Philips PM 6670 Operating Manual page 21

23
• Set the pulse width to approx 0.4us and increase
the frequency slowly until the counter starts to display
an incorrect pulse width.
• Push SLOPE for input A and release SLOPE for
input B. The dead-time should be less than O.Sps.
• Release COM via A and SLOPE for input A.
Check of FREQUENCY AVERAGE
• Select FREQ A.
• Set slide switch E on the rear panel to position
FREQ AVERAGE.
•Connect a 120MHz sine-wave with 50mVpp ampli
tude to input A.
• Set the measuring time to Is. The display read-out
should be 120.XXXXX MHz.
• Connect the signal below to input E.
"""L
5/us
JOO/jS
— OV
Remove the signal form input E and set the slide
switch to position EXT RESET.
Check of EXTSTDIN
• Select FREQ A and push CHECK.
• Set the slide switch for connector D on the rear
panel to position EXT STD IN.
• Connect a 10MHz, IVpp sine-wave via a 50ohm
termination and a BNC T-piece to connector D.
• Measure the amplitude with a lOMohm probe via
the T-piece.
• Check that the Gate indicator LED blinks and that
the display read-out is 10.0000MHz at a measuring
time of 10ms.
• Set the frequency to 10kHz.
• Check that the Gate indicator LED blinks and that
the display read-out is 0.0100MHz.
• Reset the slide switch to INT STD OUT.
Check Of INT STD OUT
• Connect an oscilloscope via a 10Mohm probe
the INT STD OUT connector on the rear panel.
• Voltage levels are illustrated below.
to
'The display read-out should be 120.XXX MHz.
' Note that the result now is approx 0.2% higher.
' Reset slide switch E to EXT RESET.
Please refer to Section, Theory of Measurements
for more information about frequency average
measurements.
Check of EXT RESET and ARMING
(PM 6671 and PM 6672)
• Select PERIOD A.
• Set the measuring time to 1 .Os.
• Connect a DC voltage of +0.5V to input E and
check that the counter is not reset; apply + 1.0V
and check that the counter resets.
• Push DISPL HOLD.
• Connect single-shot, positive pulses with + 1.5V
amplitude and 1 80ps duration to input E.
• Check that the counter makes a measurement for
each single-shot.
• Release DISPL HOLD.
• Set the slide switch to position ARMING.
• A DC voltage of + 0.5V connected to input E should
not arm the counter, but + 1.5V should (the GATE
LED stops blinking).
• Single- shot pulses, as illustrated below, should make
the GATE LED blink for each pulse.
4 OOns
f.5[/
— ?9V
Check of GATE MONITOR
(PM 6671 and PM 6672)
• Connect an oscilloscope to the GATE MONITOR
output on the rear panel.
• Check that the signal is correct. As it is difficult
to get a steady display on an oscilloscope, only a
schematic illustration of the display is given.
PM 66 72 :
PM 66 7t •
>3.5V
> 2.0 V
< 0. 4 1/ < O.PV
JOms
10ms