Using isolator to avoid damage to Amplifier.

hi,

Can i use an isolator to avoid reflected power coming back into the power amplifier. There is a chance , when antenna cable is not connected to the amplifier.

yes, that is the main reason they are used. You would need one rated for the power level, since all of the output power will be absorbed by the internal 50 ohm resistor.

Because they are big and expensive, a lot of transmitters just use a dual directional coupler, and shut down the power amp if too big of a load reflection is seen.

I want to get this isolator. Will it work for 50 watts reflected power?

yes it will