hello
can anybody tell me the replacement for MRF901 transistor. will Bfr91work?

 

I'll say it's a replacement provided that Vcc stays below 15V.
I checked both the specs, it is not an exact replacement but if you circuit is not too sensitive then you can give it a try.

 

The replacement for the MRF901 in the 317-01 case is NTE64. V CBO - 25V; V CEO - 15V; V EBO - 3V; Ic - 30mA; PD - 375mW; hFE - 80 Typical; Ft - 4.5 GHz Typical; Pg - 10dB at 1GHz; NF - 2.5dB at 1GHz.