Fluke PM6690, Service Manual, Page: 14 / 200

Short Form Specification
Test
Sensitivity and Frequency Range
– Recall the DEFAULT settings.
– Press
INPUT A
.
– Select
50
W
input impedance,
1x
attenuation,
MAN
ual
trigger and Trig ger level 0 V .
– Connect a signal from a HF generator to a BNC power
splitter.
– Connect the power splitter to Input A of your counter
and an oscilloscope.
– Set the input impedance to 50
W
on the oscilloscope.
– Adjust the amplitude according to the following table.
Read the level on the oscilloscope. The timer/counter
should display the correct frequency.
– Connect the signal to Input B.
– Press
INPUT B
.
– Select 50
W
input impedance, 1x attenuation, MAN ual
trigger and
Trig
ger level
0 V
.
– Press
MEAS FUNC
®
Freq
®
Freq A
®
B
– Repeat the measurements above for Input B.
Voltage
– Recall the DEFAULT settings.
– Press
MEAS FUNC
®
Volt
®
Vpp
®
A
– Press
INPUT A
and select
DC
coupling. Do not apply an
input signal to Input A yet.
– Press EXIT/OK .
– The display should now indicate
(disregard the main parameter V
PP
):
V
MIN
= 0 ± 0.015 V and
V
MAX
= 0 ± 0.015 V
– Adjust the current limit of the voltage source to
<200 mA.
– C2.500 V
DC
to Channel A, using the external
low-pass filter on the input.
– The display should now indicate:
V
MIN
= 2.500 ± 0.040 V and
V
MAX
= 2.500 ± 0.040 V
– Repeat the measurement with inverted polarity.
– Press
INPUT A
and select
10x
.
– Press
EXIT/OK
.
CAUTION: Before the next step, make sure
the input impedance is still 1 M
W
. Apply-
ing more than 12 V without proper current
limiting may cause extensive damage to
the main PCB, if the impedance is set to
50
W
.
– Change the DC level to +50.00 V.
– The display should now indicate:
V
MIN
= 50.00 ± 0.65 V and
V
MAX
= 50.00 ± 0.65 V
– Repeat the measurement with inverted polarity.
– Disconnect the DC voltage from Channel A.
– Remove the external low-pass filter.
– Press
INPUT A
and select
1x
.
– Press EXIT/OK .
– Connect a sinusoidal signal to Input A with an amplitude
of 4.000 Vpp and a frequency of 100 kHz.
– The display should now indicate: 4.000 ± 0.150 V
PP
.
– Press
INPUT A
and select
10x
.
– Press
EXIT/OK
.
– Change the amplitude to 18.00 V
PP
.
– The display should now indicate:
18.00 ± 0.84 V
PP
.
– Disconnect the signal from Channel A.
– Press
MEAS FUNC
®
Volt
®
Vpp
®
B
– Press
INPUT B
and select
DC
coupling. Do not apply an
input signal to Input B yet.
– Press
EXIT/OK
.
– The display should now indicate
(disregard the main parameter V
PP
):
V
MIN
= 0 ± 0.015 V and
V
MAX
= 0 ± 0.015 V
– Proceed by repeating the measurements for Input B as
described above for Input A.
Trigger Indicators vs. Trigger Levels
NOTE: This test must be performed in the sequence given.
– Recall the DEFAULT settings.
2-4 Performance Check, Short Form Specification Test
Trigger Level
(manually set)
Trigger Indicator Pass
Input A Input B
+1 V off
-1 V on
0.0 V blinking
Table 2-4
Trigger indicator check.
Frequency
(MHz)
Level Pass/Fail
mV
rms
dBm Input A Input B
10 15 –23
50 15 –23
100 15 –23
200 15 –23
300 25 –19
Table 2-5
Sensitivity for inputs A & B at various frequencies