TEKTRONIX CFG 253 Function Generator

The 9 SWEEP RATE knob only works when scanning internally: adjust the scanning rate (0.5-50 Hz)

Press the 10 SWEEP button → Enable internal sweep frequency; Pop up → Enable external sweep (controlled through VCF INPUT)

Press the SYMMETRY button → Output frequency ÷ 10, and activate the SYMMETRY knob function at the same time; Pop up → Normal frequency, knob failure

Press the 12 VOLTS OUT button → amplitude range 0-2 V ₚₚ (50 Ω load 0-1 V ₚₚ); Pop up → amplitude range 0-20 V ₚₚ (50 Ω load 0-10 V ₚₚ)

13 SYNC (TTL) OUTPUT (BNC interface) outputs TTL synchronization signal with fixed amplitude and DC offset (not affected by AMPLITUDE/DC OFFSET knob)

14 MAIN OUTPUT (BNC interface) outputs sine wave/square wave/sawtooth wave signals, with parameters adjusted by corresponding controls

Press the POWER button to turn on the device; Press again → Shut down

2. Rear panel interface (Figure 3)

Interface Name Function Description

VCF INPUT (BNC) external sweep frequency input interface: Input 0-+10 VDC signal, control the main output frequency sweep (range of 2 times ten)

Core Function Operation Guide

1. TTL signal generation

The TTL signal parameters (amplitude, DC offset) comply with the TTL standard and cannot be adjusted. The operation steps are as follows:

Connect the oscilloscope input to the SYNC (TTL) OUTPUT interface of CFG 253 using a BNC cable;

Press the POWER button to turn on the device, use the RANGE button to select the frequency range, and rotate the FREQUEncy knob to fine tune the frequency;

Observe oscilloscope waveform: Rotate the DC OFFSET or AMPLITUDE knob, and the waveform remains unchanged (TTL signal parameters are fixed).

2. External frequency scanning operation

External frequency scanning requires controlling the scanning parameters through an external voltage source. The steps are as follows:

Connect the MAIN OUTPUT of CFG253 to the oscilloscope input using a BNC cable, and connect the external voltage source to the VCF INPUT (rear panel) of CFG253 using a BNC cable;

Rotate the SWITCHY knob to the "0.3" position (ensuring that the sweep range covers the required area);

Pop up SWEEP button (turn off internal sweep and enable external control);

Adjust the output of the external voltage source (0-+10 VDC), and observe the frequency change of the main output with an oscilloscope: voltage increase → frequency decrease, voltage decrease → frequency increase, with a sweep frequency range of 2 harmonics (100:1).

3. Adjustment of waveform symmetry

Symmetry adjustment can change the "asymmetry degree" of the waveform, which only takes effect when the SYMMETRY button is pressed. The steps are as follows:

Press the Function button to select the target waveform (square wave/sawtooth wave/sine wave);

Press the SYMMETRY button (at this point, the output frequency will automatically ÷ 10, such as the original 100 Hz → 10 Hz);

Rotate the SYMMETRY knob:

Square wave: clockwise → duty cycle increases (high-level time prolongs), counterclockwise → duty cycle decreases (low-level time prolongs), center position → duty cycle 50%;

Sawtooth wave: clockwise → increase rise time, decrease time, counterclockwise opposite;

Sine wave: clockwise → positive half cycle time prolongs, negative half cycle shortens, counterclockwise is the opposite.

Maintenance and Accessories

1. Daily maintenance

Cleaning:

After the power is cut off, use a soft cloth dipped in a mixture of "mild detergent+water" to wipe the surface of the equipment;

It is prohibited to directly spray cleaning agents onto the equipment (which may seep into the interior and damage the circuit);

Do not use solvents or abrasives containing benzene, toluene, acetone, or xylene (which can corrode the casing/scratch the panel).

Transport packaging:

If there is no original packaging, choose corrugated cardboard boxes with internal dimensions at least 3 inches larger than the equipment;

Put the equipment into a plastic bag (to prevent moisture and loose fillers from entering);

Fix the equipment with foam, bubble film and other materials to avoid shaking during transportation;

Seal the cardboard box with packing tape to ensure firmness.

Troubleshooting:

Problem: After pressing the POWER button, the POWER On Light does not light up;

Troubleshooting: After power failure, disconnect all signal cables, open the fuse cover to check if the fuse is blown. If it is blown, replace it with a new fuse of the corresponding specification (refer to the fuse specifications in the "Safety Regulations").

2. Accessories List

(1) Standard accessories (shipped with equipment)

Accessory Name Tektronix Part Number Applicable Scenarios

3AG fuse (0.3 A, 250 V) 159-0029-00 90-132 VAC power environment

115 V power cord reference table 7 North American 115 V power supply

CFG 253 User Manual 070-8362-XX Equipment Operation and Maintenance Guide

(2) Optional accessories (additional order required)

Accessory Name Tektronix Part Number Applicable Scenarios

3AG fuse (0.15 A, 250 V) 159-0054-00 198-250 VAC power environment

230 V power cord (regional adaptation) reference table 7: Europe, UK, Australia and other 230 V regions

(3) Regional compatible power cord specifications (Table 7)