HP 3335A - Sweep and Manual Frequency Control; Manual Frequency Tuning; Sweep Mode Operation Modes

Model 3335A
DATA ENTRY Keys. Used to finalize. the sweep width
entry.
DISPLAY INDICATORS:
SWEEP WIDTH Indicator. Indicates the front panel is dis-
playing the present sweep width or a sweep width entry.
ENTRY Indicator. Indicates the display holds a sweep
width entry not yet finalized by a data entry key.
The numeric display indicates the sweep width program-
med.
Example:
Program a sweep width of 580.34 kHz
Display Result: 580.34 kHz.
3-49. Manual Frequency Tune.
3-50, The frequency can be manually altered in the manual
tune mode. The frequency change is controlled by a front
panel frequency knob. The 3335A can be put in the manual
tune mode by the MANUAL TUNE ON/OFF key. When
the manual tune key is activated, an annunciator above the
key is illuminated.
3-51. In addition to the ON/OFF key, the MANUAL
TUNE controls include two digit keys, a left arrow and a
right arrow. These keys are used to select the sensitivity of
the manual tune knob. When the manual tune mode is
first activated, the fourth digit from the right flashes. The
frequency can be changed: with the sensitivity of the
flashing digit by turning the frequency knob. For more or
less sensitivity, the flashing digit can be moved using the
left and right digit arrows. Holding an arrow key down
causes the flashing digit to step successively to the end.
digit. When in the MANUAL TUNE mode, the frequency
can be incremented by the frequency increment using the
INCR keys and all operating parameters can be checked
using the FUNCTION keys. A description of the MANUAL
TUNE controls follows.
KEYS:
MANUAL TUNE ON/OFF. This key activates the manual
tune mode. When on, an annunciator above the key is
illuminated.
LEFT ARROW Digit Key. Steps flashing digit to the left.
RIGHT ARROW Digit Key. Steps flashing digit to the right.
Frequency manual tune knob. Used to change the fre-
quency with the sensitivity of the flashing digit.
3-52. Sweep Mode.
3-53. The sweep mode can be used to sweep the output
frequency over a specified center frequency. This mode of
operation is controlled by the FREQUENCY SWEEP keys
which include GO TO START FREQ, START SINGLE
10 SEC, START SINGLE 50 SEC, MANUAL, START
AUTO and STOP. A SWEEP OUTPUT connector below the
Section IH
keys provides an output proportional to the sweep fre-
quency for use with a plotter. The frequencies of a fre-
quency sweep are determined by the sweep width and
center frequency. The sweep rate in AUTO is approxi-
mately 8 sweeps/second, 100 steps/sweep. In MANUAL,
10 SEC and 50 SEC sweeps, the sweep contains 1000 steps.
NOTE
Whenever the -hp- 3335 sweeps through either
20 MHz or 40 MHz, the amplitude of the
output will drop severely for approximately 5
msec. Other, much less drastic amplitude
discontinuities may be observed. When the
instrument sweeps through 10 MHz, 14 MHz,
28 MHz and 56 MHz.
KEYS:
GO TO START FREQ Key. This key is used to display and
output the starting frequency of the sweep. The starting
frequency is determined by the center frequency and the
sweep width. Half the sweep, determined by the sweep
width, is below the center frequency establishing the start
frequency.
START SINGLE 10 SEC Key. This key is used to initiate
a single sweep beginning at the start frequency below the
center frequency. The time for the sweep to go from start
to finish is approximately 10 seconds and consists of 1000
steps. When the sweep is in this mode, an annunciator
above the key is illuminated: The sweep rate can be
changed during the sweep by pressing the 50 SEC key or
can be stopped by pressing the STOP key. Pressing the
AUTO key will put the sweep into auto sweep. During any
sweep, depressing a key outside the frequency sweep
group has no effect on operation.
START SINGLE 50 SEC Key. This key is used to initiate
a single sweep which requires approximately 50 seconds to
complete and consists of 1000 steps.
START AUTO Key. This key is used to initiate the sweep
which sweeps continuously from the start frequency to the
upper limit. The sweep resets to the start frequency when
the upper limit is reached and again sweeps up in frequency
at a rate of approximately 8 sweeps/second and 100 steps/
sweep. The frequency is only swept in the increasing fre-
quency direction in both the single sweep or auto sweep
modes. When the instrument is in the auto sweep mode, the
display is blank except for the SWEEPING annunciator.
The STOP key must be used to exit an auto sweep.
MANUAL key. This key is used to put the sweep into a
manual sweep mode. When activated, an annunciator is
illuminated to the left of the MANUAL key. The frequency
sweep between the start frequency and upper limit can be
manually controlled by the frequency knob making 1000
steps between the two limits. When either the upper limit
or start frequency is reached, the manual sweep stops.
When the frequency knob is rotated changing the fre-
quency, the display segments and annunciators may dim
slightly.
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