[SI-LIST] Re: Ferrite bead question - Downloadable presentation
- From: "Grasso, Charles" <Charles.Grasso@xxxxxxxxxxxx>
- To: "Ray Anderson" <ray.anderson@xxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Thu, 13 Apr 2006 15:49:33 -0600
Good observation Ray. Thanks!
Best Regards
Charles Grasso
Senior Compliance Engineer
Echostar Communications Corp.
Tel: 303-706-5467
Fax: 303-799-6222
Cell: 303-204-2974
Pager/Short Message: 3032042974@xxxxxxxx
Email: charles.grasso@xxxxxxxxxxxx;
Email Alternate: chasgrasso@xxxxxxxx
-----Original Message-----
From: Ray Anderson [mailto:ray.anderson@xxxxxxxxxx]=20
Sent: Thursday, April 13, 2006 10:04 AM
To: si-list@xxxxxxxxxxxxx
Cc: Hassan O. Ali; steve weir; leeritchey@xxxxxxxxxxxxx; Grasso,
Charles; Ray Anderson
Subject: RE: [SI-LIST] Ferrite bead question - Downloadable presentation
Charles-
Interesting presentation, however it appears that Dr. Hill is addressing
the ferrite use topic almost solely from the EMI/EMC perspective and
doesn't even touch on the ugly impedance peaking resonance issues that
can ensue when the ferrite filter is driven from a low impedance source
into a moderate impedance load without taking appropriate measures to
damp that resonance.
Regards,
-Ray
Raymond Anderson
Senior Signal Integrity Staff Engineer
Product Technology Department
Advanced Package R&D
Xilinx Inc.
=20
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Grasso, Charles
Sent: Thursday, April 13, 2006 8:02 AM
To: leeritchey@xxxxxxxxxxxxx; steve weir; Hassan O. Ali;
si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Ferrite bead question - Downloadable presentation
Hi - I just remembered that Dr Lee Hill (Silent Solution)
visited us and gave a very nice seminar on EMC/SI and ferrites.
You can grab the presentation here:
http://www.ewh.ieee.org/r5/denver/rockymountainemc/archive/2003/may13/in
dex.html
Enjoy!!
Best Regards
Charles Grasso
Senior Compliance Engineer
Echostar Communications Corp.
Tel: 303-706-5467
Fax: 303-799-6222
Cell: 303-204-2974
Pager/Short Message: 3032042974@xxxxxxxx
Email: charles.grasso@xxxxxxxxxxxx;
Email Alternate: chasgrasso@xxxxxxxx
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Lee Ritchey
Sent: Wednesday, April 12, 2006 9:33 AM
To: steve weir; Hassan O. Ali; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Ferrite bead question
Steve,
I don't think I said that the use of ferrite beads was globally bad, or
at
least I did not intend to. There are cases where they have value and,
as
you point out, they have been carefully engineered to do so. I have yet
to
see an applications note that contains this careful engineering. I'm
still
looking.
> [Original Message]
> From: steve weir <weirsi@xxxxxxxxxx>
> To: <leeritchey@xxxxxxxxxxxxx>; Hassan O. Ali <hassan@xxxxxxxx>;
<si-list@xxxxxxxxxxxxx>
> Date: 4/11/2006 11:50:46 PM
> Subject: [SI-LIST] Re: Ferrite bead question
>
> Lee,
>
> I agree that application notes that seek to solve a non-specific=3D20
> problem with a non-specific set of assumptions are weak at best,
and=3D20
> dangerous at worst. But I am similarly uncomfortable with a =
global=3D20
> declaration that ferrite beads harm all designs, because that is=3D20
> demonstrably false. They harm designs where they are applied=3D20
> inappropriately. Given a specific noise profile and impedance=3D20
> profile ferrite PROPERLY APPLIED can be a useful answer. It just=3D20
> depends. For example, I can readily demonstrate for certain=3D20
> situations where by using beads PROPERLY to break up a PDS =
cleaner=3D20
> I/O with less EMI results because by breaking up the cavity we =
push=3D20
> the.resonance out to where there is far less energy exciting it =
and=3D20
> it is at a place that is easier to detune with other methods. But
to=3D20
> work, it first has to be applicable to the circumstances and it =
has=3D20
> to be implemented properly. And to your point, it would be a =
good=3D20
> idea if it is cheaper and / or technically better than=3D20
> alternatives. Misapplication of anything is bad. Just as I can=3D20
> improve some situations, I can just as easily break a working
design=3D20
> by throwing beads at it, either raising the supply impedance to =
the=3D20
> point that the load starves to death or where I move the =
resonance=3D20
> right on top of a big energy peak like a clock fundamental.
