Re: [SI-LIST] : Re: Diff probes for tdr.

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From: Bob Lewandowski (Bob.Lewandowski@Vixel.com)
Date: Fri Oct 20 2000 - 12:18:19 PDT


I'd be real cautious about not tying down grounds and relying on the power
cord/chassis interconnects to eliminate common mode signals between the scope common
and the DUT power supply common. TDR/sampling heads are DC coupled, and can easily be
overwhelmed by even a low frequency signal that exceeds their common mode range, or
upsets the sampling head bias. The ground between differential signals is only
"virtual".

---Bob Lewandowski

Ron Miller wrote:

> Good comments Bob
>
> If you are measuring a differential line, though, you do not
> have to connect the ground. All you are really intrested in
> is the differential impedance. The impedance to ground is
> irrelevant, because you have a virtual ground half way between
> the two differential drive pins anyway.
>
> Ron Miller
>
> > -----Original Message-----
> > From: Bob Lewandowski
> > Sent: Thursday, October 19, 2000 7:04 PM
> > To: Ken Taylor
> > Cc: si-list@silab.eng.sun.com
> > Subject: Re: [SI-LIST] : Re: Diff probes for tdr.
> >
> > I concur with all the semi-rigid coax comments. Most all of the commercial
> > probes I've seen generate large launch discontinuities (~20%), with the
> > exception of Picoprobe, and Cascade Microtech (both $$$ !).
> >
> > I've used .047" diameter coax, either solid jacket or the tin dipped braid type
> > (very flexible). Tensolite/QMI sell .047 cable assemblies of the braid type
> > with male or female SMAs, that they call Semi-Flex. Just buy a 1 ft. cable and
> > chop it in half, match the lengths for differential. With the small coax you
> > can solder the jacket to a board ground next to a trace, and with a very short
> > center conductor, keep the launch reflection down to around 5%. Semi-rigid coax
> > typically can be obtained with tight tolerance on the Z0, so the cable becomes a
> > good reference impedance before the launch. Be cautious about minimizing the
> > length, as the small stuff is pretty lossy and degrades rise time.
> >
> > ---Bob Lewandowski
> > Vixel Corp.
> >
> > Ken Taylor wrote:
> >
> > > John Fisher's solution below is a very good one that I have used
> > > extensively. Although a little clumsy mechanically (you will want to use a
> > > probe positioner, hold the probe at about 45 degrees to get the tips and the
> > > ground to contact, keep the tips and ground path VERY short like 2 mm or so)
> > > they give great results. One more thing, however: If the probe impedance
> > > doesn't match your DUT impedance, you will get reflections etc. and you
> > > won't be able to see anything close in to the contact point. To solve that,
> > > match the impedances as closely as possible, keep the probe (semi rigid
> > > stuff) more than, say, 6" long, and then all the mismatch will be at the
> > > flexible cable/probe connection, and you can keep it out of the way of your
> > > measurements. These probes work well for 17 pS Tr.
> > > One last thing, these things were whipped up for customers by friendly Tek
> > > AEs, and weren't part numbered for sale. (How can you charge $5000 for these
> > > things? Can't, so they don't sell them!) The real Tek (and Agilent) probes
> > > looked nice, are definitely nicer mechanically, but can't hold a light to
> > > these "do it yourself" probes.
> > >
> > > Regards, Ken.
> > >
> > > Ken Taylor
> > > Polar Instruments, Portland, OR, USA.
