Since there is no typical cct mentioned in the 74S124 datasheet, I implemented the following circuit diagram and observed the output. But there no output shown in the oscilloscope.

What is the wrong with cct? Can anyone help?

 

Connect the enable pin to ground.

Connect some adjustable voltage source to pin 2 and 3 to choose the range and frequency.

See figure 2 of the datasheet.

 

You can look this.

74S124 High Frequency VCO with Varactor

 

You can look this.

74S124 High Frequency VCO with Varactor

Hmm. The particular design needs a high voltage.
I will try the schematic shown above again with the suggestions made by praondevou. Actually I didn't grounded the enable pin.

I think that it is not a problem to give any voltage to pin 2 and 3 to check the free running frequency.
If I am wrong let me know.

 

As praondevou says, 1EN' pin-6 must be tied to GND.
Try 1FC pin-2 at 5V and 1RNG pin-3 at GND.

 

Hmm. The particular design needs a high voltage.
I will try the schematic shown above again with the suggestions made by praondevou. Actually I didn't grounded the enable pin.

I think that it is not a problem to give any voltage to pin 2 and 3 to check the free running frequency.
If I am wrong let me know.

The web that I linked has said:
We can use lower voltage for this, but it means the VCO would be no more wide-range.
So, it depends on how you use the range.