>
> I would hope that most people are smart enough to realize that if=3D20
> they stick a 10 Ohm ferrite in series with a power feed that needs
1=3D20
> or 5 or 20 mOhms that they need capacitance at sufficiently low=3D20
> inductance on the load side of the ferrite. If they don't, then
they=3D20
> don't understand the most basic issues of power delivery and are=3D20
> likely in very deep trouble all over their design. The bigger=3D20
> problem that I see with ferrite applications is that people don't=3D20
> bother to understand them and get burned by resonance at low=3D20
> frequency between the high Q inductor and their capacitor=3D20
> network. Ferrites are typically only resistive from about 1/10th
the=3D20
> peak impedance frequency on up. Ray has posted on that issue=3D20
> repeatedly. Those problems can be solved by any of a number of
well=3D20
> documented methods to insert needed damping, which have also been=3D20
> discussed on this forum at length.
>
> As Istvan has noted, if the system as a whole can tolerate higher=3D20
> noise amplitude than a small subsection, we have various=3D20
> implementation alternatives including: separate voltage
regulators,=3D20
> filters with resistors, filters with ferrites, feed through =
filters=3D20
> with X2Y(r)s, or costly brute force scaling of the entire system.
A=3D20
> proper understanding of the requirements, circumstances and skills
in=3D20
> the art will lead to effective solutions.
>
> Regards,
>
>
> Steve.
> At 01:15 PM 4/11/2006, Lee Ritchey wrote:
> >Hassan,
> >
> >You have the right idea. The problem is, the loads downstream from
the
> >ferrite bead need a low impedance source of current over a wider
range of
> >frequencies and ferrite beads prevent this.
> >
> >It is true that the usual reason given for using a ferrite bead is
there
is
> >noise on the power rails due to less than optimum design of the power
> >distribution system, which is thedesign engineer's job, not the IC
> >manufacturer. IC manufacturers need to have the power supply design
skill
> >the same as the rest of us, else how can the demonstrate and test
their
own
> >parts?
> >
> >
> > > [Original Message]
> > > From: Hassan O. Ali <hassan@xxxxxxxx>
> > > To: <si-list@xxxxxxxxxxxxx>
> > > Date: 4/11/2006 11:08:30 AM
> > > Subject: [SI-LIST] Re: Ferrite bead question
> > >
> > >
> > > I always thought that ferrite beads were primarily used to
surpress
noise
> >FROM (rather
> > > than INTO) high-speed and clock-like devices. I thought
ferrite-beads
> >were used as a
> > > measure against power-supply corruption and also as an EMI
prevention. I
> >thought ferrite-
> > > beads were harmless at lower (switching) frequencies over which
voltage
> >regulator
> > > modules are supposed to operate as long as their impedances were
low
> >enough not to cause
> > > excessive voltage ripples. If the above is correct, is it then
fair to
> >blame
> > > semiconductor folks for something that board designers have to
make a
> >decision on?
> > > Please someone tell me if this understanding is wrong.
> > >
> > >
> > > Best regards.
> > >
> > > Hassan.
> > >
> > >
> > >
> > > On Apr 11, <art_porter@xxxxxxxxxxx> wrote:
> > > >
> > > > Back in the good old days when I was actually designing stuff
instead
> >of =3D3D
> > > > trying to sell stuff, use of beads was considered a serious sign
of
=3D3D
> > > > weakness.=3D3D20
> > > > But like anything else, if it works, fine, but you need to
understand =3D3D
> > > > why it works. If you understand why a bead works, often that
will
lead =3D3D
> > > > to an insight as to how to fix the problem without using a
bead.=3D3D20
> > > >
> > > > Art Porter
> > > > Agilent =3D3D20
> > > >
> > > > -----Original Message-----
> > > > From: si-list-bounce@xxxxxxxxxxxxx
> >[mailto:si-list-bounce@xxxxxxxxxxxxx] =3D3D
> > > > On Behalf Of Joel Brown
> > > > Sent: Tuesday, April 11, 2006 10:46 AM
> > > > To: leeritchey@xxxxxxxxxxxxx
> > > > Cc: Zhangkun; si-list@xxxxxxxxxxxxx
> > > > Subject: [SI-LIST] Re: Ferrite bead question
> > > >
> > > > Lee,
> > > > I can't say that I disagree with any of the points you made.
