Warmup
Time
From a cold start (ac power application), the CW gen-
erator requires approximately 120 hours (5 days) of
warm up to achieve 2 x 10
–8
/day frequency accuracy
and stability.
If the Option 16 time base is installed, the 680XXB
requires approximately 72 hours (3 days) of warm
up to achieve 5 x 10
–10
/day frequency accuracy and
stability.
When placing the 680XXB in operation from stand-
by, allow 30 minutes warmup to assure stable opera-
tion.
Operating
Environment
The 680XXB can be operated within the following en-
vironmental limits.
Temperature. 0
°
C to 50
°
C (-32
°
F to 122
°
F).
Humidity. 5 to 95% relative at 40
°
C.
Altitude. up to 4600 meters (approximately
15,000 feet).
Cooling. Internal cooling is provided by forced
airflow from the fan mounted on the rear panel.
PREPARATION
INSTALLATION
FOR USE
Before installing the 680XXB in its operating environment,
ensure that all airflow passages at the sides and rear of the
instrument are clear. This is of particular importance when-
ever the unit is being rack-mounted.
Keep the cooling fan filter clean so that the ventilation holes
are not obstructed. A blocked fan filter can cause the instru-
ment to overheat and shut down.
CAUTION
2-6
680XXB OM
Summary of Contents for 680 B Series
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