Page 12
VL-1000 Operating Manual
Drive Power Check
If this is first-time operation, or whenever
using a different exciter (transceiver), perform
this procedure to check peak exciter driving
power.
r
Turn the VL-1000 POWER switch on by
pressing the switch in.
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Make sure that the OPERATE and TUNER
switches on the VL-1000 are both off.
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Connect a 100-watt dummy load to the ANT
1 jack on the VL-1000, if available. If a
dummy load is not available, connect an
antenna which presents a 50
Ω
resistive
load to the ANT 1 jack. Tune your exciter to
a clear frequency.
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Set the transceiver to the CW mode, and
preset the D
RIVE
or R
F
P
WR
control on the
transceiver fully clockwise (maximum).
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Briefly key the transmitter, while watching
the display of the VL-1000. If the (indicated)
exciter power is above 100 watts, turn the
ATT switch ON.
Never press the ATT
switch while transmitting.
Drive power must be at least 50 watts for
accurate SWR detection, and 70 to 80 watts
for optimum tuner performance. Full power
output will be obtained from the VL-1000 when
the drive power is between 50 and 80 watts,
depending on the band in use. When the VL-
1000 power amplifier section is activated, ALC
voltage is fed back from the amplifier to the
transmitter, to reduce power output to this level.
However, much higher drive power to the am-
plifier will cause the protective circuitry to dis-
able the amplifier (to avoid damage to the in-
put circuits). Therefore, when using an exciter
delivering more than 100 Watts of drive power,
the input attenuator should be used. With
Yaesu transceivers, only the FT-1000/D se-
ries should require the use of the attenuator,
as the FT-1000/D is capable of up to 200 Watts
of output power.
ALC Alignment
When this amplifier is used with Yaesu
transceivers such as the FT-1000MP, FT-990,
or FT-920, the ALC system normally will not
require alignment. However, if it appears that
full power is not being achieved due to exces-
sive ALC action, you may align your VL-1000’s
ALC system to that of your transceiver via this
simple procedure:
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Connect the transceiver to the INPUT 1 jack,
and select “INPUT 1” via the front panel
INPUT switch.
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Set the RF output power to the HIGH power
condition via the front panel LOW switch.
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Press and hold in the INPUT switch for ½
second; this initiates the “ALC Alignment”
mode.
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Start with the transceiver’s D
RIVE
or R
F
P
WR
control fully counter-clockwise, then rotate
the D
RIVE
or R
F
P
WR
control to the fully clock-
wise position while transmitting.
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If the power output from the amplifier (as
displayed on the AVG meter) does not reach
1000W because of the effect of the VL-
1000’s ALC voltage at full exciter drive, keep
the transceiver’s D
RIVE
or R
F
P
WR
control
fully clockwise, then press and hold in the
DISPLAY 2 key until the power output from
the amplifier reaches 1000 Watts.
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If, on the other hand, the ALC voltage from
the VL-1000 does not cause the exciter
drive to be controlled such that the power
output from the amplifier limits at 1000
Watts, do the reverse procedure from that
just described. First, reduce the drive from
the exciter until the VL-1000’s power out-
put is 1000 Watts. Next, press and hold in
the DISPLAY 1 key until the output power
from the amplifier is just reduced from the
1000 Watt level. Now set the transceiver’s
D
RIVE
or R
F
P
WR
control fully clockwise, and
press the DISPLAY 1 key (to increase ALC
voltage/decrease power output) or DISPLAY
2 key (to decrease ALC voltage/increase
power output) until the power output from
the amplifier reaches 1000 Watts (these
tuning procedures should be as short as
Operation