> > > ken.taylor@polarinstruments.com
> > >
> > > John said
> > > <<We have built these using equal length sections of semi rigid coax with
> > > sma's at one end. The semi rigid copper outer shield is soldered together
> > > approx. every 3 &quot;.&nbsp; Prepare the ends by careful cutting of the
> > > shield with an exacto knife,&nbsp; than solder the center conductors to
> > > the launch point vias or pads. Tektronix shipped some of&nbsp; these to
> > > us as accessories when we bought their IPA-510 a few years ago.&nbsp; I
> > > might be able to find a tek part number but someone like Micro-Coax could
> > > make some for you or find an off the shelf semi rigid assembly with sma's
> > > on both ends and then just cut it in half. Be carful not to bend it too
> > > much and kink it.&nbsp; These can also make nice 50 Ohm 10x passive
> > > probes with the addition of a series 450 resistor at the end.<br> >>
> > >
> > > ----- Original Message -----
> > > From: "si-list-digest" <owner-si-list@silab.eng.sun.com>
> > > To: <si-list-digest@silab.eng.sun.com>
> > > Sent: Thursday, October 19, 2000 5:00 PM
> > > Subject: si-list-digest V1 #286>
> > >
> > > >
> > > > si-list-digest Thursday, October 19 2000 Volume 01 : Number
> > > 286
> > > >
> > > >
> > > >
> > > > In this issue:
> > > >
> > > > 1.) [SI-LIST] : High Frequency Seminar
> > > > "chasgra" <chasgra@email.msn.com>
> > > >
> > > > 2.) [SI-LIST] : SI - Salary Survey
> > > > sainath nimmagadda <nescafe@dacafe.com>
> > > >
> > > > 3.) [SI-LIST] : Differential TDR probes
> > > > "zanella, fabrizio" <zanella_fabrizio@emc.com>
> > > >
> > > > 4.) Re: [SI-LIST] : Differential TDR probes
> > > > "Ritesh Kapahi" <rkapahi@idt.com>
> > > >
> > > > 5.) Re: [SI-LIST] : Differential TDR probes
> > > > Salvador_Aguinaga@3com.com
> > > >
> > > > 6.) RE: [SI-LIST] : Differential TDR probes
> > > > "Daniel, Erik S." <Daniel.Erik@mayo.edu>
> > > >
> > > > 7.) Re: [SI-LIST] : Differential TDR probes
> > > > John Fisher <jmfisher@cisco.com>
> > > >
> > > >
> > > > ----------------------------------------------------------------------
> > > >
> > > > Date: Wed, 18 Oct 2000 18:30:58 -0700
> > > > From: "chasgra" <chasgra@email.msn.com>
> > > > Subject: [SI-LIST] : High Frequency Seminar
> > > >
> > > > This is a multi-part message in MIME format.
> > > >
> > > > - ------=_NextPart_000_000C_01C03931.8EE7A3A0
> > > > Content-Type: text/plain;
> > > > charset="iso-8859-1"
> > > > Content-Transfer-Encoding: quoted-printable
> > > >
> > > > Rocky Mountain Chapter EMC Society presents:
> > > >
> > > > High Frequency Measurements and Noise in Electronic Circuits
> > > > - - one day demonstration based seminar.
> > > >
> > > > An informative and entertaining multimedia seminar for digital and =
> > > > analog designers as well as test engineering and EMC personnel.=20
> > > >
> > > > by Douglas C. Smith=20
> > > >
> > > > Author of High Frequency Measurements and Noise in Electronic Circuits=20
> > > >
> > > > An Unusual Seminar - Sign up here.
> > > >
> > > > This seminar is unique. Demonstrations on real circuits are used to =
> > > > illustrate most of the concepts being taught unlike most seminars which =
> > > > are taught through the use of vu-graphs as the main medium. About 70% of =
> > > > class time is spent in demonstrations. Complicated math is avoided. This =
> > > > format makes the seminar more interesting to the students and helps them =
> > > > to achieve a deeper understanding of the material covered. Many students =
> > > > have said that this was the best technical seminar they ever attended!=20
> > > >
> > > >
> > > >
> > > > When: Dec 1 2000
> > > >
> > > > If you are interested then goto our weblink: =
> > > > http://www.ewh.ieee.org/r5/denver/rockymountainemc
> > > >
> > > > Look for the Dec 1 meeting link and sign up!!
