Special Operating Notes Special Operating Notes - Wavetek 2001 Instruction Manual

OPERATING INSTRUCTIONS
Model 2001
Depress the POWER push-button. The light in the switch
button should light, indicating an operating condition.
(Note: This instrument does not require a warmup period
unless it is t o be used at the extreme limits of its specifica-
tions.)
After completing the set-up, adjust the Model 2001 con-
trols for the required center frequency, sweep width, out-
put amplitude, and sweep rate. Turn the desired markers
on, and adjust their size and width.
3.5 SPECIAL OPERATING NOTES
3.5.1 Errors From Sweep Rate Effects
When sweeping RF circuits having rapid amplitude changes,
errors may occur, due mainly to detector delays. De-
creasing the detector output time constant will minimize
this effect. Figure 3-4 illustrates sweep rate effect.
T R U E
RESPONSE
RESPONSE W l T H
S L I G H T ERROR
DUE T O SWEEP
R A T E BEING
S L I G H T L Y T O O
FAST
RESPONSE W I T H
L A R G E ERROR
D U E T O SWEEP
R A T E BEING
Figure 3-4. Sweep Rate Effects
To check for sweep rate effect, first set the sweep width to
its lowest practical amount, then reduce sweep time while
closely observing the swept output response. Any change
in the response indicates the sweep rate is too fast for a
true response. When a further reduction of sweep time does
not change the response, a true response has been obtained.
3.5.2 Effects From Overloading
The use of excessive signal from the Model 2001 can over-
load the receiver circuits. T o assure that this condition
i s
not present, and that the response is a true representa-
tion o f the device under test, turn the OUTPUT dbm con-
trols t o minimum output amplitude. Gradually increase
the output amplitude until a response is obtained.
Fur-
ther increase of the output amplitude should not change
the configuration of the response envelope except in ampli-
tude. I f the response envelope does change, such a s
flattening at the top, decrease the output just far enough
to restore the proper configuration.
3.5.3 Making Measurements A t Low Levels
When making measurements at low levels, radiation and
ground loops become problems. Using double shielded
cables for cables carrying RF signals helps minimize the
radiation problem. Ground loops causing hum pick-up
can sometimes be eliminated by completing only one
ground connection between each instrument. This applies
particularly to the scope horizontal input. I f the ground
connection is made at the vertical input terminal, an addi-
tional ground at the horizontal input terminal will often
result in hum pick-up.
3.5.4 Operation With Network Analyzers
To operate properly with certain network analyzers several
modifications might be required. Some analyzers require
the removal o f the blanking signal during the sweep return
trace. This can be accomplished by disconnecting the single
wire connected to pin 10 of the M1H Module. Another
modification sometimes required is to provide a horizontal
output ramp that varies from zero t o some positive voltage
instead of the standard -8 t o +8 volt ramp. This can be ac-
complished by connecting a 56 K ohm resistor between
pins 2 and 11 of the M1H Module. This connection pro-
vides a horizontal output signal from approximately 0 t o
11 volts.
3.5.5 Operation With X-Y Plotters
Two features are incorporated into the Model 2001 t o
facilitate operation with X-Y plotters. First,
a
marker clamp
switch that is a part of the Front Panel SIZE Selector
Switch. This marker clamp switch converts the hi-frequency
marker signals to a lower frequency which is compatable
with the operating speed of the plotter pen.
Second is an optional feature (A5). This feature provides
a contact closure during the sweep time to operate the
plotter's pen lift. The A5 feature operates only when the
sweep time selector switch is set to its slowest position, 10
t o 100 sec.
3.5.6 Operation With A n External Monitor
Operation with an external monitor can produce a flatter
OPERATING INSTRUCTIONS
Depress the POWER push-button. The light in the switch
button should light, indicating an operating condition.
(Note: This instrument does not require a warmup period
unless it is to be used at the extreme limits of its specifica-
tions.)
After completing the set-up, adjust the Model 2001 con-
trols for the required center frequency, sweep width, out·
put amplitude, and sweep rate. Turn the desired markers
on, and adjust their size and width.
3.5 SPECIAL OPERATING NOTES
3.5.1 Errors From Sweep Rate Effects
When sweeping RF circuits having rapid amplitude changes,
errors may occur, due mainly to detector delays. De-
creasing the detector output time constant will minimize
this effect. Figure 3-4 illustrates sweep rate effect.
TRUE
RESPONSE
........ 1-------'.....--
RESPONSE WITH
SLIGHT ERROR
DUE TO SWEEP
RATE BEING
SLiGHTL Y TOO
FAST
.......
~----/'--
RESPONSE WITH
LARGE ERROR
DUE TO SWEEP
RATE BEING
FAR TOO FAST
Figure 3-4. Sweep Rate Effects
To check for sweep rate effect, first set the sweep width to
its lowest practical amount, then reduce sweep time while
closely observing the swept output response. Any change
in the response indicates the sweep rate is too fast for a
true response. When a further reduction of sweep time does
not change the response, a true response has been obtained.
3.5.2 Effects From Overloading
The use of excessive signal from the Model 2001 can over-
load the receiver circuits. To assure that this condition
is not present, and that the response is a true representa-
tion of the device under test, turn the OUTPUT dbm con-
trols to minimum output amplitude. Gradually increase
3-6
Model 2001
the output amplitude until a response is obtained. Fur-
ther increase of the output amplitude should not change
the configuration of the response envelope except in ampli-
tude. If the response envelope does change, such as
flattening at the top, decrease the output just far enough
to restore the proper configuration.
3.5.3 Making Measurements At Low Levels
When making measurements at low levels, radiation and
ground loops become problems. Using double shielded
cables for cables carrying RF signals helps minimize the
radiation problem. Ground loops causing hum pick-up
can sometimes be eliminated by completing only one
ground connection between each instrument. This applies
particularly to the scope horizontal input. I f the ground
connection is made at the vertical input terminal, an addi-
tional ground at the horizontal input term ina
I
will often
result in hum pick-up.
3.5.4 Operation With Network Analyzers
To operate properly with certain network analyzers several
modifications might be required. Some analyzers require
the removal of the blanking signal during the sweep return
trace. This can be accomplished by disconnecting the single
wire connected to pin 10 of the M 1 H Module.
Another
modification sometimes required is to provide a horizontal
output ramp that varies from zero to some positive voltage
instead of the standard ·8 to +8 volt ramp. Th is can be ac·
complished by connecting a 56 K ohm resistor between
pins 2 and 11 of the M 1 H Module. Th is connection pro-
vides a horizontal output signal from approximately 0 to
11 volts.
3.5.5 Operation With X- Y Plotters
Two features are incorporated into the Model 2001 to
facil itate operation with X-Y plotters. First, a marker clamp
switch that is a part of the Front Panel SI ZE Selector
Switch. This marker clamp switch converts the hi-frequency
marker signals to a lower frequency which is compatable
with the operating speed of the plotter pen.
Second is an optional feature (A5). This featu re provides
a contact closure during the sweep time to operate the
plotter's pen lift. The A5 feature operates only when the
sweep time selector switch is set to its slowest position, 10
to 100 sec.
3.5.6 Operation With An External Monitor
Operation with an external monitor can produce a flatter