> > > > The problem is these days semiconductor companies have changed
their=3D3D20
> > > > support model.
> > > > Most have done way with FAEs and factory applications engineers
> >unless=3D3D20
> > > > maybe if you are a large customer.
> > > > More often than not support is provided by email and the
responses
> >are=3D3D20
> > > > slow in coming and usually don't adequately address the
question.
> > > > Now when I encounter an application note with a ferrite =3D
bead=3D3D20
> > > > recommended, the chances of the IC manufacturer providing
information=3D3D20
> > > > that meets all your criteria is slim and none. The suggestion
that
> >the=3D3D20
> > > > IC manufacturers provided a current spectrum is a good one, but
it
> >seems =3D3D
> > > >
> > > > they are more preoccupied with the inner workings of their chips
than=3D3D20
> > > > supplying information about how their parts effect the power
system.
> >My=3D3D20
> > > > inclination at this point is to include a footprint for a
ferrite
> >where=3D3D20
> > > > I think it might help, then make measurements with various
ferrite
> >beads =3D3D
> > > >
> > > > and a 0 ohm resistor and see which part results in lowest
noise=3D3D20
> > > > measurements. The only problem is that a 0 ohm resistor would
have
> >more=3D3D20
> > > > inductance than vias connecting the bypass caps directly to the
power=3D3D20
> > > > plane. This has definitely been a learning experience, thanks to
all=3D3D20
> > > > that posted responses.
> > > >
> > > > Joel
> > > >
> > > >
> > > > Lee Ritchey wrote:
> > > > > Joel,
> > > > >
> > > > >
> > > > > As others have observed, when the solution using a ferrite
bead
has =3D3D
> > > > been
> > > > > engineered to satisfy the following set of conditions it is
warranted
> >=3D3D
> > > > and
> > > > > helpful.
> > > > >
> > > > > 1. There is a problem that needs fixing.
> > > > > 2. The proposed solution fixes the problem.
> > > > > 3. The proposed solution does not cause new problems.
> > > > > 4. The proposed solution is the best solution to the problem.
> > > > >
> > > > > When you apply this set of tests to the usual applications
note
> > > > > recommendation, it often fails test number 1. The proponent
has
not
> > > > > acertained that there is a problem and what it actually looks
like.
> > > > >
> > > > > I put this question to the students in my classes at UC
Berkeley, =3D3D
> > > > nearly
> > > > > always practicing engineers. Can you show me an applications
note =3D3D
> > > > with
> > > > > analysis supporting the use of ferrite beads? So far, there
have
> >been =3D3D
> > > > no
> > > > > such examples. I keep hoping, but know that most applications
notes =3D3D
> > > > are
> > > > > not prepared that way. Soon as I find one, I'll report it in
this =3D3D
> > > > forum
> > > > > and show it in my classes- and give its author high praise for
doing =3D3D
> > > > good
> > > > > engineering.
> > > > >
> > > > > More commonly, they are justified because "we have always
done
it =3D3D
> > > > this
> > > > > way." Further, there has usually not been any exhaustive
testing
to =3D3D
> > > > insure
> > > > > the solution is valid. That is in no way good engineering.
=3D3D20
> > > > >
> > > > > I'll accept a recommendation that is accompanied by supporting
=3D3D
> > > > engineering
> > > > > analysis. Less, seems to me to be guessing and that's a good
way
to =3D3D
> > > > get in
> > > > > trouble with modern e lectronic components.
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > =3D3D20
> > > > >> [Original Message]
> > > > >> From: Joel Brown <joel@xxxxxxxxxx>
> > > > >> To: <leeritchey@xxxxxxxxxxxxx>
> > > > >> Cc: Zhangkun <zhang_kun@xxxxxxxxxx>; <si-list@xxxxxxxxxxxxx>
> > > > >> Date: 4/10/2006 10:17:06 AM
> > > > >> Subject: Re: [SI-LIST] Re: Ferrite bead question
> > > > >>
> > > > >> Lee,
> > > > >>
> > > > >> After reading the responses and giving some more thought to
this,
> >I=3D3D20
> > > > >> agree that in some situations the use of ferrite beads can be
=3D3D
> > > > detrimental.
