Path: utzoo!telecom-request Date: Mon, 6 May 1991 21:41:06 GMT From: Jon Sreekanth Newsgroups: comp.dcom.telecom Subject: 600: 600 ohm Transformer : What Does it Mean? Message-ID: Organization: TELECOM Digest Sender: Telecom@eecs.nwu.edu Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 11, Issue 339, Message 13 of 14 Lines: 28 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