We made a probe using rigid coax with its built in SMA connector. Solder a
pin to the side of the coax and file it diagonally to create a sharp point.
To increase the loading impedance we used an SMA "collar" that had been
filed out to place a series chip resistor of 470 ohms in series with the
center conductor.
Then we "calibrated" the probe for insertion loss up to 2 GHz and could
probe around on the board.
If I had it to do again, I would move the resistor out very close to the
probe tip to reduce the effects of the series inductance, but what worked
worked, so we went on.
- Robert -
-----Original Message-----
From: pwmc...@ra.rockwell.com <pwmc...@ra.rockwell.com>
To: Cameron O'phee <O'p...@ali.com.au>
Cc: 'EMC - PSTC Forum' <emc-p...@majordomo.ieee.org>; Roman Seifert
<seif...@ali.com.au>
List-Post: emc-pstc@listserv.ieee.org
Date: Thursday, September 28, 2000 5:50 AM
Subject: Re: Probing power plane with analyser.
>
>
>Cameron,
> If you are looking for a measure of the conducted RF coming off the
>board the standard AC LISN works for DC power as well. The voltage probe
>per CISPR 16 will also work and gives a standardized impedance that can be
>probed from point to point (or if you are looking for a "down and dirty"
>measurement just put a capacitor in series with your probe to block the
>DC).
>
>Paul McCoy
>
>
>
>
>
>"Cameron O'phee" <O'p...@ali.com.au>@ieee.org on 09/27/2000 07:59:24 PM
>
>Please respond to "Cameron O'phee" <O'p...@ali.com.au>
>
>Sent by: owner-emc-p...@ieee.org
>
>
>To: "'EMC - PSTC Forum'" <emc-p...@majordomo.ieee.org>
>cc: Roman Seifert <seif...@ali.com.au>
>Subject: Probing power plane with analyser.
>
>
>
>Hello All,
>
>I have been asked by one of our design engineers if I can measure the RF
>signature on the 3v plane on one of our PCB designs. The purpose of this
>is
>to compare it to proposed changes for cost reduction, ie removal of bypass
>caps. I would assume I need some sort of CDN but I have no designs for
>this
>application. Does anyone have any ideas on how I can safely probe a 3v DC
>power rail with an EMC analyser (HP8591E)?
>
>
>Regards,
>
>Cameron O'Phee.
>EMC & Safety Precompliance.
>Aristocrat Technologies Australia.
>
>Telephone : +61 2 9697 4420
>Facsimile : +61 2 9663 1412
>Mobile : 0418 464 016
>
>-------------------------------------------
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