> > > > >> In the design I am currently working on, the ferrite beads
are
> >used=3D3D20
> > > > >> mostly on low speed I/O signals and DC power to ICs that are
not
=3D3D
> > > > running=3D3D20
> > > > >> at very high speeds.
> > > > >> The highest speed part is a 100 MHz PCI Express clock buffer,
and
> >the =3D3D
> > > >
> > > > >> manufacturer does recommend to use a ferrite bead.
> > > > >> While I agree your statements have some merit, I find it
> >problematic=3D3D20
> > > > >> that you seem to be saying ferrite beads only work by luck.
> > > > >> Certainly there must be situations in which they can
predictably
be =3D3D
> > > > used=3D3D20
> > > > >> to reduce noise.
> > > > >>
> > > > >> Regards - Joel
> > > > >>
> > > > >>
> > > > >>
> > > > >> Lee Ritchey wrote:
> > > > >> =3D3D20
> > > > >>> Joel,
> > > > >>>
> > > > >>> I agree with all the respondents who have cautioned you on
the
use =3D3D
> > > > of
> > > > >>> ferrite beads in the power leads of devices. In all of the
cases, I
> > > > >>> =3D3D20
> > > > > have
> > > > > =3D3D20
> > > > >>> investigated, ferrite beads have been used to treat a
symptom
rather
> > > > >>> =3D3D20
> > > > > than
> > > > > =3D3D20
> > > > >>> the problem. The problem being that the power delivery
system
had =3D3D
> > > > too
> > > > >>> =3D3D20
> > > > > much
> > > > > =3D3D20
> > > > >>> noinse or ripple on it.
> > > > >>>
> > > > >>> Lately, I have seen many cases where placing a ferrite bead
in
the =3D3D
> > > > power
> > > > >>> lead of a device, very often the power lead of very high
speed =3D3D
> > > > serdes,
> > > > >>> =3D3D20
> > > > > has
> > > > > =3D3D20
> > > > >>> made the part perform poorly or below spec.
> > > > >>>
> > > > >>> Yes, thousands of applications notes insist that ferrite
beads
be
> > > > >>> =3D3D20
> > > > > placed in
> > > > > =3D3D20
> > > > >>> the power leads and the applications engineers will demad
you
use =3D3D
> > > > them
> > > > >>> =3D3D20
> > > > > or
> > > > > =3D3D20
> > > > >>> they won't guarantee the circuit will work properly. The
other
> >side =3D3D
> > > > of
> > > > >>> that same coin is that when you ask if they will guarantee
that
the
> > > > >>> =3D3D20
> > > > > circuit
> > > > > =3D3D20
> > > > >>> will work properly if you follow the applications note
exactly,
the
> > > > >>> =3D3D20
> > > > > answer
> > > > > =3D3D20
> > > > >>> is still no! The reason is that there has been no analysis
to
prove
> > > > >>> =3D3D20
> > > > > that
> > > > > =3D3D20
> > > > >>> the use of a ferrite bead is a good idea.=3D3D20
> > > > >>>
> > > > >>> I have measured wavforms of a 3.12 GB/S serial link where
the
eye =3D3D
> > > > just
> > > > >>> barely makes the minimum signal amplitude with the ferrite
bead
in =3D3D
> > > > place
> > > > >>> and has large amounts of margin when the ferrite bead is
shorted =3D3D
> > > > out.=3D3D20
> > > > >>> This, even with the manufacturer's recommended capacitors
> >attached.=3D3D20
> > > > >>> =3D3D20
> > > > > This
> > > > > =3D3D20
> > > > >>> data was taken from a demo board supplied by the
manufacturer
who =3D3D
> > > > was
> > > > >>> =3D3D20
> > > > > not
> > > > > =3D3D20
> > > > >>> aware of the degradation caused by the ferrite bead.
