One of the oldest Airfields in Spain!
NDB GE-421 Madrid/Grinon is a navigation aid for Getafe Air Base, a military base 14 kilometers south of Madrid. Established in 1911 Getafe is one of the oldest airfields in Spain. In addition to a logistics squadron from the Spanish Air Force the base hosts Airbus manufacturing facilities where the Eurofighter Typhoon is produced.
I sent my report to informacion@enaire.es and after a reminder got an email reply within a day including the photo of the beacon and the usual Enaire info sheet.