> > > >
> > > > Charles Grasso
> > > > Vice Chair RMCEMCS
> > > >
> > > >
> > > > - ------=_NextPart_000_000C_01C03931.8EE7A3A0
> > > > Content-Type: text/html;
> > > > charset="iso-8859-1"
> > > > Content-Transfer-Encoding: quoted-printable
> > > >
> > > > <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
> > > > <HTML><HEAD>
> > > > <META content=3D"text/html; charset=3Dwindows-1252" =
> > > > http-equiv=3DContent-Type>
> > > > <META content=3D"MSHTML 5.00.2919.6307" name=3DGENERATOR></HEAD>
> > > > <BODY bgColor=3D#ffffff>
> > > > <DIV><FONT size=3D2>
> > > > <P align=3Dcenter><A name=3DTitle><FONT size=3D6>Rocky Mountain Chapter =
> > > > EMC=20
> > > > Society</FONT></A><FONT size=3D6> presents:</FONT></P>
> > > > <P align=3Dcenter><FONT color=3D#0000ff face=3DArial size=3D6><B>High =
> > > > Frequency=20
> > > > Measurements and Noise</B></FONT> <FONT color=3D#0000ff face=3DArial =
> > > > size=3D6><B>in=20
> > > > Electronic Circuits<BR></B></FONT><FONT color=3D#0000ff face=3DArial =
> > > > size=3D5><B>- one=20
> > > > day demonstration based seminar.</B></FONT></P>
> > > > <P align=3Dcenter><FONT size=3D5><I>An informative and </I></FONT><FONT=20
> > > > color=3D#ff0000 size=3D5><B><I><U>entertaining</U></I></B></FONT><FONT =
> > > > size=3D5><I>=20
> > > > multimedia seminar for digital and analog designers as well as test =
> > > > engineering=20
> > > > and EMC personnel.</I></FONT> </P>
> > > > <P align=3Dcenter><FONT face=3DArial size=3D4><B>by </B></FONT><A=20>
> > > > href=3D"http://www.ewh.ieee.org/r5/denver/rockymountainemc/1dayemc.htm#Ab=
> > > > out The Instructor"><FONT=20
> > > > face=3DArial size=3D4><B>Douglas C. Smith</B></FONT></A> </P>
> > > > <P align=3Dcenter><FONT size=3D4>Author of <I>High Frequency =
> > > > Measurements and Noise=20
> > > > in Electronic Circuits</I></FONT> </P>
> > > > <P align=3Dcenter><A=20
> > > > href=3D"http://www.ewh.ieee.org/r5/denver/rockymountainemc/seminarsignup.=
> > > > htm"><FONT=20
> > > > size=3D5><B><U>An Unusual Seminar - Sign up here.</U></B></FONT></A></P>
> > > > <P align=3Dleft>This seminar is unique. Demonstrations on real circuits =
> > > > are used=20
> > > > to illustrate most of the concepts being taught unlike most seminars =
> > > > which are=20
> > > > taught through the use of vu-graphs as the main medium. About 70% of =
> > > > class time=20
> > > > is spent in demonstrations. Complicated math is avoided. This format =
> > > > makes the=20
> > > > seminar more interesting to the students and helps them to achieve a =
> > > > deeper=20
> > > > understanding of the material covered. Many students have said that this =
> > > > was the=20
> > > > <I>best</I> technical seminar they ever attended! </P>
> > > > <P align=3Dleft>&nbsp;</P>
> > > > <P align=3Dleft>When: Dec 1 2000</P>
> > > > <P align=3Dleft>If you are interested then goto our weblink: <A=20
> > > > href=3D"http://www.ewh.ieee.org/r5/denver/rockymountainemc">http://www.ew=
> > > > h.ieee.org/r5/denver/rockymountainemc</A></P>
> > > > <P align=3Dleft>Look for the Dec 1 meeting link and sign up!!</P>
> > > > <P align=3Dleft>Charles Grasso<BR>Vice Chair=20
> > > > RMCEMCS</P></FONT></DIV></BODY></HTML>
> > > >
> > > > - ------=_NextPart_000_000C_01C03931.8EE7A3A0--
> > > >
> > > >
> > > >
> > > > **** To unsubscribe from si-list or si-list-digest: send e-mail to
> > > > majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE
> > > > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
> > > > si-list archives are accessible at http://www.qsl.net/wb6tpu
> > > > ****
> > > >
> > > > ------------------------------
> > > >
> > > > Date: Thu, 19 Oct 2000 11:44:46 -0800
> > > > From: sainath nimmagadda <nescafe@dacafe.com>
> > > > Subject: [SI-LIST] : SI - Salary Survey
> > > >
> > > > Hi SI folks:
> > > >
> > > > I understand that with growing complexity in multimedia technology, SI
> > > > positions are getting increasingly challenging (we see "PhD preferred"
> > > > in ads)and hopefully lucrative too. We often find salary surveys for
> > > > mainstream folks such as IT professionals. I am just curious if there is
> > > > some kind of salary survey for SI folks too. I am sure that helps us SI
> > > > folks have an idea where we stand in this dynamic market.