> > > > >>>
> > > > >>> The right solution is to design a power delivery system with
power
> > > > >>> =3D3D20
> > > > > supply
> > > > > =3D3D20
> > > > >>> noise within the limits of the circuits being supplied and
this
is =3D3D
> > > > not
> > > > >>> =3D3D20
> > > > > very
> > > > > =3D3D20
> > > > >>> difficult to do.
> > > > >>>
> > > > >>> I have done the SI rule generation for three terabit
routers
with
> > > > >>> thousands of 3.125 GB/S and 4.8 GB/S serial links in them
and
used =3D3D
> > > > no
> > > > >>> ferrite beads in them any where and they worked to
specification the
> > > > >>> =3D3D20
> > > > > first
> > > > > =3D3D20
> > > > >>> time wit hproper margins. So maybe people who want you to
use =3D3D
> > > > ferrite
> > > > >>> beads should be challenged with why they want you to add
these
=3D3D
> > > > parts.
> > > > >>>
> > > > >>> My fellow SI engineers call ferrite beads "voodoo" beads and
"get =3D3D
> > > > lucky"
> > > > >>> beads for good reason.
> > > > >>>
> > > > >>> This is not likely to make the ferrite bead salesmen happy,
I'm
=3D3D
> > > > sure.
> > > > >>>
> > > > >>>
> > > > >>> =3D3D20
> > > > >>> =3D3D20
> > > > >>>> [Original Message]
> > > > >>>> From: Zhangkun <zhang_kun@xxxxxxxxxx>
> > > > >>>> To: <joel@xxxxxxxxxx>; <si-list@xxxxxxxxxxxxx>
> > > > >>>> Date: 4/10/2006 1:14:21 PM
> > > > >>>> Subject: [SI-LIST] Re: Ferrite bead question
> > > > >>>>
> > > > >>>> Dear Joel
> > > > >>>>
> > > > >>>> As to my experience, it is not enough to select bead based
on
the =3D3D
> > > > P/N.
> > > > >>>> =3D3D20
> > > > >>>> =3D3D20
> > > > >>> The decoupling circuit should be considered very carefully.
> > > > >>> =3D3D20
> > > > >>> =3D3D20
> > > > >>>> In several cases, we use beads and the noise become larger.
The
> > > > >>>> =3D3D20
> > > > > following
> > > > > =3D3D20
> > > > >>>> =3D3D20
> > > > >>>> =3D3D20
> > > > >>> element should be considered:
> > > > >>> =3D3D20
> > > > >>> =3D3D20
> > > > >>>> 1.The resonance between bead and capacitor.
> > > > >>>> 2.The frequency span of the noise source.
> > > > >>>>
> > > > >>>> A simulation is suggested. It is very simple.
> > > > >>>>
> > > > >>>> Hope this is helpful
> > > > >>>>
> > > > >>>> Best Regards
> > > > >>>>
> > > > >>>> Zhangkun
> > > > >>>> 2006.4.10
> > > > >>>> ----- Original Message -----=3D3D20
> > > > >>>> From: "Joel Brown" <joel@xxxxxxxxxx>
> > > > >>>> To: <si-list@xxxxxxxxxxxxx>
> > > > >>>> Sent: Saturday, April 08, 2006 2:33 AM
> > > > >>>> Subject: [SI-LIST] Ferrite bead question
> > > > >>>>
> > > > >>>>
> > > > >>>> =3D3D20
> > > > >>>> =3D3D20
> > > > >>>>> I often see recommendations in application notes for
ferrite
> >beads =3D3D
> > > > on
> > > > >>>>> =3D3D20
> > > > >>>>> =3D3D20
> > > > >>> DC=3D3D20
> > > > >>> =3D3D20
> > > > >>> =3D3D20
> > > > >>>>> power lines. Sometimes a particular P/N is specified and
sometimes
> > > > >>>>> =3D3D20
> > > > > just=3D3D20
> > > > > =3D3D20
> > > > >>>>> an impedance is given.
