Building a flexible setup for parallel transmission (PTx) MRI research is still challenging. A commercial software defined radio device was tested for suitability in a revised setup. Software was developed to make the device generate radiofrequency (RF) bursts in response to triggers. Preliminary bench tests showed quick and reliable triggering, consistent amplitude and phase across channels, and successful runtime adjustment. An initial PTx MRI demonstration showed capability for RF shimming in echo planar imaging of a phantom. Further troubleshooting is planned to reduce observed phase jitter, but the setup is already capable of a range of PTx research applications.