He worked at Radio London and Radio Luxembourg before becoming one of the first DJs on BBC Radio 1 - alongside Tony Blackburn and John Peel.
For the last 17 years he presented vintage chart and country music programmes on BBC Radio Kent and other BBC radio stations in the South.
Paying tribute, Tony Blackburn said: "He was a very, very nice guy. His shows were very entertaining and as a person he was very warm, very good company to be with. I enjoyed his company immensely."
Another former BBC Radio 1 DJ, David Hamilton, said: "I always found him very easygoing company. We'd enjoy a drink and a laugh together.
"When we got together there was loads of laughter. I just remember him as great fun."
Friends, colleagues and fans have also paid tribute on Twitter.
He leaves a wife, Sara, who he met while working at BBC Radio Kent.
Timeline: A legendary career
1964 - Cash is a pirate radio DJ when off-shore Radio London sets sail
1967 - BBC Radio 1 is launched with Cash as a founding DJ, alongside the likes of Tony Blackburn, Alan 'Fluff' Freeman and Pete Murray
1973 - He is hired as production director and presenter at fledgling Capital Radio where he was reunited with his former pirate radio partner Kenny Everett, reviving their popular and anarchic Kenny and Cash Show. He spent 21 years at the station.
1999 - Cash joins BBC Radio Kent
2011 - He marries "Emily Email" - colleague Sara Davies - who answers the steady stream of listeners' e-mails and requests