Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

[dward]

Since it is the ferrite that  is the ‘special accessory’, the company would not 
necessarily need to provide the cable, they would only have to provide the 
special accessory ferrite that would fit on the cable.  Or they would provide a 
means of obtaining the ferrite at the time of purchase for the cable.  Since 
ferrites are not typically over the counter easily accessible accessories that 
would also mean that most likely the actual ferrites would have to be provided 
along with instructions on how to install them on any cable the user purchases. 
 It does not matter if the customer purchased the cable at a later date, that 
is up to them, but what does matter is that the ferrites are dealt with AT THE 
TIME OF PURCHASE.

Thanks 

 

​

Dennis Ward

This communication and its attachements contain information from PCTEST 
Engineering Laboratory, Inc., and I sintended for the exclusive use of the 
recipient(s) named above.  It may contain information that is confidential 
and/or legally privileged.  Any unauthorized use that may compromise that 
confidentiality via distribution or disclosure is prohibited.  Please notify 
the sender immediately if you receive this communication in error, and delete 
it from your computer system.  Usage of PCTEST email addresses for non-business 
related activities is strictly prohibited.  No warranty is made that the e-mail 
or attachments(s) are free from computer virus or other defect.  Thank you.

 

From: Pat Lawler [mailto:plawl...@gmail.com] 
Sent: Sunday, September 7, 2014 6:58 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

 

All,

 

I was looking through sales ads for electronics equipment, and saw a Blu-Ray 
disc player from a major company that came with an HDMI cable.

 

In the past, I would have just considered this a convenience to the buyer, like 
including batteries for remote controls.  Now, I'm wondering if the HDMI cable 
had ferrites, or came from a qualified vendor list of known-good cable 
manufacturers.

 

If a company has to supply a cable to control emissions, does that fact need to 
be reinforced in the user's manual?  For example, 'Use only supplied HDMI cable 
or equivalent', or 'Use only company brand products for best performance.'

 

Pat Lawler

plawl...@gmail.com mailto:plawl...@gmail.com 

 

On Thu, Sep 4, 2014 at 9:31 AM, Gary McInturff gary.mcintu...@esterline.com 
mailto:gary.mcintu...@esterline.com  wrote:

Playing the devil advocate here only because I find this interesting and I'm 
not advocating anything. Heck I'm probably just arguing for argument sake.

 If all cables are not equal as Ghery and note and the designer/manufacturer 
has knowledge of that don't the cables then become special accessories in their 
own right? Under 15.27 c) They would not normally be considered special 
accessory items  under the definition because they can be easily purchased at a 
multitude of locations.
15.27 c) Accessory items that can be readily obtained from multiple 
retail outlets are NOT (my emphasis)  considered to be special accessories ...
But given the knowledge of the designer/manufacturer that cables vary in 
performance and not all cables were tested the only assurance they have that 
the system will perform as intended is buy telling the consumer exactly which 
cable they must use buy name and brand. But if they do that then the cable 
isn't readily obtained from multiple outlets and is now by definition a 
special accessory. Paragraph 15.27 says that The party responsible for the 
equipment, as detailed in §2.909 of this chapter, shall ensure that these 
special accessories are provided with the equipment So now must the cable be 
provided?


Gmac

-Original Message-
From: Pettit, Ghery [mailto:ghery.pet...@intel.com 
mailto:ghery.pet...@intel.com ]
Sent: Thursday, September 04, 2014 12:46 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG mailto:EMC-PSTC@LISTSERV.IEEE.ORG 
Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables

You are highly unlikely to find the ferrite prayer beads at Best Buy.  If you 
don't specify which ones to get you have no idea what the result will be.  I 
think you are correct, the beads must be shipped with the product.  The right 
ones, to boot.

Now, how does the designer know that he needs ferrite beads?  My experience has 
been that many (most?) HDMI cables do not have their shields terminated 
properly, if at all.  Once the shields are terminated correctly problems go 
away.  Could this be a better solution?

Ghery S. Pettit

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
emc-p...@ieee.org mailto:emc-p...@ieee.org 

All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online 

Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

[Pat Lawler]

Hi Dennis,

If the manufacturer choose to to use ferrites to solves the emissions
problem, the implementation seems clear.  Inconvenient, but clear.

