6
TUNE-UP
CW PROCEDURE
Follow the instruction in numerical order. If the various meter
readings are different than the instructions, check the
connections from the exciter to the amplifier and make sure they
are correct. Consult the manual for the exciter if necessary. Be
sure the transformer is correctly wired for your line voltage. See
the
POWER CONNECTIONS
instructions on page 4 for
wiring details.
1. Set the AL-811 front panel switches as follows:
OFF-ON
to
OFF
OPR-STBY
to
STBY
Ip-HV
to
HV
2.
Plug the line cord into the proper voltage outlet.
3. Set the power switch to the
ON
position. the meter lamps
should light and the fan should start. Read the 2000 volt
scale on the multimeter. It should indicate 1700 volts
nominal and no more than 1800 volts.
4. With the amplifier still on
STBY
, tune the exciter into the
normal 50 ohm load according to the manufacturer's
instructions. Turn the exciter drive fully down after tuning.
5. Place the amplifier bandswitch on the same band as the
exciter, the
PLATE
control in the dial range for the band
selected, and the
LOAD
control as indicated:
MHz Plate Load MHz Plate Load
1.80 1 3 10.0 7 0
1.90 2 4 14.0 8 1/2 4 1/2
3.5 4 1/2 3 18.1 8 1/2 4
3.7 5 4 21.0 9 5
4.0 5 1/2 4 1/2 24.5 4 8 1/2
7.0 7 1/2 4 1/2 28.5 9 1/2 5
7.3 7 1/2 4 1/2
6. With the exciter drive still at zero, place the
HV-Ip
switch
in the
Ip
position. Observe the 750mA scale. It should
read zero. Place the
STBY-OPR
switch in the
OPR
position.
7. Key the exciter (no drive). The Transmit
(XMT) LED
should light. Observe the plate current on the 750mA scale.
It should be 110mA.
NOTE: The no drive current will vary up to 25% due to
component and line voltage tolerances.
8. Apply only enough drive to indicate a grid current of
100mA OR an Ip of no more than 450mA. Tune the
PLATE
control for maximum output power. It is normal
for the plate current to dip at this point. If the grid current
goes over 150mA, reduce the drive at once. Unkey the
exciter.
9. Observe the output on an external RF wattmeter. Increase
the drive until full exciter power (never to exceed 100
watts) or 200mA of grid current is achieved. Quickly adjust
the
PLATE
and
LOAD
controls for maximum output
power.
10. Reduce the drive until the desired output levels are
obtained.
NOTE:
Rotating the
LOAD
control clockwise reduces grid
current for a given amount of drive. If the
LOAD
control is set at too low a numerical setting, a severs
stress on tank components may occur. The
PLATE
control should always be peaked for maximum grid
current or output power. Do not exceed 700mA of
plate current during tune-up.
(13 pages)
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