAC setting, and 185-260 VAC in the 240 VAC setting.
ALS-600PS and ALS-600SPS
Step-start circuit. This circuit uses a relay and resistor to limit the inrush current to the
power supply. This circuit extends the life of the power supply components.
Current and output voltage metering. An illuminated cross needle meter monitors the
output voltage and current of the 50 volt output line.
8

GENERAL INFORMATION
Amplifier
The Ameritron ALS-600 is a 600 watt nominal output, solid state, linear amplifier using
state-of-the-art, high voltage, RF TMOS FET devices in the power output section. The
ALS-600 provides continuous frequency coverage from 1.5 through 22 MHz with no
tuning required. Broad-band 5 pole low pass filters provide output harmonic suppression
in excess of all FCC requirements. The MOD-10B kit provides operation up to 30 MHz
(copy of a valid amateur license is required to purchase the MOD-10B).
The ALS-600 uses four MRF-150 FET's operating at 50 volts in a double ended push-
pull parallel output configuration. High quality RF components combine with an
accurate peak detecting directional coupler, front panel adjustable ALC circuit with
automatic SWR foldback, and one switch frequency selection to make this one of the
easiest to operate amplifiers available. The matching power supply, an ALS-600PS or
ALS-600SPS, is shipped factory wired for 120 volt, 50/60 Hz power mains. The power
supplies are easily converted to other supply voltages between 100 and 240 volts.
Low Pass Filter Selection
Low pass filter networks must be selected for the different HF frequency ranges in order
to meet FCC requirements. The ALS-600 uses relay-selected low pass filter networks to
permit the selection of the proper filter networks by three different methods:
•The FREQ switch on the front panel of the ALS-600
•The band switch on the optional ALS-500RC Remote Control Head
•Automatically by the optional ARI-500 Automatic Band Switch
Power Supply
The ALS-600PS power supply is designed to power the ALS-600 amplifier from 50 to 60
hertz AC power mains that range from 100-130 VAC and 210-240 VAC. The ALS-
600SPS has a terminal strip where the AC voltages can be selected as either 120 or 240
volts 50/60 Hz, and will safely operate from 90-135 VAC in the 120 setting, and 185-260
VAC in the 240 VAC setting. All ALS-600PS/ALS-600SPS supplies are wired for
standard 120 volt systems and are shipped with a NEMA 5-15P three wire plug.
Both power supplies provide the power required to operate the ALS-600 in typical
continuous amateur service at 600 watt output levels. The ALS-600PS/SPS power
supplies provide the three DC voltages required by the amplifier unit. The high voltage
section supplies approximately 50 volts at a load current of 25 amperes.
9

10/12 Meter Modification
A simple modification allows operation on frequencies up to 30 MHz. A parts kit to
make this modification is available by sending a written request for the MOD-10MB
modification kit, along with a copy of your valid amateur license to Ameritron. There is
a nominal charge for this kit. Export models are shipped with this modification installed.
The ALS-600(S)Y is the export model for 115-130 VAC operation and the ALS-600(S)X
is the export model for 220-240 VAC operation.
AMPLIFIER CIRCUITRY
Wattmeter Circuits
The BIAS/WM/ALC board contains the peak power detector circuits. The rear panel
directional coupler connects to IC101D/C. IC101D/C drives Q101/102 to charge
C103/106 to the peak voltage from the directional coupler. C103/106 is lightly loaded by
IC101A/B and R103/107. This allows enough "hang" time for the meter to accurately
indicate peak power levels.
Accurate forward peak power readings are obtained under mismatched load conditions
when the reflected power is deducted from the forward power readings.
The average and peak envelope power values are EQUAL on CW, FSK and FM (modes
that do not have amplitude changes in the carrier). The average power level of voice or
other complex waveform signals has NO SET RATIO of peak to average power.
ALC (Automatic Level Control)
The ALC circuit functions by using a comparator (IC103A) to reduce the exciter drive
power if the output power of the ALS-600 exceeds a preset value. The ALC circuit also
reduces the drive power if the SWR increases while operating with the ALC controlling
the amplifier output power level. The ALS-600 ALC output should be connected to the
proper exciter external ALC connection point with a shielded audio type cable. Consult
the exciter manual for the proper exciter connection details.
Operation at high audio gain levels on SSB with ALC has the same effect as an RF
speech compressor. RF compression increases SSB "talk power". Background noise
pickup also increases when the exciter gain is operated at high levels to increase
compression. Audio distortion does not normally occur with this type of speech
processing if the ALC circuit in the exciter is properly designed.
Do not attempt to limit the CW power more than a few percent solely with the amplifier
ALC circuit. Using the amplifier ALC to reduce CW power levels may result in pumping
of the output power during dots and dashes. The "ALC SET" control will be correctly
10

