17
After the segment test, the 3 least significant digits of the
sensor serial number will be displayed for approximately
1 second. (When powering up in the ATTN mode, the
attenuator serial number is shown. This typically
matches the sensor S/N.) Verify that the displayed sensor
or attenuator serial number matches the serial number of
the sensor and attenuator being used.
If the Model 840-C is being powered up for the first time
after new batteries are installed or if the battery has deep
discharged, it will automatically enter a default mode of
operation. Note that the audio is turned off in the default
mode of operation. Otherwise the Model 840-C powers up
in the configuration it held when it was last shut off.
The following sections and Figure 6 provide a brief
description of the display, controls, and connectors.
3.3.1 Digital Display
The Model 840-C has a 4-digit backlit liquid crystal display
(LCD). The minus sign is displayed. The plus sign is
implied by the absence of the minus sign. The following
annunciators are displayed on the LCD.
+
—
Low battery indicator.
nW
,
uW
,
mW
, or
W
—
Nanowatts, microwatts,
milliwatts, or watt display
range selected.
dBm
,
dB
—
Decibels relative to 1 mW
(dBm) or decibels relative
to user set level (dB)
selected.
NOTE
When neither a watts-type or decibel-type annunciator is
displayed, the meter is performing a linear ratio refer-
enced to user set power.
RECALL
—
Establishing or using a user
set power.
AUTO
—
Autorange selected.
—
Background correction
selected.
—
Attenuator selected.
P-P
—
Peak-to-Peak measurement
selected.
Model 840-C
Controller
3.3
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