What if the company found HDMI cables without ferrites that solved the
emissions problem, like cables from vendors that properly terminate the
shields to the connectors.  Is a quality cable considered 'special', and
need to be shipped with products?
Or does the issue fall into the category of using 'golden components' for
compliance testing -- the manufacturer keeps a set of good HDMI cables for
compliance testing, but doesn't ship cables with the product.  I'm reminded
of discussions on the listserver about selecting a brand of PC for
peripheral testing, or having a particular PC with all the screws tightened
and shielding contact surfaces polished clean.

Pat Lawler
plawl...@gmail.com


On Mon, Sep 8, 2014 at 7:47 AM, dward dw...@pctestlab.com wrote:

 Since it is the ferrite that  is the ‘special accessory’, the company
 would not necessarily need to provide the cable, they would only have to
 provide the special accessory ferrite that would fit on the cable.  Or they
 would provide a means of obtaining the ferrite at the time of purchase for
 the cable.  Since ferrites are not typically over the counter easily
 accessible accessories that would also mean that most likely the actual
 ferrites would have to be provided along with instructions on how to
 install them on any cable the user purchases.  It does not matter if the
 customer purchased the cable at a later date, that is up to them, but what
 does matter is that the ferrites are dealt with AT THE TIME OF PURCHASE.

 Thanks



 ​

 Dennis Ward

 This communication and its attachements contain information from PCTEST
 Engineering Laboratory, Inc., and I sintended for the exclusive use of the
 recipient(s) named above.  It may contain information that is confidential
 and/or legally privileged.  Any unauthorized use that may compromise that
 confidentiality via distribution or disclosure is prohibited.  Please
 notify the sender immediately if you receive this communication in error,
 and delete it from your computer system.  Usage of PCTEST email addresses
 for non-business related activities is strictly prohibited.  No warranty is
 made that the e-mail or attachments(s) are free from computer virus or
 other defect.  Thank you.



 *From:* Pat Lawler [mailto:plawl...@gmail.com]
 *Sent:* Sunday, September 7, 2014 6:58 AM
 *To:* EMC-PSTC@LISTSERV.IEEE.ORG
 *Subject:* Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum



 All,



 I was looking through sales ads for electronics equipment, and saw a
 Blu-Ray disc player from a major company that came with an HDMI cable.



 In the past, I would have just considered this a convenience to the buyer,
 like including batteries for remote controls.  Now, I'm wondering if the
 HDMI cable had ferrites, or came from a qualified vendor list of known-good
 cable manufacturers.



 If a company has to supply a cable to control emissions, does that fact
 need to be reinforced in the user's manual?  For example, 'Use only
 supplied HDMI cable or equivalent', or 'Use only company brand products
 for best performance.'



 Pat Lawler

 plawl...@gmail.com



 On Thu, Sep 4, 2014 at 9:31 AM, Gary McInturff 
 gary.mcintu...@esterline.com wrote:

 Playing the devil advocate here only because I find this interesting and
 I'm not advocating anything. Heck I'm probably just arguing for argument
 sake.

  If all cables are not equal as Ghery and note and the
 designer/manufacturer has knowledge of that don't the cables then become
 special accessories in their own right? Under 15.27 c) They would not
 normally be considered special accessory items  under the definition
 because they can be easily purchased at a multitude of locations.
 15.27 c) Accessory items that can be readily obtained from
 multiple retail outlets are NOT (my emphasis)  considered to be special
 accessories ...
 But given the knowledge of the designer/manufacturer that cables vary in
 performance and not all cables were tested the only assurance they have
 that the system will perform as intended is buy telling the consumer
 exactly which cable they must use buy name and brand. But if they do that
 then the cable isn't readily obtained from multiple outlets and is now by
 definition a special accessory. Paragraph 15.27 says that The party
 responsible for the equipment, as detailed in §2.909 of this chapter, shall
 ensure that these special accessories are provided with the equipment So
 now must the cable be provided?


