Warmup
Time
From a cold start (ac power application), the sweep
generator requires approximately 120 hours (5 days)
of warm up to achieve 1 x 10
–7
/day frequency accu-
racy and stability.
If the Option 16 time base is installed, the 681XXA
requires approximately 72 hours (3 days) of warm
up to achieve 5 x 10
–10
/day frequency accuracy and
stability.
When placing the 681XXA in operation from stand-
by, allow 30 minutes warmup to assure stable opera-
tion.
Operating
Environment
The 681XXA can be operated within the following en-
vironmental limits.
Temperature. 0
°
C to 55
°
C (-32
°
F to 131
°
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.
CAUTION
Before installing the 681XXA in its operat-
ing environment, ensure that all airflow
passages at the sides and rear of the in-
strument are clear. This is of particular
importance whenever the instrument is
being rack-mounted.
PREPARATION
INSTALLATION
FOR USE
2-6
681XXA OM
