Too hot, too fast or forever young?

We present the results of a year-long WSRT monitoring campaign for the quasar J 1819+3845. The extreme variations (regularly 10% per minute) axe explained by interstellar scintillation of a source which is no more that 30 microarrseconds in diameter, with a corresponding brightness temperature of similar to 10(13) K.We use the results of this WSRT campaign to infer critical source parameters (size, structure and lifetime). To first order, the changes in the observed scintillation behaviour over the year are interpreted as being due to a peculiar velocity of the scattering plasma (similar to 20 pc distant), and not due to any changes within the source itself. We discus's the source structure on a size of tens of microarcseconds, and illustrate how such a monitoring campaign can yield such, information.