Please someone explain to me what is H1 to H4 in the following schematic
thanks

http://fmuser.org/news/fm-transmitter/make-the-5W-FM-transmitter.html

 

Chokes, but not specified anywhere in the text.

 

Chokes, but not specified anywhere in the text.

OK, any idea? What sort of chokes is good for this one?

 

No, I could not guess. The ones marked L are critical and no specs for those either. The schematic us useless without them.

 

The circuit is missing the pre-emphasis audio equalization that all FM radio stations use, and that all FM radios have that convert sounds back to normal.
Then sounds on an FM radio will be muffled with attenuated high audio frequencies, allowing you to hear the RF cops coming to arrest you for transmitting and interfering without a license.