Tektronix CFG280 User manual

User Manual
CFG280
11 MHz Function Generator
070-8559-03

Copyright Tektronix, Inc. 1991. All rights reserved.
Tektronix products are covered by U.S. and foreign patents, issued and
pending. Information in this publication supercedes that in all previously
published material. Specifications and price change privileges reserved.
Tektronix, Inc., P.O. Box 1000, Wilsonville, OR 97070–1000
TEKTRONIX and TEK are registered trademarks of Tektronix, Inc.

WARRANTY
Tektronix warrants that this product will be free from defects in materials and
workmanship for a period of one (1) year from the date of shipment. If any such product
proves defective during this warranty period, Tektronix, at its option, either will repair the
defective product without charge for parts and labor, or will provide a replacement in
exchange for the defective product.
In order to obtain service under this warranty, Customer must notify Tektronix of the defect
before the expiration of the warranty period and make suitable arrangements for the
performance of service. Customer shall be responsible for packaging and shipping the
defective product to the service center designated by Tektronix, with shipping charges
prepaid. Tektronix shall pay for the return of the product to Customer if the shipment is to
a location within the country in which the Tektronix service center is located. Customer
shall be responsible for paying all shipping charges, duties, taxes, and any other charges for
products returned to any other locations.
This warranty shall not apply to any defect, failure or damage caused by improper use or
improper or inadequate maintenance and care. Tektronix shall not be obligated to furnish
service under this warranty a) to repair damage resulting from attempts by personnel other
than Tektronix representatives to install, repair or service the product; b) to repair damage
resulting from improper use or connection to incompatible equipment; or c) to service a
product that has been modified or integrated with other products when the effect of such
modification or integration increases the time or difficulty of servicing the product.
THIS WARRANTY IS GIVEN BY TEKTRONIX WITH RESPECT TO THIS
PRODUCT IN LIEU OF ANY OTHER WARRANTIES, EXPRESSED OR
IMPLIED. TEKTRONIX AND ITS VENDORS DISCLAIM ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE. TEKTRONIX’ RESPONSIBILITY TO REPAIR OR REPLACE
DEFECTIVE PRODUCTS IS THE SOLE AND EXCLUSIVE REMEDY
PROVIDED TO THE CUSTOMER FOR BREACH OF THIS WARRANTY.
TEKTRONIX AND ITS VENDORS WILL NOT BE LIABLE FOR ANY
INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
IRRESPECTIVE OF WHETHER TEKTRONIX OR THE VENDOR HAS
ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES.

CFG280 User Manual i
Table of Contents
General Safety Summary iii. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Getting Started 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preparing the Function Generator for Use 2. . . . . . . . . . . . . . . . .
Front Panel 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear Panel 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reference 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TTL Signals 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Internal Sweep 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
External Sweep 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Amplitude Modulation 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tone-Burst Generation and
Stepped Frequency Multiplication 13. . . . . . . . . . . . . . . . . . . .
Appendix A: Specifications 17. . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix B: Maintenance 23. . . . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preparing for Shipment 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix C: Replaceable Parts 29. . . . . . . . . . . . . . . . . . . . . . .
Standard Accessories 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Optional Accessories 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table of Contents
ii CFG280 User Manual

CFG280 User Manual iii
General Safety Summary
Review the following safety precautions to avoid injury and prevent
damage to this product or any products connected to it.
Injury Precautions
Use Proper Power Cord
To avoid fire hazard, use only the power cord specified for this
product.
Avoid Electric Overload
To avoid electric shock or fire hazard, do not apply a voltage to a
terminal that is outside the range specified for that terminal.
Ground the Product
This product is grounded through the grounding conductor of the
power cord. To avoid electric shock, the grounding conductor must
be connected to earth ground. Before making connections to the
input or output terminals of the product, ensure that the product is
properly grounded.
Do Not Operate Without Covers
To avoid electric shock or fire hazard, do not operate this product
with covers or panels removed.
Use Proper Fuse
To avoid fire hazard, use only the fuse type and rating specified for
this product.