> > > >
> > > > Best,
> > > >
> > > > SN
> > > > _____________________________________________________________
> > > > Tired of limited space on Yahoo and Hotmail?
> > > > Free 100 Meg email account available at http://www.dacafe.com
> > > >
> > > >
> > > >
> > > > **** To unsubscribe from si-list or si-list-digest: send e-mail to
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> > > > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
> > > > si-list archives are accessible at http://www.qsl.net/wb6tpu
> > > > ****
> > > >
> > > > ------------------------------
> > > >
> > > > Date: Thu, 19 Oct 2000 15:44:15 -0400
> > > > From: "zanella, fabrizio" <zanella_fabrizio@emc.com>
> > > > Subject: [SI-LIST] : Differential TDR probes
> > > >
> > > > We're having problems getting a good high frequency launch when probing pc
> > > > boards and cable differential pairs when taking TDR measurements.Has
> > > anyone
> > > > found good differential TDR probes which allow you to measure very closely
> > > > spaced points on pc boards or cables?
> > > >
> > > > Thanks and regards,
> > > > Fabrizio Zanella
> > > > Hardware Engineering
> > > > EMC Corporation
> > > > fzanella@emc.com
> > > >
> > > >
> > > > **** To unsubscribe from si-list or si-list-digest: send e-mail to>
> > > > majordomo@silab.eng.sun.com. In the BODY of message put: UNSUB> SCRIBE
> > > > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
> > > > si-list archives are accessible at http://www.qsl.net/wb6tpu
> > > > ****
> > > >
> > > > ------------------------------
> > > >
> > > > Date: Thu, 19 Oct 2000 14:12:22 -0700
> > > > From: "Ritesh Kapahi" <rkapahi@idt.com>
> > > > Subject: Re: [SI-LIST] : Differential TDR probes
> > > >
> > > > Agilent has got some micro probe which is an accessory for their high
> > > > bandwidth scope 86100 and differential TDR module 54754A . It usually has
> > > a
> > > > long lead times (3-4 months)
> > > > Bye
> > > > Kaps
> > > >
> > > > - ----- Original Message -----
> > > > From: zanella, fabrizio <zanella_fabrizio@emc.com>
> > > > To: SI List (E-mail) <si-list@silab.eng.sun.com>
> > > > Sent: Thursday, October 19, 2000 12:44 PM
> > > > Subject: [SI-LIST] : Differential TDR probes
> > > >
> > > >
> > > > > We're having problems getting a good high frequency launch when probing
> > > pc
> > > > > boards and cable differential pairs when taking TDR measurements.Has
> > > > anyone
> > > > > found good differential TDR probes which allow you to measure very
> > > closely
> > > > > spaced points on pc boards or cables?
> > > > >
> > > > > Thanks and regards,
> > > > > Fabrizio Zanella
> > > > > Hardware Engineering
> > > > > EMC Corporation
> > > > > fzanella@emc.com
> > > > >
> > > > >
> > > > > **** To unsubscribe from si-list or si-list-digest: send e-mail to
> > > > > majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE
> > > > > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
> > > > > si-list archives are accessible at http://www.qsl.net/wb6tpu
> > > > > ****
> > > > >
> > > > >
> > > >
> > > >
> > > > **** To unsubscribe from si-list or si-list-digest: send e-mail to
> > > > majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE
> > > > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
> > > > si-list archives are accessible at http://www.qsl.net/wb6tpu
> > > > ****
> > > >
> > > > ------------------------------
> > > >
> > > > Date: Thu, 19 Oct 2000 16:39:38 -0500
> > > > From: Salvador_Aguinaga@3com.com
> > > > Subject: Re: [SI-LIST] : Differential TDR probes
> > > >
> > > > Kaps,
> > > >
> > > > Have you comfirmed that the TDR Module 54754A works with their new 86100A
> > > main
> > > > frame?
> > > > They (their sales guys) tell me that it will not be ready until Dec 00.