 Gmac

 -Original Message-
 From: Pettit, Ghery [mailto:ghery.pet...@intel.com]
 Sent: Thursday, September 04, 2014 12:46 AM
 To: EMC-PSTC@LISTSERV.IEEE.ORG
 Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables

 You are highly unlikely to find the ferrite prayer beads at Best Buy.  If
 you don't specify which ones to get you have no idea what the result 

Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

[Cortland Richmond]

 Around1991 I was able to demonstrate that a computer that must be shipped with a really well shielded printer cable must also be shipped with really well shielded PRINTER. Luckily, I caught it before we sent it out for an FCC ID, and minor rework made the the poorly placed bypass capacitors effective again.Cortland Richmond-Original Message-
From: Pat Lawler 
Sent: Sep 8, 2014 12:05 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

Hi Dennis,If the manufacturer choose to to use ferrites to solves the emissions problem, the implementation seems clear. Inconvenient, but clear.What if the company found HDMI cables without ferrites that solved the emissions problem, like cables from vendors that properly terminate the shields to the connectors. Is a quality cable considered 'special', and need to be shipped with products?Or does the issue fall into the category of using 'golden components' for compliance testing -- the manufacturer keeps a set of good HDMI cables for compliance testing, but doesn't ship cables ...
-

This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
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Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc.


Website:  http://www.ieee-pses.org/
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List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
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Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

[Pat Lawler]

All,

I was looking through sales ads for electronics equipment, and saw a
Blu-Ray disc player from a major company that came with an HDMI cable.

In the past, I would have just considered this a convenience to the buyer,
like including batteries for remote controls.  Now, I'm wondering if the
HDMI cable had ferrites, or came from a qualified vendor list of known-good
cable manufacturers.

If a company has to supply a cable to control emissions, does that fact
need to be reinforced in the user's manual?  For example, 'Use only
supplied HDMI cable or equivalent', or 'Use only company brand products
for best performance.'

Pat Lawler
plawl...@gmail.com

On Thu, Sep 4, 2014 at 9:31 AM, Gary McInturff gary.mcintu...@esterline.com
 wrote:

 Playing the devil advocate here only because I find this interesting and
 I'm not advocating anything. Heck I'm probably just arguing for argument
 sake.

  If all cables are not equal as Ghery and note and the
 designer/manufacturer has knowledge of that don't the cables then become
 special accessories in their own right? Under 15.27 c) They would not
 normally be considered special accessory items  under the definition
 because they can be easily purchased at a multitude of locations.
 15.27 c) Accessory items that can be readily obtained from
 multiple retail outlets are NOT (my emphasis)  considered to be special
 accessories ...
 But given the knowledge of the designer/manufacturer that cables vary in
 performance and not all cables were tested the only assurance they have
 that the system will perform as intended is buy telling the consumer
 exactly which cable they must use buy name and brand. But if they do that
 then the cable isn't readily obtained from multiple outlets and is now by
 definition a special accessory. Paragraph 15.27 says that The party
 responsible for the equipment, as detailed in §2.909 of this chapter, shall
 ensure that these special accessories are provided with the equipment So
 now must the cable be provided?


 Gmac

 -Original Message-
 From: Pettit, Ghery [mailto:ghery.pet...@intel.com]
 Sent: Thursday, September 04, 2014 12:46 AM
 To: EMC-PSTC@LISTSERV.IEEE.ORG
 Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables

 You are highly unlikely to find the ferrite prayer beads at Best Buy.  If
 you don't specify which ones to get you have no idea what the result will
 be.  I think you are correct, the beads must be shipped with the product.
 The right ones, to boot.

 Now, how does the designer know that he needs ferrite beads?  My
 experience has been that many (most?) HDMI cables do not have their shields
 terminated properly, if at all.  Once the shields are terminated correctly
 problems go away.  Could this be a better solution?

 Ghery S. Pettit

 -
 
 This message is from the IEEE Product Safety Engineering Society emc-pstc
 discussion list. To post a message to the list, send your e-mail to 
 emc-p...@ieee.org

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 http://www.ieee-pses.org/emc-pstc.html

 Attachments are not permitted but the IEEE PSES Online Communities site at
 http://product-compliance.oc.ieee.org/ can be used for graphics (in
 well-used formats), large files, etc.

