Instruction manual

AL-800 Instruction Manual
26
The plate current (Ip) of the amplifier and the output power of the exciter should dip (decrease)
when this adjustment is made.
10b. If the ALC is not connected, place the exciter in the transmit mode and gradually increase the
drive until a grid current of 15 mA or a plate current of 0.3 ampere (whichever is higher)
appears. The
"PLATE"
control should be adjusted until maximum grid current and maximum
RF output power appear. The plate current (Ip) should now dip slightly. The drive power
should be removed.
11a. Increase the
"ALC SET"
voltage (if the ALC is connected) until 35 mA (7 volts) is indicated.
Apply full drive (not to exceed 100 watts) and adjust the
"LOAD"
and
"PLATE"
controls for
maximum RF output power. The grid current should not be allowed to go above 40 mA at this
stage. The plate current should not be allowed to exceed 1 ampere during brief periods of
tuning (30 seconds).
11b. Increase the exciter drive power (if the ALC is not connected) until 35 mA of grid current is
indicated. Adjust the
"LOAD"
and
"PLATE"
controls for maximum RF output power. The
grid current should not be allowed to go above 40 mA at this stage. The plate current should
not be allowed to exceed 1 ampere during brief periods of tuning (30 seconds).
12. For CW operation, the output power should be reduced with the
"ALC SET"
control until the
rated power of 850 watts CW is obtained. The
"LOAD"
control should be adjusted until
minimum plate current is obtained without dropping below 850 watts. The exciter's power can
be reduced until the multimeter shows a slight upward flicker with the
"MULTIMETER"
switch in the ALC position if the ALC is used.
13. For SSB operation, a two-tone generator or sustained "HEL-L-L-L-L-O" can be used. The
exciter should be set to produce the maximum output power (not to exceed 100 watts of peak
power). The amplifier's
"LOAD"
control is adjusted for maximum power on the internal peak
reading RF wattmeter. The
"ALC SET"
control is adjusted until a peak power output of 1200
watts (or less) is obtained. Finally the exciter's audio gain or output power is adjusted until the
multimeter
"ALC"
position indicates the desired ALC level.
Note: If the ALC is not connected, the amplifier should be fully loaded with maximum drive (not
to exceed 100 watts). The exciter's output should then be reduced until 1200 watts is
obtained.
QSK Operation
The antenna transfer relay in the AL-800 takes approximately 15 milliseconds to change states.
This precludes using the standard internal relay for QSK CW operation. Commonly available
vacuum relays are specified at 5 to 7 milliseconds of switching time. Even expensive vacuum relays
are less than ideal for high speed QSK operation. At 60 WPM, less than 50% of the receive-time is
available with vacuum relays.
On PACKET, AMTOR, and other modes, delay can be added to the transmit and receive
changeover to use either vacuum or our standard relay effectively. Ameritron offers two high-speed