HP 3048A Operating Manual page 174

Table 3-25. Numbered Error Messages (7 of 17)
4
(cont'd)
N
-a
T3
C
o
CD
-
-
-
-
-
-
-
£
\ 1 1 1
n
-
°y>
1 1
T
/ /
1 1
^
'/
1 1
1
7
. , / '
. / '
1 1 1 1 1 1
*—
1 1
1M
100k
10k
1k
100
10
1
.1
Peak Tuning Range (Hz)
* Lag/Lead Filter Number
Figure 3-35. Phase Lock Loop Bandwidth as a Function
of the Peak Tuning Range of the Measurement.
If the modulation bandwidth of the VCO source you are using is not at least 10 times
greater than the PLL bandwidth for the measurement, there are generally three possible
actions you can take.
• Increase the modulation bandwidth of the VCO source. If the VCO source is a bread­
board or prototype oscillator, it may be possible to make the component changes
necessary to provide sufficient modulation bandwidth.
• Use a different VCO source with greater modulation bandwidth.
• Decrease the PLL bandwidth to 1/10 the VCO's modulation bandwidth by decreasing
the Peak Tuning Range (PTR) for the measurement. Use Figure 3-35 to determine
the PTR required. The PTR can be reduced by decreasing the Tuning Voltage Range
value entered. Divide the required PTR by the VCO's Tuning Constant to determine
the appropriate Voltage Tuning Range to enter. (Keep in mind that reducing the PTR
limits the HP 3048A's Frequency Drift Tracking Range for the measurement. For
further information about changing the PTR, refer to Changing the PTR in
Chapter 3 of this manual.)
rev.UJUL88 Signal Source Applications 3-127