Disclosed are compounds of Formula (I) or salts 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 (I) by a carbon ring atom in the heteroaryl and wherein said heteroaryl is substituted with zero to 2 Rb; A is pyrazolyl, imidazolyl, or triazolyl, each substituted with zero or 1 Ra; and R3, Ra, and Rb are define herein. Also disclosed are methods of using such compounds as modulators of IRAK4, and pharmaceutical compositions comprising such compounds. These compounds are useful in treating, preventing, or slowing inflammatory and autoimmune diseases, or in the treatment of cancer.