If you are running the standard Husky electrical system, it is probably AC. My old 390 motoplat system would not run an AC horn. I guess the generating system was feeling it's age. AC horns take a great deal more current to run than a DC one. If you put a DC horn on an AC system it will probably not work, and vise versa.
I fitted a new Electrex World ignition and lighting coils a while back. The system was wired as AC and the new AC horn would not work.
Long story short, I now run a Power Dynamo (MZB) system as a DC, and the horn (using a new DC horn) and lights are great.
I've got one on both of my Husky's and rate them highly.
Are you running the SEM generating unit ?? You could try a voltage regulator/rectifier to create a DC current to your lights and horn.