 Website:  http://www.ieee-pses.org/
 Instructions:  http://www.ieee-pses.org/list.html (including how to
 unsubscribe)
 List rules: http://www.ieee-pses.org/listrules.html

 For help, send mail to the list administrators:
 Scott Douglas emcp...@radiusnorth.net
 Mike Cantwell mcantw...@ieee.org

 For policy questions, send mail to:
 Jim Bacher:  j.bac...@ieee.org
 David Heald: dhe...@gmail.com


-

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Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

[Doug Powell]

Pat,It is incumbent on the original manufacturer to include any information pertinent to the correct use and operation of the product. ‎Many manufacturers have a "Conditions of Use" section in in their user manuals right behind the safety section. Of course would include any required I/O cables. As for supplying the correct cable, many products in the past had non-detachable cords with a molded in ferrite, nowadays with so much modularity, this is not always the case. HDMI cables being one example.  ‎If it were my product, I would have a few options. Ship one cable of the correct type with each product, make the same cable available as an accessory or replacement part and finally add a disclaimer stating other similar cables will not perform to the same level of expectation and will exceed emissions limits. In other words, use only the cable provided by the company. By so doing, the liability of misuse of the product stays with the end user.If you start down the path of describing a certain brand of cable (not your own), a certain type of ferrite (not available to most end users) and a certain positioning of the ferrite on the cable, you are now advising the end user on their own application and thereby assuming liability for any interference. It is best to keep it simple and to the point. Make available a complete setup that actually works. If the end user chooses to go another route, it is on their own head.   Thanks, - dougDouglas Powellhttp://www.linkedin.com/in/dougp01  From: Pat LawlerSent: Sunday, September 7, 2014 7:59 AMTo: EMC-PSTC@LISTSERV.IEEE.ORGReply To: Pat LawlerSubject: Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrumAll,I was looking through sales ads for electronics equipment, and saw a Blu-Ray disc player from a major company that came with an HDMI cable.In the past, I would have just considered this a convenience to the buyer, like including batteries for remote controls. Now, I'm wondering if the HDMI cable had ferrites, or came from a qualified vendor list of known-good cable manufacturers.If a company has to supply a cable to control emissions, does that fact need to be reinforced in the user's manual? For example, 'Use only supplied HDMI cable or equivalent', or 'Use only company brand products for best performance.'Pat Lawlerplawl...@gmail.comOn Thu, Sep 4, 2014 at 9:31 AM, Gary McInturff gary.mcintu...@esterline.com wrote:Playing the devil advocate here only because I find this interesting and I'm not advocating anything. Heck I'm probably just arguing for argument sake.

If all cables are not equal as Ghery and note and the designer/manufacturer has knowledge of that don't the cables then become special accessories in their own right? Under 15.27 c) They would not normally be considered special accessory items under the definition because they can be easily purchased at a multitude of locations.
15.27 c) Accessory items that can be readily obtained from multiple retail outlets are NOT (my emphasis) considered to be special accessories ...
But given the knowledge of the designer/manufacturer that cables vary in performance and not all cables were tested the only assurance they have that the system will perform as intended is buy telling the consumer exactly which cable they must use buy name and brand. But if they do that then the cable isn't "readily obtained from multiple outlets" and is now by definition a special accessory. Paragraph 15.27 says that "The party responsible for the equipment, as detailed in §2.909 of this chapter, shall ensure that these special accessories are provided with the equipment" So now must the cable be provided?


Gmac

-Original Message-
From: Pettit, Ghery [mailto:ghery.pet...@intel.com]
Sent: Thursday, September 04, 2014 12:46 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables

You are highly unlikely to find the ferrite prayer beads at Best Buy. If you don't specify which ones to get you have no idea what the result will be. I think you are correct, the beads must be shipped with the product. The right ones, to boot.

Now, how does the designer know that he needs ferrite beads? My experience has been that many (most?) HDMI cables do not have their shields terminated properly, if at all. Once the shields are terminated correctly problems go away. Could this be a better solution?

Ghery S. Pettit

-

This message is from the IEEE 

Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

[Bill Owsley]

For the FCC as noted in the post, special equipment, that is the stuff needed 
to pass the test, must be supplied with the equipment with instructions for 
using it.  For example, the ferrites originally mentioned.   In the EU, this 
has been held to be too complicated for the common consumer and so the ferrites 
have to be installed on the equipment that needs them, which means a cable with 
ferrite being shipped with each unit.  That might be enough motivation, to go 
fix the problem as many other posted have mentioned.
A good test lab will have noted that in the test report.  So any calling for 
the test report can see for themselves what is needed.



On Sunday, September 7, 2014 10:03 AM, Pat Lawler plawl...@gmail.com wrote:
 



All,


I was looking through sales ads for electronics equipment, and saw a Blu-Ray 
disc player from a major company that came with an HDMI cable.


