In the 1996 published text Engineering Electromagnetic Compatibility, by V. Prasad Kodali, IEEE Press Nr PC-4713, the author refers to a similar device for coupling two LISNs for diagnostic purposes; it helps identify CM/DM signals. A simple schematic with resistor values is shown, but details regarding two broadband RF isolation transformers is not supplied. They can likely be arrived at through trial and error, or by exploring a catalog of toroidal RF transformers. The device is called a Paul-Hardin Network in this text. See pages 152 through 154.
I haven't tried making one yet, but as others mentioned it's a good idea to maintain resistor accuracy and symmetry since having a true balance is critical for it's operation as you approach 30 MHz. Regards, Eric Lifsey National Instruments [email protected] (Patrick Lawler) on 12/18/97 06:16:54 PM Please respond to [email protected] (Patrick Lawler) To: [email protected] cc: (bcc: Eric Lifsey/AUS/NIC) Subject: Re: LISN MATE I've been working on a similar test box in my spare time. It takes the two signals from the AC line LISN's, and either adds them together or subtracts them. In the 'add' mode it cancels differential mode signals, leaving only common-mode interference. The 'subtract' mode leaves only differential interference. You can then incorporate the appropriate measures to reduce that particular interfering signal. The box is not used in the official compliance test procedure. It just helps you find solutions. On Tue, 16 Dec 97 09:18:28 MST, [email protected] wrote: > I'm looking for a source for devices known as: > LISN MATE > & > LISN MARK > > They were designed and build years ago by Mark Nave. I understand that > these devices are used as troubleshooting aids to help determine if a > line conducted emission is common mode or differential. > > There may also be schematics of these designs around so someone could > construct there own. > > Does anyone have any information about these devices? > > Thanks, > Brian Kunde > LECO Corp > Compliance Testing Center -- Patrick Lawler [email protected]