> > > > >>>>> Wouldn't I want to choose a ferrite bead that has the
highest
> > > > >>>>> =3D3D20
> > > > > impedance=3D3D20
> > > > > =3D3D20
> > > > >>>>> possible at the frequencies of interest, and that the
current
=3D3D
> > > > rating
> > > > >>>>> =3D3D20
> > > > >>>>> =3D3D20
> > > > >>> and=3D3D20
> > > > >>> =3D3D20
> > > > >>> =3D3D20
> > > > >>>>> DC resistance are appropriate? Would the frequencies of
interest =3D3D
> > > > be
> > > > >>>>> =3D3D20
> > > > > the=3D3D20
> > > > > =3D3D20
> > > > >>>>> fundamental switching frequency of the part and possibly
the
3rd =3D3D
> > > > and
> > > > >>>>> =3D3D20
> > > > >>>>> =3D3D20
> > > > >>> 5th=3D3D20
> > > > >>> =3D3D20
> > > > >>> =3D3D20
> > > > >>>>> harmonics?
> > > > >>>>> Thanks - Joel
> > > > >>>>>
> > > > >>>>>
> > > > >>>>>
> > > > >>>>> -- Binary/unsupported file stripped by Ecartis --
> > > > >>>>> -- Type: text/x-vcard
> > > > >>>>> -- File: joel.vcf
> > > > >>>>>
> > > > >>>>>
> > > > >>>>>
------------------------------------------------------------------
> > > > >>>>> To unsubscribe from si-list:
> > > > >>>>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the
Subject =3D3D
> > > > field
> > > > >>>>>
> > > > >>>>> or to administer your membership from a web page, go to:
> > > > >>>>> <a href=3D3D'//www.freelists.org/webpage/si-
> > > list'>//www.freelists.org/webpage/si-list</a>
> > > > >>>>>
> > > > >>>>> For help:
> > > > >>>>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject
field
> > > > >>>>>
> > > > >>>>> List FAQ wiki page is located at:
> > > > >>>>> <a
> >href=3D3D'http://si-list.org/wiki/wiki.pl?Si-List_FAQ'>http://si-
> > > list.org/wiki/wiki.pl?Si-List_FAQ</a>
> > > > >>>>>
> > > > >>>>> List technical documents are available at:
> > > > >>>>> <a
> >href=3D3D'http://www.si-list.org'>http://www.si-list.org</a>
> > > > >>>>>
> > > > >>>>> List archives are viewable at: =3D3D20
> > > > >>>>> <a href=3D3D'//www.freelists.org/archives/si-
> > > list'>//www.freelists.org/archives/si-list</a>
> > > > >>>>> or at our remote archives:
> > > > >>>>> <a href=3D3D'http://groups.yahoo.com/group/si-
> > > list/messages'>http://groups.yahoo.com/group/si-list/messages</a>
> > > > >>>>> Old (prior to June 6, 2001) list archives are viewable at:
> > > > >>>>> <a
> >href=3D3D'http://www.qsl.net/wb6tpu'>http://www.qsl.net/wb6tpu</a>
> > > > >>>>> =3D3D20
> > > > >>>>>
> > > > >>>>> =3D3D20
> > > > >>>>> =3D3D20
> > > > >>>>
------------------------------------------------------------------
> > > > >>>> To unsubscribe from si-list:
> > > > >>>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the
Subject =3D3D
> > > > field
> > > > >>>>
> > > > >>>> or to administer your membership from a web page, go to:
> > > > >>>> <a href=3D3D'//www.freelists.org/webpage/si-
> > > list'>//www.freelists.org/webpage/si-list</a>
> > > > >>>>
> > > > >>>> For help:
> > > > >>>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject
field
> > > > >>>>
> > > > >>>> List FAQ wiki page is located at:
> > > > >>>> <a
> >href=3D3D'http://si-list.org/wiki/wiki.pl?Si-List_FAQ'>http://si-
> > > list.org/wiki/wiki.pl?Si-List_FAQ</a>
> > > > >>>>
> > > > >>>> List technical documents are available at:
> > > > >>>> <a
> >href=3D3D'http://www.si-list.org'>http://www.si-list.org</a>
> > > > >>>>
> > > > >>>> List archives are viewable at: =3D3D20
> > > > >>>> <a
href=3D3D'//www.freelists.org/archives/si-
> > > list'>//www.freelists.org/archives/si-list</a>
> > > > >>>> or at our remote archives:
> > > > >>>> <a =
href=3D3D'http://groups.yahoo.com/group/si-
