For higher gain, driving loads up to 1 A from TTL or CMOS outputs, you can replace the transistor with a BD135 or BD137. In any case, the transistor must be mounted on a heat sink.

Figure 1 NPN driver for SMA.
For higher gain, driving loads up to 1 A from TTL or CMOS outputs, you can replace the transistor with a BD135 or BD137. In any case, the transistor must be mounted on a heat sink.