Rohde amp schwarz ho3500 series logic probe head for hmo oscilloscopes rohde amp schwarz 3594625302 the rohde amp schwarz ho3516 is an active16 channel logic probe head for hmo oscilloscopes this logic probe is not coupled to a specific instrument and can be used with all ramps hmo oscilloscopes rohde amp schwarz ho3516 16 channel logic probe head for hmo oscilloscopes