> > > list/messages'>http://groups.yahoo.com/group/si-list/messages</a>
> > > > >>>> Old (prior to June 6, 2001) list archives are viewable at:
> > > > >>>> <a
> >href=3D3D'http://www.qsl.net/wb6tpu'>http://www.qsl.net/wb6tpu</a>
> > > > >>>> =3D3D20
> > > > >>>> =3D3D20
> > > > >>>> =3D3D20
> > > > >>>
------------------------------------------------------------------
> > > > >>> To unsubscribe from si-list:
> > > > >>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the
Subject
=3D3D
> > > > field
> > > > >>>
> > > > >>> or to administer your membership from a web page, go to:
> > > > >>> <a href=3D3D'//www.freelists.org/webpage/si-
> > > list'>//www.freelists.org/webpage/si-list</a>
> > > > >>>
> > > > >>> For help:
> > > > >>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject
field
> > > > >>>
> > > > >>> List FAQ wiki page is located at:
> > > > >>> <a
> >href=3D3D'http://si-list.org/wiki/wiki.pl?Si-List_FAQ'>http://si-
> > > list.org/wiki/wiki.pl?Si-List_FAQ</a>
> > > > >>>
> > > > >>> List technical documents are available at:
> > > > >>> <a
> >href=3D3D'http://www.si-list.org'>http://www.si-list.org</a>
> > > > >>>
> > > > >>> List archives are viewable at: =3D3D20
> > > > >>> <a
href=3D3D'//www.freelists.org/archives/si-
> > > list'>//www.freelists.org/archives/si-list</a>
> > > > >>> or at our remote archives:
> > > > >>> <a =
href=3D3D'http://groups.yahoo.com/group/si-
> > > list/messages'>http://groups.yahoo.com/group/si-list/messages</a>
> > > > >>> Old (prior to June 6, 2001) list archives are viewable at:
> > > > >>> <a=3D20
> > href=3D3D'http://www.qsl.net/wb6tpu'>http://www.qsl.net/wb6tpu</a>
> > > > >>> =3D3D20
> > > > >>>
> > > > >>>
> > > > >>> =3D3D20
> > > > >>> =3D3D20
> > > > >
> > > > >
> > > > >
------------------------------------------------------------------
> > > > > To unsubscribe from si-list:
> > > > > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the
Subject
field
> > > > >
> > > > > or to administer your membership from a web page, go to:
> > > > > <a href=3D3D'//www.freelists.org/webpage/si-
> > > list'>//www.freelists.org/webpage/si-list</a>
> > > > >
> > > > > For help:
> > > > > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
> > > > >
> > > > > List FAQ wiki page is located at:
> > > > > <a
> >href=3D3D'http://si-list.org/wiki/wiki.pl?Si-List_FAQ'>http://si-
> > > list.org/wiki/wiki.pl?Si-List_FAQ</a>
> > > > >
> > > > > List technical documents are available at:
> > > > > <a
> >href=3D3D'http://www.si-list.org'>http://www.si-list.org</a>
> > > > >
> > > > > List archives are viewable at: =3D3D20
> > > > > <a href=3D3D'//www.freelists.org/archives/si-
> > > list'>//www.freelists.org/archives/si-list</a>
> > > > > or at our remote archives:
> > > > > <a href=3D3D'http://groups.yahoo.com/group/si-
> > > list/messages'>http://groups.yahoo.com/group/si-list/messages</a>
> > > > > Old (prior to June 6, 2001) list archives are viewable at:
> > > > > <a=3D20
> > href=3D3D'http://www.qsl.net/wb6tpu'>http://www.qsl.net/wb6tpu</a>
> > > > > =3D3D20
> > > > >
> > > > >
> > > > > =3D3D20
> > > >
> > > >
> > > > -- Binary/unsupported file stripped by Ecartis --
> > > > -- Type: text/x-vcard
> > > > -- File: joel.vcf
> > > >
> > > >
> > > >
------------------------------------------------------------------
> > > > To unsubscribe from si-list:
> > > > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject
field
> > > >
> > > > or to administer your membership from a web page, go to:
> > > > <a
>
>href=3D3D'//www.freelists.org/webpage/si-list'>http://www.freelists=
.
