A compound of Formula or a salt thereof, wherein: HET is a heteroaryl selected from imidazo[1,2-b]pyridazinyl and pyrazolo[1,5-a] pyrimidinyl, wherein said heteroaryl is attached to the pyridinyl group in the compound of Formula by a carbon ring atom in said heteroaryl and wherein said heteroaryl is substituted with zero to 2 R b; A is pyrazolyl, imidazolyl, or triazolyl, each substituted with zero or 1 R a; R 3 is: (i) -CH 2 CH 3, -CH(CH 3) 2, -CH 2 CHF 2, -CH(CH 3)CH 2 OH, oxetanyl, tetrahydropyranyl, or C 3-5 cycloalkyl substituted with zero to 2 F; (ii) pyrazolyl substituted with zero to 2 substituents independently selected from C 1-3 alkyl, C 1-3 hydroxyalkyl, C 1-3 fluoroalkyl, oxetanyl, tetrahydrofuranyl, and tetrahydropyranyl; Ra is: (i) F, Cl, -OH, -CN, C 1-6 alkyl, C 1-4 fluoroalkyl, C 1-4 cyanoalkyl, or C 1-6 hydroxyalkyl; or (ii) C 3-6 cycloalkyl, azetidinyl, oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, piperidinyl, piperazinyl, pyrrolyl, pyrrolidinonyl, morpholinyl, pyrrolidinyl, phenyl, pyrazolyl, imidazolyl, pyridinyl, or pyrimidinyl, each substituted with zero to 4 substituents independently selected F, -CN, -OH, -NR y R y, C 1-3 alkyl, C 1-3 fluoroalkyl, -CH(phenyl) 2, -O(C 1-4 alkyl), -C (C 1-4 alkyl), -C (C 1-4 deuteroalkyl), -C (C 3-6 cycloalkyl), -C O(C 1-4 alkyl), -C NR y R y, - C (phenyl), -C (pyridinyl), -C CH 2 (C 3-6 cycloalkyl), -NHC CH 3, - NHC OCH 3, -NHC OC(CH 3) 3, -S 2 (C 1-3 alkyl), and -OS 2 (C 1-3 alkyl); each R b is independently selected from F, Cl, -CN, -NH 2, -CH 3, -OCH 3, and cyclopropyl; and each R y is independently H or C 1-3 alkyl. HET is a heteroaryl selected from imidazo[1,2-b]pyridazinyl and pyrazolo[1,5-a] pyrimidinyl, wherein said heteroaryl is attached to the pyridinyl group in the compound of Formula by a carbon ring atom in said heteroaryl and wherein said heteroaryl is substituted with zero to 2 R b; A is pyrazolyl, imidazolyl, or triazolyl, each substituted with zero or 1 R a; R 3 is: (i) -CH 2 CH 3, -CH(CH 3) 2, -CH 2 CHF 2, -CH(CH 3)CH 2 OH, oxetanyl, tetrahydropyranyl, or C 3-5 cycloalkyl substituted with zero to 2 F; (ii) pyrazolyl substituted with zero to 2 substituents independently selected from C 1-3 alkyl, C 1-3 hydroxyalkyl, C 1-3 fluoroalkyl, oxetanyl, tetrahydrofuranyl, and tetrahydropyranyl; (i) -CH 2 CH 3, -CH(CH 3) 2, -CH 2 CHF 2, -CH(CH 3)CH 2 OH, oxetanyl, tetrahydropyranyl, or C 3-5 cycloalkyl substituted with zero to 2 F; (ii) pyrazolyl substituted with zero to 2 substituents independently selected from C 1-3 alkyl, C 1-3 hydroxyalkyl, C 1-3 fluoroalkyl, oxetanyl, tetrahydrofuranyl, and tetrahydropyranyl; Ra is: (i) F, Cl, -OH, -CN, C 1-6 alkyl, C 1-4 fluoroalkyl, C 1-4 cyanoalkyl, or C 1-6 hydroxyalkyl; or (ii) C 3-6 cycloalkyl, azetidinyl, oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, piperidinyl, piperazinyl, pyrrolyl, pyrrolidinonyl, morpholinyl, pyrrolidinyl, phenyl, pyrazolyl, imidazolyl, pyridinyl, or pyrimidinyl, each substituted with zero to 4 substituents independently selected F, -CN, -OH, -NR y R y, C 1-3 alkyl, C 1-3 fluoroalkyl, -CH(phenyl) 2, -O(C 1-4 alkyl), -C (C 1-4 alkyl), -C (C 1-4 deuteroalkyl), -C (C 3-6 cycloalkyl), -C O(C 1-4 alkyl), -C NR y R y, - C (phenyl), -C (pyridinyl), -C CH 2 (C 3-6 cycloalkyl), -NHC CH 3, - NHC OCH 3, -NHC OC(CH 3) 3, -S 2 (C 1-3 alkyl), and -OS 2 (C 1-3 alkyl); (i) F, Cl, -OH, -CN, C 1-6 alkyl, C 1-4 fluoroalkyl, C 1-4 cyanoalkyl, or C 1-6 hydroxyalkyl; or (ii) C 3-6 cycloalkyl, azetidinyl, oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, piperidinyl, piperazinyl, pyrrolyl, pyrrolidinonyl, morpholinyl, pyrrolidinyl, phenyl, pyrazolyl, imidazolyl, pyridinyl, or pyrimidinyl, each substituted with zero to 4 substituents independently selected F, -CN, -OH, -NR y R y, C 1-3 alkyl, C 1-3 fluoroalkyl, -CH(phenyl) 2, -O(C 1-4 alkyl), -C (C 1-4 alkyl), -C (C 1-4 deuteroalkyl), -C (C 3-6 cycloalkyl), -C O(C 1-4 alkyl), -C NR y R y, - C (phenyl), -C (pyridinyl), -C CH 2 (C 3-6 cycloalkyl), -NHC CH 3, - NHC OCH 3, -NHC OC(CH 3) 3, -S 2 (C 1-3 alkyl), and -OS 2 (C 1-3 alkyl);