Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!uunet!world!jon_sree From: jon_sree@world.std.com (Jon Sreekanth) Newsgroups: sci.electronics Subject: 600: 600 ohm transformer : what does it mean ? Message-ID: Date: 6 May 91 21:35:48 GMT Sender: jon_sree@world.std.com (Jon Sreekanth) Distribution: sci Organization: The World Lines: 29 Posted to comp.dcom.telecom, sci.electronics This is probably a simple question : what is the meaning of a spec such as a transformer being 600 ohm : 600 ohm ? For example, some telecom transformers (phone line interface transformers) are spec'ed this way. My understanding is if a transformer is ideal, it reflects the secondary impedance to the primary. So, if a transformer primary is connected to the telephone line, and the secondary is left open circuited, the AC impedance that the telephone line sees is infinity, right ? If the secondary is shorted, the telephone line should see an AC short; if the secondary is connected to a 600 ohm load, the telephone line should see 600 ohm. In summary, what does the magic 600:600 spec mean ? Any 1:1 transformer should be interchangeable, and line matching really means the secondary should be terminated into the proper impedance. What am I missing ? Thanks, / Jon Sreekanth Assabet Valley Microsystems Fax and PC products 346 Lincoln St #722, Marlboro, MA 01752 508-562-0722 jon_sree@world.std.com