adjusted when the "ALC" LED gives a small flash while transmitting on CW. This can
be accomplished by adjusting the "ALC SET" control on the front panel so that the
"ALC" LED just barely lights when the desired power level (500 watts maximum) is
reached with a steady carrier.
The ALC circuit can be used to reduce power by any amount on constant amplitude
carrier modes such as RTTY or FM. The ALC cannot cause modulation distortion or
pumping on these modes.
Never use the ALC to control the level of AM transmissions. Using the amplifier's ALC
circuit to control AM output power will cause pumping of carrier amplitude on AM
transmissions during modulation.
The ALC indicator on the front panel of the ALS-600 is driven by comparator IC3B.
Resistors R24 and R25 set the turn-on level of the front panel "ALC" indicator. Factory
selected resistor values cause the "ALC" LED to illuminate as soon as negative ALC
voltage begins to appear at the ALC output jack.
If the exciter used with this amplifier does not "fold back" until appreciable ALC voltage
is developed, the "ALC" LED may become fully lit even under operating conditions that
are producing very light ALC action.
Caution: There are no industry standards for transceiver or exciter ALC input voltage
levels, input resistance, or attack and decay times. While every attempt has
been made to make the ALC circuit in this amplifier compatible with various
exciters, the exact operation of the ALC circuit will vary with the exciters
response to external ALC control voltages. This ALC circuit will function
with negative voltage ALC control systems requiring less than 10 volts.
Thermal Overload
The ALS-600 has a built in thermal cut-out that by-passes the amplifier if excessive heat
sink temperature is produced. This circuit minimizes the risk of excessive temperature
damage to the FET's and other components.
If the amplifier "XMT" LED remains lit while the amplifier suddenly stops transmitting,
the thermal overload has probably tripped. If the thermal overload has tripped, full
exciter power will appear on the RF output meter.
The thermal overload resets automatically and all amplifier functions are restored when
heat sink temperature returns to a safe value. The usual cause of thermal overload is
excessive heat buildup during a transmission period longer than a few minutes. To
correct this condition, be sure that the power level and duty cycle limits are being
followed, the SWR is as low as possible, and cooling is not being hampered by air flow
restriction or excessive inlet air temperatures.
11

Load Fault Indicator
The "LOAD FAULT" LED indicator will light and the amplifier will be bypassed if the
band switch is set on the wrong frequency range, if the load SWR is excessive, or if the
output power level is excessive.
To reset a "LOAD FAULT" indication:
1. Determine and correct the cause of the problem.
2. Place the amplifier "STANDBY-OPERATE" switch to "STANDBY" and then
back to "OPERATE".
Note: When the ARI-500 is used, the STANDBY-OPERATE switch is under control of
the ARI-500. The amplifier will automatically be put in OPERATE when the
transceiver is keyed, regardless of the STANDBY-OPERATE switch position on
the ALS-600. When a fault occurs, the ARI-500 can be configured to
automatically re-set the ALS-600 after approximately 5-seconds. If the ARI-500
is not configured for automatic amplifier fault re-set, you must cycle the amplifier
power switch OFF and then ON to re-set the fault circuitry.
Note: When the ALS-500RC Remote Control Head is used (with or without the ARI-
500), the STANDBY-OPERATE function is controlled by the POWER OFF-ON
switch on the ALS-500RC.
The load fault detector circuit is located on the output filter board and measures the
reflected power presented by the output filter network and the SWR directional coupler.
The sensitivity of the circuit is adjusted by R304 and R601. C324 is a factory adjustment
that controls the impedance of the detector circuit. This capacitor is adjusted for
minimum detector voltage on 7 MHz with a 50 ohm load. Do not adjust any components
in this circuit without consulting the factory.
SWR Considerations
A high SWR (Standing Wave Ratio) causes higher voltages and/or currents to appear at
the output connector of the amplifier. This problem occurs with all amplifiers regardless
of whether tubes or semiconductors are used in the output stage.
Vacuum tube amplifiers have the reputation of handling a high SWR quite well. This
reputation probably exists for two reasons: First, most vacuum tube amplifiers use
adjustable output networks. Second, nearly all vacuum tubes handle momentary
overloads extremely well.
In tube amplifiers with tunable Pi or Pi-L networks, the only components affected by a
high load SWR are those between the loading adjustment capacitor and the output
connector. When the output network is properly adjusted, the SWR cannot affect tube
life.
12

