Catalysis of the reaction: 3'-phosphoadenylyl sulfate + [heparan sulfate]-glucosamine = adenosine 3',5'-bisphosphate + [heparan sulfate]-glucosamine 3-sulfate. The [heparan sulfate]-glucosamine 3-sulfate has a substrate consensus sequence of Glc(N2S>NAc)+/-6S GlcA GlcN2S*+/-6S GlcA>IdoA+/-2S Glc(N2S/NAc)+/-6S.