> > > >
> > > > Thanks,
> > > > - -- Sal
> > > >
> > > >
> > > >
> > > >
> > > > "Ritesh Kapahi" <rkapahi@idt.com> on 10/19/2000 04:12:22 PM
> > > >
> > > > Please respond to "Ritesh Kapahi" <rkapahi@idt.com>
> > > >
> > > > Sent by: "Ritesh Kapahi" <rkapahi@idt.com>
> > > >
> > > >
> > > > To: "zanella, fabrizio" <zanella_fabrizio@emc.com>, "SI List
> > > > cc: (Salvador Aguinaga/MW/US/3Com)
> > > > Subject: Re: [SI-LIST] : Differential TDR probes
> > > >
> > > >
> > > >
> > > > Agilent has got some micro probe which is an accessory for their high
> > > > bandwidth scope 86100 and differential TDR module 54754A . It usually has
> > > a
> > > > long lead times (3-4 months)
> > > > Bye
> > > > Kaps
> > > >
> > > > - ----- Original Message -----
> > > > From: zanella, fabrizio <zanella_fabrizio@emc.com>
> > > > To: SI List (E-mail) <si-list@silab.eng.sun.com>
> > > > Sent: Thursday, October 19, 2000 12:44 PM
> > > > Subject: [SI-LIST] : Differential TDR probes
> > > >
> > > >
> > > > > We're having problems getting a good high frequency launch when probing
> > > pc
> > > > > boards and cable differential pairs when taking TDR measurements.Has
> > > > anyone
> > > > > found good differential TDR probes which allow you to measure very
> > > closely
> > > > > spaced points on pc boards or cables?
> > > > >
> > > > > Thanks and regards,
> > > > > Fabrizio Zanella
> > > > > Hardware Engineering
> > > > > EMC Corporation
> > > > > fzanella@emc.com
> > > > >
> > > > >
> > > > > **** To unsubscribe from si-list or si-list-digest: send e-mail to
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> > > > > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
> > > > > si-list archives are accessible at > http://www.qsl.net/wb6tpu
> > > > > ****
> > > > >
> > > > >
> > > >
> > > >
> > > > **** To unsubscribe from si-list or si-list-digest: send e-mail to
> > > > majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE
> > > > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
> > > > si-list archives are accessible at http://www.qsl.net/wb6tpu
> > > > ****
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > **** To unsubscribe from si-list or si-list-digest: send e-mail to
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> > > >
> > > > ------------------------------
> > > >
> > > > Date: Thu, 19 Oct 2000 17:26:16 -0500
> > > > From: "Daniel, Erik S." <Daniel.Erik@mayo.edu>
> > > > Subject: RE: [SI-LIST] : Differential TDR probes
> > > >
> > > > Fabrizio-
> > > >
> > > > A couple things we have used with some success for diff TDR on PC boards
> > > and
> > > > chip packages:
> > > >
> > > > 1. GGB Picoprobe Model 10
> > > > - --------------------------
> > > > These are micro-coax probes with needle-like tips connected at the end.
> > > > They are pretty cheap, and there are a wide variety of options (different
> > > > needle tip lengths, widths, materials, ...). We have used two
> > > ground-signal
> > > > style probes soldered together to form a GSSG style differential probe.
> > > The
> > > > needles are flexible and can be bent to accommodate different board
> > > > geometries (although bending the needles too much definitely degrades the
> > > > launch). There are some technical drawbacks to these, but they have come
> > > in
> > > > handy for troubleshooting.
> > > >
> > > > 2. GGB Picoprobe Model 40A Dual probes
> > > > - ---------------------------------------
> > > > These are very good microwave probes (with an advertised 40 GHz bandwidth)
> > > > that you can buy in GSSG or GSGSG styles in a variety of pitches. They
> > > are
> > > > fairly expensive, the lead times are long for custom orders, and I would
> > > not
> > > > recommend trying to bend these(!) to accommodate different geometries, but
> > > > they are electrically very good.
> > > >
> > > > There are a number of other similar microwave probes we have used in
> > > various
> > > > special cases, but I think I have used these two options the most.
> > > >
> > > > - Erik
> > > >
> > > > ==================================================================
> > > > Erik Daniel, Ph.D. Mayo Foundation
> > > > Voice: (507) 284-1634 Guggenheim 1011B
> > > > Fax: (507) 284-9171 200 First Street SW
> > > > E-mail: daniel.erik@mayo.edu Rochester, MN 55905
> > > > ==================================================================
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: zanella, fabrizio [mailto:zanella_fabrizio@emc.com]
> > > > > Sent: Thursday, October 19, 2000 2:44 PM
> > > > > To: SI List (E-mail)
> > > > > Subject: [SI-LIST] : Differential TDR probes
> > > > >
> > > > >
> > > > > We're having problems getting a good high frequency launch
> > > > > when probing pc
> > > > > boards and cable differential pairs when taking TDR
> > > > > measurements.Has anyone
> > > > > found good differential TDR probes which allow you to measure
> > > > > very closely
> > > > > spaced points on pc boards or cables?
