I want a signal generator for high quality FM tuner alignment. I know the Sound Technology units are supposed to be common, but I never see any come up for sale. I don't do much RF, but have an HP3200B, an old Heathkit IG-42, and a Tektronix 191. Can any of these be beaten and coerced into doing the job? Is there some other semi-affordable unit besides the S-T I should look for? Can anyone suggest a diy circuit specific to the purpose? I can build about anything, but I don't want it to become another multi-year project to finish! Thanks 