The TMOS FET devices used in the ALS-600 have nearly the same momentary overload
tolerance as vacuum tubes. The low pass output network in the ALS-600 is much
broader in bandwidth and less sensitive to load changes than the networks used in tube
type amplifiers.
This makes the ALS-600 much less sensitive to frequency and SWR changes than the
best "no- tune" tube amplifiers but not as good as adjustable pi-networks. The ALS-600's
multiple section output network and push-pull output configuration offers much better
harmonic suppression than most tube amplifiers regardless of load SWR.
The only danger presented by a high SWR in this amplifier is that the current and power
dissipation in the output devices may exceed safe limits. Lengthy operation with high
SWR at high power levels can result in heat damage and failure of the FET devices. If
the reflected power exceeds 50 watts the power level should be reduced until the reflected
power indicated on the internal meter is 50 watts or less on peaks. At approximately 75
watts of reflected power the internal safety circuitry will disable the amplifier.
ALS-600PS POWER SUPPLY CIRCUITRY (ALS-600PS)
Line Voltage Modifications
The line input voltage of the ALS-600PS can be changed by moving jumper wires on the
power supply printed circuit board to new locations. The ALS-600PS is wired for
standard 120 VAC operation unless otherwise indicated.
Warning: Never unplug the power cable from the amplifier while the power supply
is connected to the power line. AC power line voltage is present on the
power cable connector pins.
Warning: Never remove the cover of the power supply while it is connected to the
power line.
Refer to the following chart for the proper location of the primary wiring. This chart lists
the proper jumper connections for different ranges of MAXIMUM line voltage.
It is always best to carefully measure your AC line voltage prior to setting the voltage
strapping.. The standard line voltage in the USA is NOT 110 and 220 volts. It is almost
ALWAYS above 120 volts or 240 volts.
Caution: Never exceed the voltage in this chart for each wiring configuration. If the
output voltage of this supply exceeds 65 volts, damage to the amplifier may
occur.
13

ALS-600PS Power Supply Board
Jumper Pad Diagram For the following line voltages jumper the correct pads.
AC LINE
VOLTAGE
RANGE PRIMARY BUCK BOOST
95-110 A TO B C TO D E TO 2 F TO 1
105-120 A TO B C TO D E TO F
115-130 A TO B C TO D E TO 1 F TO 2
200-220 B TO C E TO 2 F TO 1
210-230 B TO C E TO F
220-240 B TO C E TO 1 F TO 2
High Voltage Section
The high voltage section of the ALS-600PS uses a full wave bridge rectifier. DC filtering
is accomplished with a large swinging choke (T1) and a high quality computer grade
capacitor (C5). A pair of 100 ohm resistors (R5,6) absorb enough bleeder current to
prevent the output voltage from soaring under low load currents. The output voltage and
current of this section are monitored by a illuminated dual needle meter (M2a/2b).
Primary Circuit
10 ohm resistor (R602) limits the line current during the filter capacitor charge time to
lower the stress on the power supply components. When the 14 volt control line
approaches full voltage relay (RLY601) bypasses the 10 ohm resistor (R602) and applies
full line voltage to the transformer primary. The 10 ohm resistor is protected from supply
shorts by a 2 amp slow-blow fuse (F601) during the start-up.
A separate 10 volt transformer winding can be connected to either oppose or add to the
power line voltage. This allows the 115 volt maximum voltage primary windings to be
adjusted to provide the proper voltage. Use of the buck-boost winding allows maximum
primary voltages of 100, 110, or 120 volts maximum voltage or 210, 220, and 230 volts
maximum voltage at either 50 or 60 hertz.
14