> > > > >
> > > > > Thanks and regards,
> > > > > Fabrizio Zanella
> > > > > Hardware Engineering
> > > > > EMC Corporation
> > > > > fzanella@emc.com
> > > > >
> > > > >
> > > > > **** To unsubscribe from si-list or si-list-digest: send e-mail to
> > > > > majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE
> > > > > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
> > > > > si-list archives are accessible at http://www.qsl.net/wb6tpu
> > > > > ****
> > > > >
> > > >
> > > > **** To unsubscribe from si-list or si-list-digest: send e-mail to
> > > > majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE>
> > > > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
> > > > si-list archives are accessible at http://www.qsl.net/wb6tpu
> > > > ****
> > > >
> > > > ------------------------------
> > > >
> > > > Date: Thu, 19 Oct 2000 15:38:44 -0700
> > > > From: John Fisher <jmfisher@cisco.com>
> > > > Subject: Re: [SI-LIST] : Differential TDR probes
> > > >
> > > > <html>
> > > > <font size=3>Fabrizio,<br>
> > > > <br>
> > > > We have built these using equal length sections of semi rigid coax with
> > > > sma's at one end. The semi rigid copper outer shield is soldered together
> > > > approx. every 3 &quot;.&nbsp; Prepare the ends by careful cutting of the
> > > > shield with an exacto knife,&nbsp; than solder the center conductors to
> > > > the launch point vias or pads. Tektronix shipped some of&nbsp; these to
> > > > us as accessories when we bought their IPA-510 a few years ago.&nbsp; I
> > > > might be able to find a tek part number but someone like Micro-Coax could
> > > > make some for you or find an off the shelf semi rigid assembly with sma's
> > > > on both ends and then just cut it in half. Be carful not to bend it too
> > > > much and kink it.&nbsp; These can also make nice 50 Ohm 10x passive
> > > > probes with the addition of a series 450 resistor at the end.<br>
> > > > <br>
> > > > Regards<br>
> > > > <br>
> > > > John<br>
> > > > <br>
> > > > At 03:44 PM 10/19/00 -0400, you wrote:<br>
> > > > <blockquote type=cite cite>We're having problems getting a good high
> > > > frequency launch when probing pc<br>
> > > > boards and cable differential pairs when taking TDR measurements.Has
> > > > anyone<br>
> > > > found good differential TDR probes which allow you to measure very
> > > > closely<br>
> > > > spaced points on pc boards or cables?<br>
> > > > <br>
> > > > Thanks and regards,<br>
> > > > Fabrizio Zanella<br>
> > > > Hardware Engineering<br>
> > > > EMC Corporation<br>
> > > > fzanella@emc.com<br>
> > > > <br>
> > > > <br>
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> > > > ****</font></blockquote><br>
> > > >
> > > <div>*********************************************************************</
> > > div>
> > > > <div>John M. Fisher -- Cisco Systems&nbsp; --
jmfisher@cisco.com</div>
> > > > <div>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 170 W. Tasman Dr., Bldg G, San Jose
> > > > CA 95134-1706</div>
> > > >
> > > <div><x-tab>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</x-tab>&nbsp;&n
> > > bsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
> > > > __&nbsp;&nbsp;&nbsp;
> > > >
> > > _&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nb
> > > sp;&nbsp;&nbsp;&nbsp;&nbsp;
> > > > _</div>
> > > > <div>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ________///&nbsp;&nbsp; \_/&nbsp;
> > > > \________/&nbsp; \&nbsp; ____</div>
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> > > <div><x-tab>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</x-tab><x-tab>&
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> > > > \/</div>
> > > > <div>Manager Signal Integrity, Enterprise Line of Business</div>
> > > > <div>408-527-9186,&nbsp; Page 408-308-5501, Fax 408-526-5504,&nbsp;
> > > > N6PFN</div>
> > > > *********************************************************************
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> > > >
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