Hi, everyone. Can anyone point me in the direction of the specifications for Subject instrument. I've just refurbished one that I rescued from thedumpster, but I'm not sure over what frequency range it works - checks out good at 60 Hz, but what about audio frequencies? BTW, it consists of three pieces: 1. a magnetic split-toroidal probe, plus coax cable, 2. an electronics unit that drives a scope on the 50 mV/cm setting, and 3. an old fashioned "wall-wart" p/s (before that term was in vogue!) - all built like a brick outhouse, typical of HP from that era. Cheers, Roger (P.Eng, EE, Canada) PS. I'd appreciate an email to "analogdino 'at' rogers 'dot' com" as I don't get back here often! Many thanks.