hi, i have a circuit diagram of fm transmitter which have a ferriate core inductor but the value given to diameter of ferriate core is not avalible at my place ,so how can replace that ferriate core to an air core , i mean how i can find the same value of that ferriate core by using Air-core inductor

 

Hello,

It is hard to say what value the coil has, as there is no data on the μr of the ferrit core.
Here is a page with some info on the μr :
http://info.ee.surrey.ac.uk/Workshop/advice/coils/mu/index.html#mur

This is a link from the EDUCYPEDIA on Coils

Bertus