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SECTION 14. INSTALLATION AND MAINTENANCE
14.1
FROM THE
ENVI
The normal
tal
variables of concern
are
and moisture. The standard
21X
is
designed to
operate reliably from -25 to
+SOoC (-55
to +80oC, optional)
in
noncondenging
humidity. When humidity
tolerances 4re exceeded, damage
to
lC chips,
microprocegsor
failure, and/or
measu
rement
inaccuracie$ due to condensation on
the
various PC board runners may
result.
Etfective
humidity
coftrol
is
the responsibility
of
the
user.
The
21X is rfot hermetically
sealed. Two
half
unit
packet! of
DESI PAK desiccant
are located
by
the
battefies. This
desiccant
should, in most
cases,
keel
the interior components dry
between battery
changes.
A
dry package
weighs
appfoximately
19
grams and
willabsorb
a maximum of six grams of water
al40o/o
humidity
anfl
11
grams at
80%.
Desiccant
packets
caribe
dried out by placing
the packets
in
an oven
4t 120oC for 16 hours (desiccant
only,
not thE
21X).
Campbell Scientific offers
two enclosures for
housing
a21X and peripherals.
The fiberglass
enclosures are
classified as NEMA 4X (water-
tight,
dusttight, corrosion-resistant,
indoor and
outdoor
use). A
1.25" diameter entry/exit
pot't
is
located
at
the bottom
of
the enclosure for
routing cables and
wires. The
enclosure
door
can be fastened with the hasp for easy access,
or with the two supplied screws
for more
permanent
applications, The white plastic
inserts
at
the
corners
of
the enclosure must be
removed
to insert the
screws.
Both enclosures
are white
for reflecting solar radiation, thus
reducing
the internal enclosure temperature.
The Model ENC 10/12 fiberglass enclosure
houses
the 21X and one peripheral such as
a
Storage
Module.
Inside dimensions
of
the ENC
1O112
are 12"x10"x4.5", outside dimensions are
16"x1
1.5"x7" (with brackets);
weight is 8.5
lbs.
The Model ENC 12l14 fiberglass enclosure
houses the 21X and one
or more peripherals.
lnside dimensions of
the ENC 12/14 are
14"x1
2"x5.5", outside dimensions are
18"x13.5"x8.13" (with brackets);
weight is 11.16
lbs.
TABLE 14.2-1. Typical Current Drain for Common 21X Peripherals
Typical Current Drain (mA)
Quiescent
Active
Peripheral
RC35 Cassette
PSO-VHF
5
Watt Radio
PSO-UHF 4
Watt Radio
RF95 RF Modem
SM1
9ZSM716 Storage Module
MD9
RAD Modem and
SC932 Interface
DC112 Phone Modem
SDM-AO4
SDM.CD16
SDM-INT8
SDM-SW8A
0
't8
15
1.4
0.25
1.2
2.2
0.002
10.5
6.0
0.4
3
300
1350
1
100
30
3
80
10-15
45
11/LED
lit
6.5
6
T
14-1
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