General Safety Summary
iv CFG280 User Manual
Do Not Operate in Wet/DampConditions
To avoid electric shock, do not operate this product in wet or damp
conditions.
Do Not Operate in Explosive Atmosphere
To avoid injury or fire hazard, do not operate this product in an
explosive atmosphere.
Product Damage Precautions
Use Proper Voltage Setting
Before applying power, ensure that the line selector is in the proper
position for the power source being used.
Provide Proper Ventilation
To prevent product overheating, provide proper ventilation.
Do Not Operate With SuspectedFailures
If you suspect there is damage to this product, have it inspected by
qualified service personnel.
Safety Terms and Symbols
Terms in This Manual
These terms may appear in this manual:
WARNING. Warning statements identify conditions or practices that
could result in injury or loss of life.

General Safety Summary
CFG280 User Manual v
CAUTION. Caution statements identify conditions or practices that
could result in damage to this product or other property.
Terms on the Product
These terms may appear on the product:
DANGER indicates an injury hazard immediately accessible as you
read the marking.
WARNING indicates an injury hazard not immediately accessible as
you read the marking.
CAUTION indicates a hazard to property including the product.
Symbols on the Product
The following symbols may appear on the product:
DANGER
High Voltage ProtectiveGround (Earth)Terminal ATTENTION Referto
Manual
Double
Insulated
Certifications and Compliances
CSA Certified Power Cords
CSA Certification includes the products and power cords appropriate
for use in the North America power network. All other power cords
supplied are approved for the country of use.

General Safety Summary
vi CFG280 User Manual

CFG280 User Manual 1
Getting Started
The Tektronix CFG280 Function Generator produces low distortion
sine waves, square waves, triangle waves, TTL sync signals, positive
and negative pulses, and ramp waveforms in a frequency range of
0.1 Hz to 11 MHz. You can also directly control amplitude and
DC offset.
The sweep function makes the output signal traverse a range of
frequencies. The START and STOP FREQ control settings determine
the sweep rate and sweep width internally or the sweep function can
be input from an external DC signal.
A voltage-controlled frequency (VCF) input controls the output
frequency from an external voltage source. The output frequency can
be swept above or below the selected frequency to a maximum of
100:1, depending on the polarity and amplitude of the VCF input and
the selected output frequency. Provisions are also made for amplitude
modulation of the sine wave output from an external source.
An external gate input allows the generator to operate for the
duration of an externally applied gating signal. This mode provides
either a single cycle output or a train of preselected waveforms,
depending on the gating signal width and the function generator
frequency setting.
The CFG280 Function Generator has a frequency counter to count
the signal frequency of sine, square and triangle waves from 1 Hz to
100 MHz. The frequency counter features one five-digit display with
automatic decimal point placement and LED indicators that show the
display measurement unit and mode. It can measure periods in
seconds or frequencies in kHz or MHz. The front panel controls also
provide selectable gate times (resolution) and selectable X10
attenuation.
The CFG280 has a locking, multiposition handle that folds under the
instrument. The instrument comes with a power cord, an installed
fuse for 115V operation, and this manual.

Getting Started
2CFG280 User Manual
Preparing the Function Generator for Use
Check the following items prior to operating the CFG280 Function
Generator for the first time (see Figure 1 for locations of items 1
through 3):
1
2
3
Figure 1: Line Voltage Selectors, Power Input, and Fuse Locations
CAUTION. To prevent damage to the instrument, set the line voltage
selectors to the proper voltage setting and install the correct line
voltage fuse before operating the equipment.
1. Set the line voltage selectors to the input line voltage. These
selectors connect internal wiring for various line voltages. This
product is intended to operate from a power source that does not
supply more than 250 VRMS between the supply conductors or
between either supply conductor and ground. For line voltage
ranges, refer to Appendix A: Specifications on page 17.

Getting Started
CFG280 User Manual 3
WARNING. To prevent electrical shock, unplug the power cord and
disconnect the signal cable from any signal source before checking
or replacing the fuse.
2. Check that the correct line fuse is installed. The line fuse
provides protection if the equipment malfunctions or an overload
occurs. Refer to Appendix C: Replaceable Parts on page 29 for
fuse part numbers.
WARNING. To prevent electrical shock, connect the power cord to a
properly grounded power source. The outside (ground) of this
connector is connected through the equipment to the power source
ground. Do not remove the ground lug from the power cord for any
reason.
3. Connect the input power cord. Use only the power cords specified
for this equipment. Refer to Appendix C: Replaceable Parts on
page 29 for power cord part numbers.

