Dave:
Yes. The current-sensing transducer that I built ("Pelligrini Target") is
per the Annex B drawings in EN 61000-4-2:1995 + A1:1998 +A2:2001. It has
five paralleled 240 Ohm resistors arranged radially around the oscilloscope
side to give 48 Ohms. On the ESD Gun side are twenty-five radially spaced
50 Ohm resistors to give 2 Ohms. Transconductance is 1 Amp/1 Volt into 50
Ohms.
The present Standard requires a minimum 1 GHz bandwidth oscilloscope.
I use a Pasternak Model PE7002-30 (DC to 2 GHz) 1 Watt Attenuator between
the Pelligrini Target and the scope (voltage ratio of 32). The oscilloscope
is a Tektronix 7104 with 7B10 time base, and a 7A26 dual-trace amplifier.
I'll email a couple of photos to you (offline), and copy Mr. Pommerenke and
Mr. Kinney.
Regards,
Jim Ericson
Acme Testing Company
[email protected]
----- Original Message -----
From: "drcuthbert" <[email protected]>
To: "'Jim Ericson'" <[email protected]>
Sent: Friday, May 02, 2003 8:07 AM
Subject: RE: ESD Gun "verification"
> Jim,
>
> I simulated this. I am assuming the circuit is a 2 ohm resistor to GND. If
so, the series inductance must be <0.1 nH for the 2 ohm resistor. Does this
sound right? I can do this with 25 paralleled 49.9 ohm resistors arranged
radially around the input (discharge) point.
>
> Dave Cuthbert
> Micron Technology
>
> -----Original Message-----
> From: Jim Ericson [mailto:[email protected]]
> Sent: Thursday, May 01, 2003 11:50 PM
> To: emcpost
> Subject: ESD Gun "verification"
>
>
>
> John:
>
> I faced the same problem about six years ago. I needed to do
"verification"
> in between the expensive annual "calibrations". I first explored the
option
> of buying a Pelligrini Target. As I recall, the quotes I received were
> around $2000. That seemed outrageous, so I decided to build one myself.
> I'll bet it took me at least 3 days to make sense of those goofy
mechanical
> drawings in 61000-4-2. If only they had included a photograph or good
> cross-section in the Standard!
>
> Anyway, I finally figured it out, translated the drawings into something
> understandable by a U.S. machine shop, and got all the brass parts
> fabricated locally. It took several in-process consulting sessions with
the
> machinist, but I finally got all the brass parts done for around $300.
> Then, I purchased a $25 silver electroplating kit. It was like Science
Fair
> time in my workshop! Some hours of painstaking soldering later, the
target
> was completed. I mounted it over a specially-drilled hole in the brass
wall
> panel of our anechoic chamber (you need a Faraday Cage of some sort, and
> this seemed the easiest). I did a quick check using our Tektronix 1 GHz
> analog oscilloscope ... and the risetimes and overall waveforms measured
> within spec! Then, I sent the target to Haefely-Trench for a
"calibration"
> (against their standard Pelligrini target). The results were very, very
> close.
>
> Having performed many verifications at this point, my advice (if you want
> fairly accurate and repeatable results):
>
> 1. Make (or buy) something resembling the 61000-4-2 target.
> 2. Use a Faraday Cage.
> 3. Be aware how important the POSITION of the ESD Gun Grounding Strap
is
> to these measurements ... especially to risetime measurements. I always
> take a photograph of the setup, including the "shape" of the Grounding
Strap
> and where it is attached. If you don't do this, you'll get pretty wild
> variability between verifications.
> 4. Even a 500 MHz oscilloscope would probably be OK for "verification".
> Just make certain that all setup parameters (including Ground Strap
> placement) are EXACTLY the same each time. That way, if the GUN happens
to
> change, you'll at least know what to do next.
>
> Give me a call if you'd like a photo.
>
> Good luck!
>
> Jim Ericson
> Quality System Manager/Sr. EMC Engineer
> Acme Testing Company
> Acme, WA.
> 888-226-3837
> [email protected]
>
> ----- Original Message -----
> From: "John Harrington" <[email protected]>
> To: <[email protected]>
> Sent: Thursday, May 01, 2003 11:45 AM
> Subject: ESD gun verification
>
>
> >
> > Hello All
> >
> > Does any one have a quick and dirty (and hopefully cheap) way to verify
> the
> > performance of an ESD gun.
> >
> > Please, no one suggest building the current sensing system described in
> the
> > back of IEC 61000-4-2. I don't understand the drawings let alone have
the
> > workshop or materials to consider it. Although, I may pay someone to
> build
> > it for me...
> >
> > I am desperate enough to consider buying something off the shelf (if I
> could
> > find said shelf).
> >
> > All help appreciated
> >
> > John Harrington
> > EMC Technical Manager
> > F-Squared Laboratories
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