  We present results from a first attempt to mitigate radio frequency
interference in real-time during astronomical measurements with a phased array
feed on the 64 m Parkes radio telescope. Suppression of up to 20 dB was
achieved despite errors in estimating the interference spatial signature. Best
results were achieved in the clean excision of a narrowband and stationary
clock signal that originates from the receiver's digital back-end system. We
also contribute a method to interpolate valid beamformer weights at
interference-affected channels. Correct initial beam weights are required to
avoid suppressing the desired signal.