Getting Started
4CFG280 User Manual
Front Panel
Figure 2 shows the front-panel controls, connectors, and indicators of
the CFG280 Function Generator.
31 2 456 7 89
182022 2123 19
17
16
15
141312
10 11
2425
Figure 2: Front Panel Controls, Connectors, and Indicators
1. OVERRANGE LED.Lights if you apply a frequency above
specified limits to the EXT COUNTER INPUT connector. It also
lights if the gate time is too slow for the incoming signal.
2. GATE LED. Lights when the frequency counter is making a
measurement. The LED will blink when the counter updates the
display.
3. Counter Readout. This is a five-digit display that shows
frequency counter measurements. The decimal point is
automatically placed in the appropriate position, depending on
the measurement and resolution.
4. MULTIPLIER LEDs. Indicate the frequency multiplication factor
of the function generator outputs. The 10-1M LED indicates a
factor from 10 through 106. You should use the 10-1M LED with
the counter readout and FREQUENCY Range LEDs.

Getting Started
CFG280 User Manual 5
The 1 and 0.1 LEDs provide accurate indication for the two
lowest frequency ranges. For example, if the FREQUENCY dial
is set on 2.6 and the 1 LED is lighted, the function generator
output frequency is 2.6 Hz.
5. FREQUENCY Range LEDs. Indicate the range (either MHz or
kHz) of the reading shown on the counter readout. These LEDs
also indicate the frequency range of the function generator
output. For example, if the FREQUENCY dial is set on 9, the
10-1M LED is lighted, the kHz LED is lighted, and the counter
readout shows .090, then the function generator output frequency
is 0.090 kHz = 90 Hz.
NOTE. You must have the SOURCE button set on INT (pushed out) to
differentiate between the 10, 102, 103(kHz),104,105, and 106(MHz)
generator output ranges.
6. SEC LED. Lights when the frequency counter is in PERIOD
mode. The counter readout does not show frequency in hertz, but
period in seconds. For example, if the FREQUENCY dial is set at
4, the 1 multiplier LED is lighted, and the SEC LED is lighted,
the counter readout displays a value close to 0.250. This indicates
the generator output period is .25 s (the frequency is 4 Hz).
7. MULTIPLIER Buttons. Set the frequency range. The left button
raises the range by a power of ten and the right button lowers the
range by a power of ten. For example, if the FREQUENCY dial
is set to 4.7 and the output is set to kHz, when you press the left
multiplier button the output frequency will jump from
4.7 103Hz (4.7 kHz) to 4.7 104Hz (47 kHz).
8. FUNCTION Buttons. Select the type of waveform generated:
sine, triangle, or square.
9. Symmetry Buttons. Select either positive pulse/ramp or negative
pulse/ramp (see Table 1 on page 6). When you push either
button in, the output frequency is 1/10 of the value shown on the
FREQUENCY dial. When you push both buttons in, the output
frequency is 1/19 of the value shown on the FREQUENCY dial.

Getting Started
6CFG280 User Manual
Table
1
: Eff
e
ct of Symm
e
t
r
y Buttons on Output
Wave
fo
r
m L
e
ft Symm
e
t
r
y Button
Ri
ght Symm
e
t
r
y Button
10.SWEEP Button. Activates the internal sweep generator, which
produces a signal that traverses a range of frequencies. This
button enables the SWEEP RATE and SWEEP WIDTH knobs.
You can also feed an external sweep signal into the CFG280
Function Generator through a connector on the rear panel. See
External Sweep on page 11 for further details.
11. SWEEP RATE Knob. Adjusts how often the frequency sweep
reiterates—the rate at which the signal traverses the frequencies.
If you pull this button out, the sweep will stop and you can adjust
the sweep stop frequency with the SWEEP WIDTH knob.
12.GATE SEL Button. Selects the gate time. If the gate time is too
slow for the incoming signal, the OVERRANGE LED lights.
13.ATTN Button. Selects between two levels of input signals for the
EXT COUNTER INPUT. When you push the button in, the
CFG280 Function Generator attenuates the incoming signal by a
factor of ten (the peak-to-peak input level must be between 3 V
and 42V). When you push the button out, the function generator
does not attenuate the input signal (the peak-to-peak input level
must be between 50 mV and 5 V).

