This is a BF199 high frequency NPN transistor, originally made by the likes of Philips. They are more suitable than audio types for use in the radio amplification stages of the circuit. They are now obsolete, but I have stock of them for some years of kit making. BF199 was originally intended as a video amplifier and driver transistor in analogue TV systems. In the next revision of the kit, they will be replaced by the SS9018H, a really nice VHF transistor once made by Fairchild, and other manufacturers in the far East.
A popular myth is that using a VHF transistor in a relatively low frequency radio circuit will give you problems with VHF feedback. I have found the opposite to be the case. Pressing a lower frequency transistor into service for radio stage use will more often give you a problem.