In the past, I would have just considered this a convenience to the buyer, 
like including batteries for remote controls.  Now, I'm wondering if the HDMI 
cable had ferrites, or came from a qualified vendor list of known-good cable 
manufacturers.


If a company has to supply a cable to control emissions, does that fact need 
to be reinforced in the user's manual?  For example, 'Use only supplied HDMI 
cable or equivalent', or 'Use only company brand products for best 
performance.'


Pat Lawler
plawl...@gmail.com


On Thu, Sep 4, 2014 at 9:31 AM, Gary McInturff gary.mcintu...@esterline.com 
wrote:

Playing the devil advocate here only because I find this interesting and I'm 
not advocating anything. Heck I'm probably just arguing for argument sake.

 If all cables are not equal as Ghery and note and the designer/manufacturer 
 has knowledge of that don't the cables then become special accessories in 
 their own right? Under 15.27 c) They would not normally be considered 
 special accessory items  under the definition because they can be easily 
 purchased at a multitude of locations.
15.27 c) Accessory items that can be readily obtained from multiple 
 retail outlets are NOT (my emphasis)  considered to be special accessories 
 ...
But given the knowledge of the designer/manufacturer that cables vary in 
performance and not all cables were tested the only assurance they have that 
the system will perform as intended is buy telling the consumer exactly which 
cable they must use buy name and brand. But if they do that then the cable 
isn't readily obtained from multiple outlets and is now by definition a 
special accessory. Paragraph 15.27 says that The party responsible for the 
equipment, as detailed in §2.909 of this chapter, shall ensure that these 
special accessories are provided with the equipment So now must the cable be 
provided?


Gmac

-Original Message-
From: Pettit, Ghery [mailto:ghery.pet...@intel.com]
Sent: Thursday, September 04, 2014 12:46 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables

You are highly unlikely to find the ferrite prayer beads at Best Buy.  If you 
don't specify which ones to get you have no idea what the result will be.  I 
think you are correct, the beads must be shipped with the product.  The right 
ones, to boot.

Now, how does the designer know that he needs ferrite beads?  My experience 
has been that many (most?) HDMI cables do not have their shields terminated 
properly, if at all.  Once the shields are terminated correctly problems go 
away.  Could this be a better solution?

Ghery S. Pettit

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
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All emc-pstc postings are archived and searchable on the web at:
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Attachments are not permitted but the IEEE PSES Online Communities site at 
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formats), large files, etc.

Website:  http://www.ieee-pses.org/
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List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
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-


This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
emc-p...@ieee.org
All emc-pstc postings are archived and searchable on the web at: 
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Attachments are not permitted but the IEEE PSES Online Communities site at 
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formats), large files, etc.
Website: http://www.ieee-pses.org/

Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

[CR]

On 9/4/2014 4:56 PM, Ravinder Ajmani wrote:

  Most of the products our lab tested were PCs (XT, AT), and peripherals 
(printers, monitors, Modems, Display Adapters, etc).  Printer cable was always 
a key issue.  We would always use Belden cables with the printers, as they were 
double shielded with proper shield termination.  If ferrite clamps were 
required to pass then the report would state


I was there then too -- and it did not take very long to sink in that 
selling a computer that uses peripheral cables as RF transmission lines 
to unshielded printers etc. was a BAD idea!


One fix involved bypassing the noise reducing  isolated ground at 
the printer connector, the designer having cleverly put all the parallel 
output bypasses *inside* an isolated ground. Current has to be put back 
where it came from or it will go elsewhere.



Cortland Richmond

-

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Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

[Pawson, James]

But John, HDMI uses a differential signalling interface which is known to 
provide low emissions!  8-)

-Original Message-
From: John Woodgate [mailto:j...@jmwa.demon.co.uk] 
Sent: 04 September 2014 19:44
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

In message
63e38a5b081437478c77651f3d56c64f580a3...@orsmsx102.amr.corp.intel.com,
dated Thu, 4 Sep 2014, Pettit, Ghery ghery.pet...@intel.com writes:

The problem with HDMI cables is that the HDMI standards for the cables 
do not specify that the shields be terminated.

