I
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Power Keys
(ALC MODE
n)
(ALC
be changed.
Pressing the (ALC MODE
8)
key displays the current ALC mode and allows it to
When this key is pressed the current ALC mode is displayed in the
MARKER/SWEEP/STATUS area. The mode can be changed to the next choice
by pressing the key again, or by pressing the
a
QJ
keys. The ALC mode
choices are:
Internal
Leveling
Unleveled
The ALC point is inside the source. The displayed message
is
ALC=
I rit.
ern.3
1
.
The ALC circuitry is turned off. This will cause the UNLEV
annunciator to light. Provides uncalibrated level control by
allowing direct control of the internal linear modulators and
step attenuator. The modulator is set by using the front
panel knob or the
Q)
@J
key. A 1
dB
change in modulator
setting corresponds to an approximately 1
dB
change in
output power. The displayed message is
HLC:=l_ln
1
+Y...w
l&.
NOTE
If your sweeper has option
1El
(add step attenuator), the ALC and the attenuator are uncoupled when
your sweeper is in the following ALC modes. This will be indicated to you by the front panel display
annunciator,
UNCPLD.
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I
External Diode The ALC point is fed from an external diode detector. This
Leveling mode requires an external feedback connection from a
negative-output diode detector, at the leveling point, to the
instrument’s ALC IN BNC connector on the. front panel. To
obtain calibrated leveled power, the EXT CAL adjustment
should be made. (See
EXT
CAL
.)
The EXT ALC LED is
turned on. The displayed message is
ALi:=D
i
I:&.
Power Meter The ALC signal is coming from an external power meter.
Leveling This mode requires an external feedback connection from
the recorder output of a power meter, at the leveling
point, to the instrument’s ALC IN BNC connector on the
13-7
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General