HP 3314A, Operating Manual

Page: 69 / 114

MODE
(cant)
The approximate bandwidth of the phase locked loop can be determined using this
formula:
B.W. = .2 ( DISPLAYED FREQ )
2N • A
.72
where A = 1 if the EXT REF FREQ is
<
2MHz
A = 5 if the EXT REF FREQ is 2MHz
N = selected N parameter
Note that the 3314A will not update its frequency display unless the loop goes
out of lock (the Fin X N light flashes) and Frequency Range Hold i s OFF .
Fin N
The 3314A output frequency is the reference frequency divided by N. The
reference and 3314A frequency range is limited from 50Hz to 19.99MHz.
Lock acquisition by the 3314A is completely automat ic unless Frequency Range
Hold is asserted. Whenever the reference frequency drifts more than 10%, the
331 4A auto-acquisition re-establishes phase lock. When the Fin N light is
flashing, the 3314A is acquiring phase lock . The acquisition procedure used by
the 3314A is:
-measure the reference frequency.
-display E20 and stop acquisition if the reference frequency is unstable.
- set the 3314A frequency to N times the reference frequency.
-turn the phase locked loop ON and acqu ire lock.
The 3314A will not proceed past the measurement step if the reference frequency
is changing (see Pre-Tuning the 3314A's Oscillator). The 3314A may be able to
acquire phase lock to a changing reference if you try the following:
- w hile in FREE RUN, set the 3314A frequency to the reference frequency
divided by N.
-set Frequency Range Hold ON.
-change the mode to Fin N.
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