Is anyone complaining to HDMI about that? It seems incredible, considering the 
status of the consortium companies that developed the interface, that the EMC 
issue was not treated in depth. Even if shielding was deemed optional (why?), 
at least the termination of shielding could have been specified.
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Quid 
faciamus nisi sit?
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

-

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Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

[John Woodgate]

In message 
cec6039c09630543852b1a8cfa0a0c790de63...@stwpiexc03.sats.corp, dated 
Fri, 5 Sep 2014, Pawson, James james.paw...@echostar.com writes:


But John, HDMI uses a differential signalling interface which is known 
to provide low emissions!  8-)


Oh, right. So no ferrites are actually necessary, ever.

Seriously, two things:

1. If there is a shield and it's not terminated properly (keeping the 
impedance low), it can radiate stuff that comes from the grounds of the 
equipment, perhaps nothing to do with the HDMI interface itself.


2. There is/was an astonishing amount of 'don't know' about differential 
interfaces, even, apparently in some EMC standards committees, and it 
hasn't entirely gone away yet. The main point is that a signal may start 
off differential, but any impedance discontinuity in the cable or at its 
end converts some of the signal to common mode. It doesn't need much of 
a discontinuity to produce enough common-mode current to challenge the 
emission limits.


A 'pigtailed' shield can present a sufficient impedance discontinuity. 
The cable need to be treated as a 3-wire transmission line. The theory 
of 3-wire lines has already been worked out, it's nothing new.

--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
Quid faciamus nisi sit?
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

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Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

[Gary McInturff]

Playing the devil advocate here only because I find this interesting and I'm 
not advocating anything. Heck I'm probably just arguing for argument sake. 

 If all cables are not equal as Ghery and note and the designer/manufacturer 
has knowledge of that don't the cables then become special accessories in their 
own right? Under 15.27 c) They would not normally be considered special 
accessory items  under the definition because they can be easily purchased at a 
multitude of locations.
15.27 c) Accessory items that can be readily obtained from multiple 
retail outlets are NOT (my emphasis)  considered to be special accessories ...  
But given the knowledge of the designer/manufacturer that cables vary in 
performance and not all cables were tested the only assurance they have that 
the system will perform as intended is buy telling the consumer exactly which 
cable they must use buy name and brand. But if they do that then the cable 
isn't readily obtained from multiple outlets and is now by definition a 
special accessory. Paragraph 15.27 says that The party responsible for the 
equipment, as detailed in §2.909 of this chapter, shall ensure that these 
special accessories are provided with the equipment So now must the cable be 
provided?


Gmac

-Original Message-
From: Pettit, Ghery [mailto:ghery.pet...@intel.com] 
Sent: Thursday, September 04, 2014 12:46 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables

You are highly unlikely to find the ferrite prayer beads at Best Buy.  If you 
don't specify which ones to get you have no idea what the result will be.  I 
think you are correct, the beads must be shipped with the product.  The right 
ones, to boot.

Now, how does the designer know that he needs ferrite beads?  My experience has 
been that many (most?) HDMI cables do not have their shields terminated 
properly, if at all.  Once the shields are terminated correctly problems go 
away.  Could this be a better solution?

Ghery S. Pettit

-

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Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

[Pettit, Ghery]

The problem with HDMI cables is that the HDMI standards for the cables do not 
specify that the shields be terminated.  Thus, cables with improperly 
terminated shields can be labeled as HDMI compliant.  Best of luck in buying 
one off the shelf and having it done right from an EMC perspective.  You can 
specify that the customer buy properly shielded cables, but how is the customer 
going to know, short of taking a cable apart at the store (which I know the 
store won't be too happy about)?

Ghery S. Pettit

-Original Message-
From: Gary McInturff [mailto:gary.mcintu...@esterline.com] 
Sent: Thursday, September 04, 2014 9:31 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

Playing the devil advocate here only because I find this interesting and I'm 
not advocating anything. Heck I'm probably just arguing for argument sake. 

