GW Instek GFC-8010H - Manual (Page 10)

FREQUENCY COUNTER
USER MANUAL
17
In actual practice, the worst case conditions described above are almost never
encountered, and furthermore, the high accuracy state is maintained. An example
of rise characteristics given in Fig. 9 and the frequency changes following after the
change of temperature. As shown from the figure, the crystal oscillator of this
instrument reached the thermally balanced state for about 50 minutes after turning
on the switch. This instrument is calibrated about 60 minutes before shipment at
the place of 25℃ ambient temperature.
If measurement is performed more than 1 hour after switching on and an
instrument is calibrated under 20~30 ℃ ambient temperature, 5×10 -6 can be
guaranteed even when the worst crystal oscillator is used.
The 5×10 -6 (25±5℃) represented as a percentage becomes 0.0005%. Aging rate
1×10 -6 /month means that the change after one week under the constant ambient
temperature state, as a percentage of 0.0001%.
FREQUENCY COUNTER
USER MANUAL
18
7.MAINTENENCE
The following instructions are executed by qualified personnel only. To
avoid electrical shock, do not perform any servicing other than the operating
instructions unless you are qualified to do so.
7-1.Standard method for calibration
After 50 minutes warm-up, apply the STD OUT signal of a standard or
high accuracy of 1×10 -7 to the input of the frequency counter. Adjust
Trimmer SVC301 to display value of 10.000000MHz with the standard of
10MHz and the resolution of 1s. An accuracy of over 1×10 -7 can be
obtained through this procedure. Use a screwdriver (not metal tip) to
adjust the trimmer.
7-2.Cleaning
To clean the instrument, use a soft cloth dampened in a solution of mild
detergent and water. Do not spray cleaner directly onto the instrument
because it may leak into the cabinet and cause damage.
Do not use chemicals containing benzine, benzene, toluene, xylene, acetone,
or similar solvents. Do not use abrasive cleaners on any portion of the
instrument.