The primary circuits are fused by two fuses (F1, F2) that are rated at 15 amperes at 100
volts, 12 amperes from 110 to 120 volts or 8 amperes from 220 to 240 volts. Since the
current demand and the power factor of this supply are so low Ameritron does not
recommend operating this supply on the higher voltage lines (210 to 240 volts) unless
lower voltages are unavailable.
Low Voltage Circuits
The low voltage power supply sections supply 14 volts positive at 2 amperes maximum
with a full wave grounded center tap supply for 'control, lights and also to power the bias
voltage regulator and the circuitry of the Bias/Wattmeter board in the ALS-600. This low
voltage circuit is protected by a 2 ampere fuse (F602) located on the power supply
printed circuit board.
A separate half wave rectifier supplies the low current necessary to operate the ALC
circuitry in the ALS-600. This circuit is protected by a 10 ohm 1/4 watt resistor (R601).
15

SWITCHING POWER SUPPLY CIRCUITRY (ALS-600SPS)
Line Voltage
The input AC line voltage for the ALS-600SPS can be changed by moving jumpers
located at the front of the unit under the current and voltage meter. The ALS-600SPS is
factory wired for 120 VAC operation unless otherwise indicated.
Warning: Never unplug the power cable from the amplifier while the power supply
is connected to the power line. AC power line voltage is present on the
power cable connector pins.
Warning: Never remove the cover of the power supply while it is connected to the
power line.
Refer to the picture (shown in factory wired 120V position ) for the proper location of the
jumpers. The 120V position (A5 to A6 and A2 to A1) will allow the power supply to
work from 90-135 VAC. The 240V position (A5 to A4 and A2 to A3) will allow the
power supply to work from 185-260 VAC. To change the power supply from 120V to
240V, unplug the connector from A6 and install it on A4 then unplug the connector
from A1 and install it on A3.
16

High Voltage Section
The High voltage section of the ALS-600SPS uses high current switching circuit with
superior filtering to produce a high current DC voltage. This line is protected by F1 on
the printed circuit board.
Primary Circuit
A 10 ohm resistor limits the line current during start-up, which lowers the stress on the
power supply components. When the –14 volt control line approaches full voltage, a
relay bypasses the 10 ohm resistor and applies full line voltage to the primary. The 10
ohm resistor is protected from supply shorts by a 2 amp slow blow fuse during start-up.
An input over-current circuit will disable the power supply at approximately 16 amps of
input AC current.
The primary circuits are fused by two fuses located on the back panel of the switching
power supply. The fuses are rated at 15 amps on 120 volts, or 8 amps on 240 volts.
Low Voltage Circuits
The low voltage power supply sections supply 14 volts positive at 2 amperes maximum
for control of lights, bias voltage regulator and the Bias/Wattmeter board in the ALS-600.
A separate 12 volts negative supply is used to operate inrush relay and the ALC circuit of
the ALS-600.
INSTALLATION
Amplifier Location
Do not locate this amplifier in excessively warm locations, near heating vents or near
radiators. Be sure that air can circulate freely around and through the amplifier cabinet.
Do not obstruct the air inlets at the rear of the amplifier and the outlet air holes on the
lower right side of the amplifier cabinet.
The best location for the amplifier is one that allows the meters to be easily read and the
controls accessed during operation. The length of the interconnecting control and ALC
cables are not critical. These should be made from good quality shielded cables. Low
level audio cables, sold for use with home theater equipment, are ideal. The RF input and
output cables should be kept as short as possible.
Power Supply Location
The best location for the power supply is one that is away from devices that are sensitive
to magnetic fields. The meter should be visible and fuses should be accessible for
17