Getting Started
CFG280 User Manual 7
14.SOURCE Button. Selects between internal and external counter
input. When you push the button in, the counter readout displays
the signal frequency count from the EXT COUNTER INPUT.
When you push the button out the counter readout displays the
frequency count of the signal being generated by the CFG280
Function Generator.
15.MAIN Button. Selects between two voltage ranges: 0 Vp-p to
2 Vp-p or 0 Vp-p to 20 Vp-p. This control is used with the
AMPLITUDE control to set the voltage level of the MAIN OUT
signal.
16.AMPLITUDE Knob. Adjusts the voltage within the presently
selected range. This control is used with the MAIN control to set
the voltage level of the MAIN OUT signal.
17.DC OFFSET Knob. Sets the DC level (and therefore the polarity)
of the MAIN OUT signal. This knob has no effect until you pull
it out.
18.SWEEP WIDTH Knob. Adjusts the range of frequencies that are
traversed by each sweep.
19.SWEEP OUT BNC. This connector sends sweep signals that you
can adjust with the sweep controls. You can use a sweep signal to
synchronize an external device such as an oscilloscope.
20.MAIN OUT BNC. This connector sends sine, triangle, square,
and positive and negative pulse/ramp signals.
21.SYNC OUT BNC. This connector sends TTL trigger signals.
Amplitude and DC offset adjustments do not affect TTL trigger
output.
22.EXT COUNTER INPUT BNC. This connector can accept
external signals with frequencies between 1 Hz and 100 MHz.
23.FREQ FINE ADJ knob. Allows small adjustments in output
frequency.
24.FREQUENCY Dial. Determines the frequency of the function
generator output, within the range set by the MULTIPLIER
buttons.
25.POWER switch. Toggles instrument power on and off.

Getting Started
8CFG280 User Manual
Rear Panel
In addition to the line voltage switches, fuse, and power cord
receptacle, the items shown in Figure 3 are located on the rear panel.
1
3
2
Figure 3: Rear Panel Connections
CAUTION. To avoid the risk of fire or damage to theCFG280
Function Generator, be sure input equipment is properly grounded
before connecting it to the function generator.
1. GATE INPUT BNC. This connector accepts external gate signals,
which you can use in tone-burst generation. See page 13 for
details.
2. EXT AM INPUT BNC. This connector accepts external
amplitude modulation signals. See page 12 for details.
3. VCF INPUT BNC. This connector accepts external sweep
signals. See page 11 for details.

CFG280 User Manual 9
Reference
This section describes several advanced functions of the CFG280
Function Generator. The variety of swept and modulated signals
available from the function generator make it especially useful for
such applications as testing servo-system or amplifier response,
distortion, and stability. It can be used for FM generation, frequency
multiplication, or as a variable, beat-frequency oscillator. It can be
used to generate repetition rates or tone bursts. The square wave sync
and sweep outputs can be used as a source for TTL logic or to
synchronize an external device,such as an oscilloscope. The CFG280
Function Generator is also useful as a source for amplitude
modulated signals for various purposes.
TTL Signals
To generate a TTL signal, follow these steps:
1. Connect the SYNC OUT connector on the CFG280 Function
Generator to the input BNC connector on an oscilloscope (see
Figure 4) .
Test oscilloscope
CFG280
Figure 4: TTL Signal Test Setup
2. Observe the results on the oscilloscope. If necessary, change the
volts per division setting or other controls on the oscilloscope to
acquire a useful signal.

Reference
10 CFG280 User Manual
3. Change the FREQUENCY range and rotate the FREQUENCY
dial. Observe how the frequency of the TTL signal changes.
4. Rotate the DC OFFSET knob. Notice that this knob has no effect
on TTL signals.
The DC OFFSET knob has no effect because the DC offset of a
TTL signal is standardized for compliance with TTL logic.
Signals produced from the SYNC OUT connector are not affected
by this knob.
5. Rotate the AMPLITUDE knob. Notice that this knob has no
effect on TTL signals.
The AMPLITUDE knob has no effect because the amplitude of a
TTL signal is standardized for compliance with TTL logic.
Internal Sweep
To use the internal sweep function, follow these steps:
1. Connect the MAIN OUT BNC on the CFG280 Function
Generator to the device under test, such as a filter (see Figure 5).
2. Connect the SWEEP OUT connector to one channel of an
oscilloscope (see Figure 5).
Test oscilloscope
CFG280
Device
undertest
MAIN OUT
SWEEPOUT
Figure 5: Internal Sweep Test Setup