Abracon OCXO variable frequency
Notice the spec for "frequency pull range".

Voltage at the control oin is only able to tune the frequency by a few hundred ppb, not by 20% that your application needs.

If you want to use this device type in your application, you'll need to buy one with center frequency of 80 MHz. Then you can use the control pin to compensate for small errors in the oscillator frequency,  not to make gross changes in the frequency.

If you really want a part adjustable between 100 and 80 MHz, you can probably find one. But it will most likely be sold as a VCO (voltage controlled oscillator) rather than an OCXO. And the high adjustment range will come at the expense of higher phase noise and drift due to temperature and aging.