[SI-LIST] Fw: Re: Inexpensive TDR for short/open localizing on a PCB
- From: olaney@xxxxxxxx
- To: jmartinson@xxxxxxxxxxxxxxxxx
- Date: Thu, 3 May 2007 10:10:16 -0700
Lee is probably right. This is the sort of thing that I recommend be
purchased used, either through a dealer for a refurb'ed unit with a
warranty, or else e-bay if bottom dollar is the goal. My shop is very
happy with an Agilent 54754A dual TDR that includes differential
measurements (better than equivalent Tek gear in my opinion due to a
superior implementation) and TDT. Spatial resolution is about a quarter
inch, or if well calibrated and some noise is tolerable, down to nearly a
tenth inch. A plus is that the 54754A is not just a TDR, but also
doubles as a dual channel sampling scope with a bandwidth of 18 GHz. The
86100 mainframe includes automated analysis of risetime, eye patterns,
etc. and includes export of screen shots that can be pasted into a
document, etc. If only a single channel is required, the 54753A is
cheaper. You can get the 86100A used. The current 86100C is required
only if you demand new or need the jitter analysis capability. Agilent
also sells an articulated probe holder that does a lot to solve the
problem of connecting the TDR to PCB traces (N1020A). This is a
universal fixture that can be used with any TDR, and can also be found
used. The PWB fabrication industry uses a lot of TDR equipment from
Polar Instruments. That might be another direction to check. The
capability seems more modest than full blown lab gear, which is probably
sufficient for casual troubleshooting of the sort that you contemplate,
but I don't know if it is necessarily cheaper.
I'm hesitant to reply to the entire list, because the automated "out of
office" replies are a pain in a tender place. Why there isn't a facility
to suppress auto responses to list servers speaks to why so much software
is terrible -- it's written by programmers rather than by users.
Orin Laney
Atwood Research
Jerry,
The least expensive TDR I know of that will suit you purpose is the
Tektronix 1502C.
Lee
> [Original Message]
> From: Jerry Martinson <jmartinson@xxxxxxxxxxxxxxxxx>
> To: si-list <si-list@xxxxxxxxxxxxx>
> Date: 5/2/2007 10:54:14 AM
> Subject: [SI-LIST] Inexpensive TDR for short/open localizing on a PCB
>
> Sorry if this seems a bit off-topic.
>
>
> Does anybody know of an inexpensive and easy-to-use TDR system that's
> good enough to localize PCB assembly shorts and open with accuracy that
> translates into about 1 inch on a trace? I'm trying to see if I can
> find something that can help out with the old "which chip to replace"
> problem during assembly debug as often BGA x-rays are ambiguous.
>
>
>
> Jerry Martinson
>
> ARUBA NETWORKS
>
> (work 408-754-3037) (cell 408-394-5185)
>
> jmartinson@xxxxxxxxxxxxxxxxx
>
> 1322 Crossman, Sunnyvale, CA 94089
>
>
>
>
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