Fluke PM6669 Operator's Manual page 8

Figure 6
Location of the CALIB-Button.
INSTALLATION
CALIB-button
–
Wait about 20 seconds, until the display shows
10.0000000 MHz. Now the oscillator is calibrated.
–
Switch OFF the counter and disconnect the 10 MHz ref-
erence.
Fit the cover.
PM 6669 - OPERATORS MANUAL
Page: 7