The Baleares class were a group of five frigates built for the Spanish navy in the 1970s. The ships are a modified version of the American Knox class frigates. The key differences are the replacement of the Sea Sparrow PDMS and ASW helicopter facilities by Standard SAM  and associated radars. They received a SPS-52B 3D search radar and one  SPG-51 illuminator for the Standard SM-1 medium range SAM, fired from a  Mk22 16 round single arm launcher. The SQS-26 long range LF sonar was  replaced by a SQS-23G MF sonar, while two Mk25 tubes for Mk37 torpedoes  we mounted in the tramson. The SQS-35 variable depth sonar was  maintained.
The five ships were upgraded several times during their service  lives. They received a Spanish TRITAN combat data system and the EW  suite was upgraded with Spanish equipment. Mk36 SROC decoy launchers  were also added, as well as two quadruple Harpoon launchers amidships.  Two Meroka CIWS  gun system were also fitted. The old SQS-23G sonar was replaced by a  modern DE-1160LF set built in Spain (a larger, lower frequecy version of  the SQS-56 sonar) and the Mk25 tubes were dismounted to allow for  female crewmember berthing.
 The Ships have recently been retired, in order to assume the F-100 frigates costs .
Ships of the class
 F71 Baleares 1970 - 2004
 F72 Andalucia 1971 - 2005
F73 Cataluna 1971 - 2004 
F74 Asturias  1972 - 2009
F75 Extremadura 1972 - 2006 
Andalucia is seen here alongside in Leith
