Selection combining (SC) receiver is proposed for fast frequency-hopped binary frequency-shift-keying (FFH/BFSK) communication systems. The bit-error probability is evaluated for the receiver over a frequency-nonselective slowly Nakagami-m fading channel with partial-band noise jamming (PBNJ) and additive white Gaussian noise. It is shown that perfect estimation of the noise power of each hop is required to implement the SC receiver. Furthermore, the SC receiver with high diversity order is immune to PBNJ and it achieves better performance comparing to several other combining receivers when the jamming power is high. An adaptive approach is proposed aiming to improve the performance of SC receiver when the jamming power decreases. It is shown that the improved SC receiver performs well over a wide range of signal to jamming ratio.