AMERITRON AL-572, Инструкция по эксплуатации

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Ameritron AL-572 Instruction Manual
18
This switch will also reset the grid protection circuit if an optional grid overload protection
circuit is installed. The overload circuit will be reset whenever this switch is placed in the
"STBY" position and returned to the "OPR" position.
"PLATE" Control
The "PLATE" control adjusts the output tank circuit to resonance. This control should always be
adjusted for maximum RF output power. Maximum RF output power normally occurs
simultaneously with maximum grid current and very close to the plate current "dip."
"LOAD" Control
This control adjusts the coupling of the amplifier to the antenna or load. This adjustment insures
optimum coupling between the tube and the load as the SWR of the load, the operating
frequency, or the power level is changed. Advancing the "LOAD" control clockwise increases
the RF power output capability and the linearity of the amplifier. Advancing the "LOAD"
control (clockwise rotation) also
decreases the grid current and increases the plate current for a
given amount of drive.
The efficiency of the amplifier and the grid current decrease if the "LOAD" control is rotated
beyond the point of maximum output. The linearity, however, will increase. The proper position
for this control is
slightly clockwise from the setting that produces maximum output with full
drive power applied to the input. Never use the "LOAD" control to adjust the output power.
Aways set power by reducing exciter power.
The "PLATE" control should always be checked after the "LOAD" control is adjusted by more
than one number. This is especially important at the high end of the "LOAD" range on 20 meters
and above. For example, if the "LOAD" is advanced from 7-1/2 to 8-3/4, the "PLATE" should be
re-tuned. If the "LOAD" is touched up only a slight amount, the "PLATE" setting will not
usually require re-adjustment.
ALC M
ETERING
, C
ONTROLS
,
AND
A
DJUSTMENTS
ALC Metering Functions
The "MULTIMETER" switch in the AL-572 has two positions that indicate the functioning of
the ALC circuit. These positions are as follows:
ALC
In this position the multimeter measures the output voltage of the ALC detector. The full scale
reading of the ALC detector voltage is 35 volts. It is read directly from the ALC/ HV scale of the
multimeter. The multimeter will indicate the maximum value of ALC voltage available from the
internal ALC circuit. The meter should flick upwards occasionally during normal ALC action in
this position.