Does vacuum need to be cleaned, as Mr Hoover made a machine for that purpose? Inge -----Ursprungligt meddelande----- Från: Whittaker, Dewey (EHCOE) [mailto:[log in to unmask]] Skickat: den 3 december 2007 15:29 Till: TechNet E-Mail Forum; Hfjord Ämne: RE: [TN] SV: [TN] SV: [TN] SV: [TN] Low Noise Coaxial Cable Question If you fill something with a vacuum, how do you know when it's full? If you fill something in a vacuum, the evacuation process will mean there was no one around to see it, so is it really filled? How do you get all those Hoovers, Kenmores and Dysons in the cables to begin with? Dewey -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Hfjord Sent: Friday, November 30, 2007 2:19 PM To: [log in to unmask] Subject: [TN] SV: [TN] SV: [TN] SV: [TN] Low Noise Coaxial Cable Question We use vacuum 'filled' cables, or rather flexible metal tubes, for obtaining best possible S/N ratio. I'll check with the guys if these 'cables' are suitable for your purpose. However, they cost a lot, typically 1,000 USD/meter. I'll also check what kind of cable there is for my own Keithley pico ampere meter. I noted in their manual, the importance of having as short as possible cable, constant room environment, and that the job is more about calibrating than measuring. One of my friends is a SIR specialist. I'll check if he has something to add. Another is professor on a uni with dielectricum as specialty. (he never understands my questions despite his grade..or I'm too stupid to understand his replies) /Inge -----Ursprungligt meddelande----- Från: TechNet [mailto:[log in to unmask]] För Joe Russeau Skickat: den 30 november 2007 20:41 Till: [log in to unmask] Ämne: Re: [TN] SV: [TN] SV: [TN] Low Noise Coaxial Cable Question Doug, You quote Joe just fine. I should've been a little more detailed in my original posting. I automatically assumed that it would boil down to the materials making up low noise coaxial cable as opposed to standard coaxial cable. Silly me, I should have known better. As always, I appreciate your inputs and those of the other TechNet Gurus. Joe Russeau ----- Original Message ----- From: "Douglas O. Pauls" <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, November 30, 2007 2:28 PM Subject: Re: [TN] SV: [TN] SV: [TN] Low Noise Coaxial Cable Question Obviously Joe quotes Joe better than I quote Joe. So, yeah, what he said.......... Man, am I glad it is Friday......... Doug Pauls Joe Russeau <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 11/30/2007 01:22 PM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to Joe Russeau <[log in to unmask]> To [log in to unmask] cc Subject Re: [TN] SV: [TN] SV: [TN] Low Noise Coaxial Cable Question Hello Seth and Inge, Seth thank you for that very educational response. Basically, I am researching all of the different SIR test equipment available. I'm looking into purchasing a newer system (By-the way, this is not an invite to SIR equipment manufacturers to bombard me with product literature). Anyway, one of the groups I have been speaking with recommended using their low noise coaxial cables. I asked how they classified the cable as low-noise. They responded that they pull the cable taught, drop a weight on it and measure the resulting charge. If no charge, then it is considered low noise. What I had hoped for with asking my question and the question to TechNet, was to find out what materials were best for low-noise coaxial cables. I have been contacting different cable manufacturers, who claim to have low-noise cable, to try and determine if the materials sets are consistent from manufacturer to the next. I figured that would allow me to find the cabling and perhaps make the cables myself. What I have found is that each cable manufacturer uses different materials for their low-noise cable. So, now I'm back to square one. So perhaps I should ask the question this way. If you were in the process of measuring low currents, as is done in an SIR test, and you were looking into coaxial cables as the transfer vehicle from the DUT to the measurement equipment, what materials would you prefer in the cables to give the best data integrity? Best Regards, Joe Russeau ----- Original Message ----- From: "Hfjord" <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, November 30, 2007 1:27 PM Subject: [TN] SV: [TN] SV: [TN] Low Noise Coaxial Cable Question Exellent! However, Joe has still not told us WHAT he wants to do with the cable. I doubt he is on a level, that dielectric intrinsic noise will play a role. Few test engineers work with such problems. If he isn't a Nobel Prize aspirant of some kind. I suggest someone finds remedy against Tinnitus. He/she will get the prize, I'm sure. And the inventor will create a lot of noise...he-he /Inge -----Ursprungligt meddelande----- Från: TechNet [mailto:[log in to unmask]] För Seth Goodman Skickat: den 30 november 2007 18:55 Till: [log in to unmask] Ämne: Re: [TN] SV: [TN] Low Noise Coaxial Cable Question Joe, Some of what has been mentioned is really part of other cable specifications and has nothing to do with noise created in the cable itself. For instance, penetration of electromagnetic fields inside a cable shield is often described by the manufacturer's specification for shielding effectiveness. To the extent that the cable has in imperfect coaxial shield, it can convert ambient electric or magnetic fields into a loop voltage or flowing current. If external fields are the source of your problem, you want cable with high shielding effectiveness as opposed to low-noise cable. For electric fields, improving the shield means thicker braid, finer wire in the braid, better conductivity of braid wire and plating, more than one braid and/or a foil shield. For magnetic fields, a shielded twisted pair may do better. The traditional electronic noise sources, which are Johnson (thermal) noise, shot noise and a group of unrelated mechanisms that produce 1/f noise, do not produce appreciable noise in cables. When cable manufacturers list a cable as low-noise, they usually mean triboelectric noise. If the connected circuit puts a dc potential on the cable, then mechanical flexing can change the capacitance between conductors, which will cause current to flow in the external circuit. The triboelectric and capacitance change with motion can together be called microphonics, as they are both motion-related. Another source or noise in high-voltage cables is leakage. Regards, Seth Goodman --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY 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