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 LDMOS 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 VDC. 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
Summary of Contents for ALS-706
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