Tektronix CFG280 11 MHz Function generator

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 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.

1 - 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

2 - 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 x 10³ Hz (4.7 kHz) to 4.7 x 10⁴ Hz (47 kHz)

3 - Function Buttons. Select the type of waveform generated: sine, triangle, or square

4 - 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

5 - 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 Widht knobs. You can also feed an external sweep signal into the CFG280 Function Generator through a connector on the rear panel. 

6 - Gate Sel Button. Selects the gate time. If the gate time is too slow for the incoming signal, the Overrange Led lights

7 - Attn Button. Selects between two levels of input signals for the Ext Counter Input When you push the button in, the CFG280 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)

8 - 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

9 - Main Button. Selects between two voltage ranges: 0 V_p-p to 2 V_p-p or 0 V_p-p to 20 Vp-p. This control is used with the Amplitude control to set the voltage level of the Main Out signal

10 - 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

11 - 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

12 - Sweep Width Knob. Adjusts the range of frequencies that are traversed by each sweep

13 - Frequency Dial. Determines the frequency of the function generator output, within the range set by the Multiplier buttons

14 - Frequency Fine Adj knob. Allows small adjustments in output frequency

15 - Ext. Counter Input BNC.  This connector can accept external signals with frequencies between 1 Hz and 100 MHz

16 - Sync Out BNC. This connector sends TTL trigger signals Amplitude and DC offset adjustments do not affect TTL trigger output

17 - Main Out BNC. This connector sends sine, triangle, square, and positive and negative pulse/ramp signals

18 - 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

19 - Sweep Width knob. Adjusts the range of frequencies that are traversed by each sweep

Rear Panel

1 - VFC Input BNC. This connector accepts external sweep signals

2 - GATE Input BNC. This connector accepts external gate signals, which you can use in tone-burst generation

3 - EXT AM Input BNC. This connector accepts external amplitude modulation signals

Tektronix CFG280 documentation