AMERITRON ALS-500M, Instruction Manual

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ALS-500M Instruction Manual
4
Written assistance is also available. Due to time delays in processing mail, please allow a minimum of
three weeks for a written reply. Send questions to: Ameritron
, 116 Willow Road, Starkville, MS 39759
Export Modifications
A simple modification will allow operation on frequencies above 22 MHz. A parts kit to make this
modification is available by sending a written request for an 19-10600 export modification kit along
with a copy of your valid amateur license to the Ameritron. There is a charge for this kit. Export
models are shipped with this modification installed and have an "X" following the serial number.
INSTALLATION
Location
Do not locate this amplifier in excessively warm locations, near heater vents, or in unventilated areas
with ambient temperatures exceeding 120 degrees Fahrenheit. Be sure that air can circulate freely
around and through the amplifier cabinet. Do not obstruct the air inlet at the right front side of the
amplifier or the outlet air holes on the lower left side of the amplifier.
The best location for this amplifier is one that allows the meter to be easily read and the controls
accessed during operation. The length of each 13.8 volt high current cable is very important. Every
consideration should be given to keeping the high current battery lead lengths as short as practical.
This
includes the ground leads to the battery and the ground lead to the vehicle's chassis.
The lengths of the remaining low current power and control cables are not critical. The relay control
lead can be made from any good quality two wire cable. Low level audio type cables sold for stereo
and VCR use are ideal for the relay connection. The RF cables should be kept as short as practical.
Power Requirements
This amplifier requires 11-18 volts positive at low current (less than 4 amperes) for the control and bias
circuits. This is a non-critical voltage. The voltage applied to the low current control line will not affect
the performance of the amplifier if it is within the specified range. The control line is the small red
wire that connects between pin 10 of the power connector and the 5 ampere fuse.
The heavy RED conductors and the black battery return and chassis ground conductors must carry the
full peak current of the amplifier. This current can reach 80 amperes on voice peaks or 40 amperes of
average current. This large current is split between the two large RED wires leaving pins 3 and 4 of the
power connector. The ground connections from pins 11 and 12 must also carry this current. It is
extremely important to minimize the voltage drop across these conductors. For maximum performance,
all of the high current leads (including the ground leads) must be kept as short as possible.
The following chart gives the approximate peak voltage drop in volts per foot of a single supply wire
with 40 amperes of current. Remember the ground wires also carry high current. This chart assumes
that the chassis ground of the vehicle has negligible resistance, and that the negative lead to the battery
is the same wire gauge as the positive supply leads. The chart on page 5 indicates the maximum length
of each individual wire for full performance: