document: McDonald, 25, was on the transfer list at Sixfields and has agreed a two-year contract with the Sky Blues.
  He is Coventry's third signing following relegation from League One, after striker Marc McNulty and midfielder Michael Doyle.
  "He is a quick, strong and aggressive centre-half, who can also read the game well," boss Mark Robins said.
  Liverpool-born McDonald started his career at Manchester City's academy before joining the youth set-up at Stoke City.
  He later went on to Oldham, Colwyn Bay, Nantwich, Hereford United and AFC Telford United, joining Northampton in 2015 and making 37 appearances for the Cobblers.
  Find all the latest football transfers on our dedicated page.
summary: Coventry City have signed centre-back Rod McDonald from Northampton for an undisclosed fee.