Multifrequency radio observations of 3C 28, 76.1, 186 and 319

Multifrequency observations of 3C 28, 76.1, 186 and 319, made with the One-Mile and 5-km telescopes, enable the spectral-index distributions of each source and the polarization properties of 3C 76.1 to be studied. 3C 28 is shown to have the structure of a Fanaroff-Riley class I source, but it is 10 times more luminous than expected for this class. Although 3C 76.1 is also in Fanaroff-Riley class I, it contains a feature which has the properties of a 'hotspot'. The spectral-index distribution in 3C 76.1 is complex; the magnetic field is perpendicular to the axes of the jets, and the polarization properties are consistent with a tangled-field model. The morphology of 3C 186 remains unclear, and 3C 319 is a double source with only one 'hotspot', rather than being a tail source. It is suggested that the different properties of 3C 28 and 76.1 are due to their different environments; this explanation would be consistent with a general scheme which can account for all the observed dependences of source properties on cluster membership. (author)