Not a Soviet mission, but Magellan, built by Hughes Space & Communications Group in the 1980s, did an extensive survey of the surface of Venus using RADAR.
Edit: The Wikipedia page says; "The spacecraft was designed and built by the Martin Marietta Company,[5] and the Jet Propulsion Laboratory (JPL) managed the mission for NASA." It has no mention of Hughes other than partial credit under "Manufacturer".
https://en.wikipedia.org/wiki/Magellan_(spacecraft)
Hughes built the Synthetic Aperture RADAR payload.
https://solarsystem.nasa.gov/missions/magellan/in-depth/
Edit: The Wikipedia page says; "The spacecraft was designed and built by the Martin Marietta Company,[5] and the Jet Propulsion Laboratory (JPL) managed the mission for NASA." It has no mention of Hughes other than partial credit under "Manufacturer". https://en.wikipedia.org/wiki/Magellan_(spacecraft)
Hughes built the Synthetic Aperture RADAR payload.