service. Do not obstruct the air inlets at the rear of the power supply and the outlet air
holes on the upper right corner of the power supply cabinet.
Caution: The choke in the ALS-600PS power supply emits strong magnetic fields.
Never place magnetic tapes, computer disks or other magnetic sensitive
devices within 18 inches of the cabinet of the ALS-600PS.
Grounding
The station ground buss should be connected to a good earth and RF ground. Use the
heaviest and shortest connections possible. The best ground leads are smooth and have a
large surface area. Braiding (including standard coaxial cable shield) has a higher RF
resistance and should be avoided unless the lead needs to be flexible. The best
conductors for ground connections are copper flashing or copper foil. Solid copper wire
can be used and will closely approximate copper flashing if multiple ground leads are
used and separated at least a few inches. Water pipes can be used for an earth connection
if the plumbing is composed of all metallic pipes. The water meter or any other
insulated junction should be bypassed with a jumper wire clamped to the pipe at both
sides of the meter.
Multiple ground connections are superior to a single ground connection. Ameritron has a
technical information sheet with additional suggestions for grounding. No grounding
terminal is provided for the power supply since it does not generate any RF signals. A
safety ground is provided by the power line neutral ground through the line cord and
plug.
Warning: Never remove or defeat the electrical safety ground connection on the
power supply plug or a shock hazard may develop.
Power Requirements
Caution: The ALS-600 is not designed for operation from a 12 VDC power source.
The ALS-600PS/SPS power supplies are designed to match the ALS-600 amplifier.
They provides 50 volts DC at 25 amperes along with 12 volts positive and negative at
low current for the control and bias circuits of the amplifier.
The ALS-600PS linear power supply requires less than 12 amps at 120 VAC, or less than
6 amps for 240 VAC. The output voltage of the ALS-600PS supply should be kept
below 65 VDC at no load for maximum component life. If the no load output voltage of
the ALS-600PS exceeds 65 VDC, you must change the input line voltage of the ALS-
600PS. Refer to the "Line Voltage Modifications" section in this manual. The ALS-
600SPS switching power supply requires less than 15 amps at 120VAC, or less than 8
amps at 240 VAC. The ALS-600SPS no-load voltage should stay within one-volt of 50
volts.
18

INTERCONNECTIONS
1. Connect the RF (antenna) output of the exciter to the RF IN (SO-239) of the ALS-600
with a good quality 50 ohm cable capable of handling 100 watts.
2. Connect the station antenna system to the RF OUT (SO-239) connector with good
quality 50 ohm coax that will safely carry 600 watts.
3. Use shielded audio-type cable with standard male phono (RCA) connectors to
connect the RELAY jack of the ALS-600 to the transceiver or transmitter normally
open amplifier relay terminal. This connection has 12 volts open circuit and supplies
less than 100 mA of current when pulled to ground. There is a back pulse canceling
diode in the amplifier for exciter protection.
Note: The Ameritron ARB-704 Amplifier-to-Transceiver Interface provides plug-
and-play control between almost any transceiver solid-state or relay keying outputs,
and any Ameritron amplifier using transceiver-specific plug-and-play cables.
Note: The Ameritron ARi-500 Automatic Band Switch provides a low level keying
interface between your transceiver and the ALS-600s. Refer to the ARI-500 manual
for more information.
4. Connect the ground stud (GND) on the amplifier to the station ground buss with as
short a lead as practical.
5. Connect the ALC jack to the exciter ALC terminals with a shielded audio-type cable
using standard phono connectors.
Note: The Ameritron ARB-704 Amplifier-to-Transceiver Interface provides the ALC
interface for transceivers where ALC is only available through their accessory
socket.
6. Connect the female power connector from the ALS-600PS/SPS supply to the multi-
pin male connector on the ALS-600 rear chassis.
7. The 12V connector can be used to supply 12-14 VDC at less than 200 ma for station
accessories.
Note: If using either the ALS-500RC Remote Control Head or the ARI-500 Automatic
Band Switch, refer to those manuals for interconnection information with the ALS-600.
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