AMERITRON AL-572, Инструкция по эксплуатации

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Ameritron AL-572 Instruction Manual
21
D
RIVING
P
OWER
This amplifier is designed to operate at full ratings when it is driven by an exciter that has
approximately 70 watts of RF output. An exciter with a lower output power may be used with a
resulting decrease in amplifier output. Both the driving power and the "LOAD" control must be
carefully adjusted when using an exciter that delivers more than 70 watts. Proper control settings
will help prevent excessive grid current and spurious signals, which create needless interference
to other operators. A monitor scope is recommended for continuous output observation. An
oscilloscope is the best way of determining if the amplifier is "flat-topping" and producing
excessive distortion products.
A second method of determining linear operation is to monitor the peak RF output power
carefully on the AL-572's internal meter. Determine the maximum obtainable RF output power
and reduce the exciter's power until there is a noticeable margin from the maximum output
power. This will insure some reserve power is available for random voice peaks.
Note: Never increase the drive power beyond the point where the amplifier's output power
stops increasing. This is also the point where the grid current will begin rising
rapidly.
The amplifier is being over-driven for a given "LOAD" setting when the grid current increases
rapidly while the plate current and output power increase slowly. The amplifier "LOAD" control
needs to be
advanced to a higher number if this condition occurs. Non-linear operation, splatter,
and excessive grid current will occur if the "LOAD" setting is too low. Excessive plate current is
the proper indicator that the drive power limit has been reached.
T
UBE AND
C
OMPONENT
L
IFE
These guidelines will help prolong tube and component life, and minimize splatter.
1. On SSB or other linear modes virtually any amount of power will cause splatter if the loading
is too light ("LOAD" control too far counter-clockwise). Always tune for maximum output
with maximum drive power. Reduce the drive power to reduce the output power on SSB, not
the loading control.
2. Lightly loading an amplifier will also result in large voltages building up in the tank circuit.
Under-loading an amplifier is much harder on the tubes and other components than operating
a properly loaded amplifier into a high SWR or with excessive drive power. We recommend
slightly overcoupling the amplifier (loading control advanced slightly beyond the point of
maximum output) to insure the best linearity and freedom from arcing.
3. Never depend on average reading power or current meters to indicate proper operation on
SSB or other linear modes. The best indicator of linearity is either an oscilloscope or the
internal PEP RF output meter. Maximum linearity can be determined by finding the
maximum output power possible and then reducing the
exciter power for a slight reduction in
output power.
4. Never exceed 170 mA of grid current on CW carrier during actual operation. The proper grid
current for SSB will range from 0 to 75 mA. The SSB grid current will vary with the
operator's voice, the amount of signal compression or processing, and the tube characteristics.