o=3D
r
g/we
b
> >page/si-
> > > list</a>
> > > >
> > > > For help:
> > > > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
> > > >
> > > > List FAQ wiki page is located at:
> > > > <a
> >href=3D3D'http://si-list.org/wiki/wiki.pl?Si-List_FAQ'>http://si-
> > > list.org/wiki/wiki.pl?Si-List_FAQ</a>
> > > >
> > > > List technical documents are available at:
> > > > <a
> >href=3D3D'http://www.si-list.org'>http://www.si-list.org</a>
> > > >
> > > > List archives are viewable at: =3D3D20
> > > > <a href=3D3D'//www.freelists.org/archives/si-
> > > list'>//www.freelists.org/archives/si-list</a>
> > > > or at our remote archives:
> > > > <a href=3D3D'http://groups.yahoo.com/group/si-
> > > list/messages'>http://groups.yahoo.com/group/si-list/messages</a>
> > > > Old (prior to June 6, 2001) list archives are viewable at:
> > > > <a=3D20
> > href=3D3D'http://www.qsl.net/wb6tpu'>http://www.qsl.net/wb6tpu</a>
> > > > =3D3D20
> > > >
> > > >
------------------------------------------------------------------
> > > > To unsubscribe from si-list:
> > > > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject
field
> > > >
> > > > or to administer your membership from a web page, go to:
> > > > <a
>
>href=3D3D'//www.freelists.org/webpage/si-list'>http://www.freelists=
.
o=3D
r
g/we
b
> >page/si-
> > > list</a>
> > > >
> > > > For help:
> > > > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
> > > >
> > > > List FAQ wiki page is located at:
> > > > <a
> >href=3D3D'http://si-list.org/wiki/wiki.pl?Si-List_FAQ'>http://si-
> > > list.org/wiki/wiki.pl?Si-List_FAQ</a>
> > > >
> > > > List technical documents are available at:
> > > > <a
> >href=3D3D'http://www.si-list.org'>http://www.si-list.org</a>
> > > >
> > > > List archives are viewable at:
> > > > <a href=3D3D'//www.freelists.org/archives/si-
> > > list'>//www.freelists.org/archives/si-list</a>
> > > > or at our remote archives:
> > > > <a href=3D3D'http://groups.yahoo.com/group/si-
> > > list/messages'>http://groups.yahoo.com/group/si-list/messages</a>
> > > > Old (prior to June 6, 2001) list archives are viewable at:
> > > > <a=3D20
> > href=3D3D'http://www.qsl.net/wb6tpu'>http://www.qsl.net/wb6tpu</a>
> > > >
> > > >
> > > >
> > > ------------------------------------------------------------------
> > > To unsubscribe from si-list:
> > > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject
field
> > >
> > > or to administer your membership from a web page, go to:
> > > //www.freelists.org/webpage/si-list
> > >
> > > For help:
> > > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
> > >
> > > List FAQ wiki page is located at:
> > > http://si-list.org/wiki/wiki.pl?Si-List_FAQ
> > >
> > > List technical documents are available at:
> > > http://www.si-list.org
> > >
> > > List archives are viewable at:
> > > //www.freelists.org/archives/si-list
> > > or at our remote archives:
> > > http://groups.yahoo.com/group/si-list/messages
> > > Old (prior to June 6, 2001) list archives are viewable at:
> > > http://www.qsl.net/wb6tpu
> > >
> >
> >
> >------------------------------------------------------------------
> >To unsubscribe from si-list:
> >si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
> >
> >or to administer your membership from a web page, go to:
> >//www.freelists.org/webpage/si-list
> >
> >For help:
> >si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
> >
> >List FAQ wiki page is located at:
> > http://si-list.org/wiki/wiki.pl?Si-List_FAQ
> >
> >List technical documents are available at:
> > http://www.si-list.org
> >
> >List archives are viewable at:
> > //www.freelists.org/archives/si-list
> >or at our remote archives:
> > http://groups.yahoo.com/group/si-list/messages
> >Old (prior to June 6, 2001) list archives are viewable at:
> > http://www.qsl.net/wb6tpu
> >
>
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
> or to administer your membership from a web page, go to:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
> List FAQ wiki page is located at:
> http://si-list.org/wiki/wiki.pl?Si-List_FAQ
>
> List technical documents are available at:
> http://www.si-list.org
>
> List archives are viewable at: =3D20
> //www.freelists.org/archives/si-list
> or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
> =3D20
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at: =3D20
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
=3D20
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at: =20
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
=20
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
