  We describe a maximum-likelihood technique for the removal of contaminating
radio sources from interferometric observations of the Sunyaev-Zel'dovich (SZ)
effect. This technique, based on a simultaneous fit for the radio sources and
extended SZ emission, is also compared to techniques previously applied to Ryle
Telescope observations and is found to be robust. The technique is then applied
to new observations of the cluster Abell 611, and a decrement of -540 +/- 125
microJy/beam is found. This is combined with a ROSAT HRI image and a published
ASCA temperature to give an Hubble constant estimate of 52+24-16 km/s/Mpc.