 If all cables are not equal as Ghery and note and the designer/manufacturer 
has knowledge of that don't the cables then become special accessories in their 
own right? Under 15.27 c) They would not normally be considered special 
accessory items  under the definition because they can be easily purchased at a 
multitude of locations.
15.27 c) Accessory items that can be readily obtained from multiple 
retail outlets are NOT (my emphasis)  considered to be special accessories ...  
But given the knowledge of the designer/manufacturer that cables vary in 
performance and not all cables were tested the only assurance they have that 
the system will perform as intended is buy telling the consumer exactly which 
cable they must use buy name and brand. But if they do that then the cable 
isn't readily obtained from multiple outlets and is now by definition a 
special accessory. Paragraph 15.27 says that The party responsible for the 
equipment, as detailed in §2.909 of this chapter, shall ensure that these 
special accessories are provided with the equipment So now must the cable be 
provided?


Gmac

-Original Message-
From: Pettit, Ghery [mailto:ghery.pet...@intel.com] 
Sent: Thursday, September 04, 2014 12:46 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables

You are highly unlikely to find the ferrite prayer beads at Best Buy.  If you 
don't specify which ones to get you have no idea what the result will be.  I 
think you are correct, the beads must be shipped with the product.  The right 
ones, to boot.

Now, how does the designer know that he needs ferrite beads?  My experience has 
been that many (most?) HDMI cables do not have their shields terminated 
properly, if at all.  Once the shields are terminated correctly problems go 
away.  Could this be a better solution?

Ghery S. Pettit

-

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Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

[John Woodgate]

In message 
63e38a5b081437478c77651f3d56c64f580a3...@orsmsx102.amr.corp.intel.com, 
dated Thu, 4 Sep 2014, Pettit, Ghery ghery.pet...@intel.com writes:


The problem with HDMI cables is that the HDMI standards for the cables 
do not specify that the shields be terminated.


Is anyone complaining to HDMI about that? It seems incredible, 
considering the status of the consortium companies that developed the 
interface, that the EMC issue was not treated in depth. Even if 
shielding was deemed optional (why?), at least the termination of 
shielding could have been specified.

--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
Quid faciamus nisi sit?
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

-

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Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

[Ravinder Ajmani]

A generation ago I was involved with EMI testing of computer products.  Most of 
the products our lab tested were PCs (XT, AT), and peripherals (printers, 
monitors, Modems, Display Adapters, etc).  Printer cable was always a key 
issue.  We would always use Belden cables with the printers, as they were 
double shielded with proper shield termination.  If ferrite clamps were 
required to pass then the report would state it, and customer would be advised 
to provide the ferrite clamps with the product.

Regards
Ravinder Ajmani
HGST, a Western Digital company
5601 Great Oaks Pkwy
San Jose, CA 95119-1003
ravinder.ajm...@hgst.com

-Original Message-
From: Gary McInturff [mailto:gary.mcintu...@esterline.com] 
Sent: Thursday, September 04, 2014 9:31 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

Playing the devil advocate here only because I find this interesting and I'm 
not advocating anything. Heck I'm probably just arguing for argument sake. 

 If all cables are not equal as Ghery and note and the designer/manufacturer 
has knowledge of that don't the cables then become special accessories in their 
own right? Under 15.27 c) They would not normally be considered special 
accessory items  under the definition because they can be easily purchased at a 
multitude of locations.
15.27 c) Accessory items that can be readily obtained from multiple 
retail outlets are NOT (my emphasis)  considered to be special accessories ...  
But given the knowledge of the designer/manufacturer that cables vary in 
performance and not all cables were tested the only assurance they have that 
the system will perform as intended is buy telling the consumer exactly which 
cable they must use buy name and brand. But if they do that then the cable 
isn't readily obtained from multiple outlets and is now by definition a 
special accessory. Paragraph 15.27 says that The party responsible for the 
equipment, as detailed in §2.909 of this chapter, shall ensure that these 
special accessories are provided with the equipment So now must the cable be 
provided?


Gmac

-Original Message-
From: Pettit, Ghery [mailto:ghery.pet...@intel.com]
Sent: Thursday, September 04, 2014 12:46 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables

You are highly unlikely to find the ferrite prayer beads at Best Buy.  If you 
don't specify which ones to get you have no idea what the result will be.  I 
think you are correct, the beads must be shipped with the product.  The right 
ones, to boot.

Now, how does the designer know that he needs ferrite beads?  My experience has 
been that many (most?) HDMI cables do not have their shields terminated 
properly, if at all.  Once the shields are terminated correctly problems go 
away.  Could this be a better solution?

Ghery S. Pettit

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
emc-p...@ieee.org

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http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
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For help, send mail to the list administrators:
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-

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