[RFI] RFI Digest, Vol 268, Issue 7
Kenneth Wyatt
wyattphoto at mac.com
Fri May 23 17:22:21 EDT 2025
Group,
HDMI cable quality varies quite a lot. I wrote an article on HDMI cable EMI in 2017 during the time I served as senior technical editor for Interference Technology Magazine. Looking at the HDMI web site today (https://www.hdmi.org <https://www.hdmi.org/>), I see they are announcing the version 2.2 of the standard coming soon. Unfortunately, you have to be an “HDMI Adopter” to get access to any of their standards.
The current 2.1b version is described as (with no hint as to whether the shield bonding has been addressed):
The HDMI Forum has published Version 2.1b of the HDMI® Specification which is available to HDMI 2.x Adopters. This includes a general clean up, clarifications to improve interoperability, and incorporation of errata. Please refer to the 2.1b Specification page.
I also gather from their home page that there are companies that are counterfeiting (surprise!) HDMI cables and so are “unlicensed”. That likely means that they may be taking shortcuts in properly terminating the cable shield. The best bet today, accounting for HDMI clones, is to stick with major brand names for minimized RFI.
Here is the link to my original article: https://interferencetechnology.com/hdmi-cables-emi/ <https://interferencetechnology.com/hdmi-cables-emi/>
I interviewed the HDMI Licensing Administrator, Brad Bramy for the article, and the response at the time was evasive in specific detail, but at least they admitted to knowing concerns with the cable specifications.
Here’s a link to Bergey and Altland’s paper from DesignCon 2008, where they test a variety of consumer cables for shielding performance, including HDMI.
https://www.magazines007.com/pdf/DC08_Dana_Bergey.pdf <https://www.magazines007.com/pdf/DC08_Dana_Bergey.pdf>
For those curious as to how bad pigtailed shield connections can be, take a look at this demo video I made: https://www.youtube.com/watch?v=XoLBOuLH8t0&t=1s <https://www.youtube.com/watch?v=XoLBOuLH8t0&t=1s>
More EMC demo videos here (Ha!): http://www.emc-seminars.com/page11/Videos.html <http://www.emc-seminars.com/page11/Videos.html>
Cheers, Ken
______________________
Kenneth Wyatt
wyattphoto at mac.com
> On May 23, 2025, at 10:00 AM, rfi-request at contesting.com wrote:
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> Today's Topics:
>
> 1. Re: RFI on New Digital TV (Jim McCook)
> 2. Re: RFI on New Digital TV (Jim Brown)
> 3. Re: RFI on New Digital TV (David Eckhardt)
> 4. Re: RFI on New Digital TV (Jim McCook)
> 5. Re: RFI on New Digital TV (Jim Brown)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 22 May 2025 21:00:22 +0000
> From: Jim McCook <w6ya at cox.net>
> To: RFI List <rfi at contesting.com>
> Subject: Re: [RFI] RFI on New Digital TV
> Message-ID: <3076a7ff-923e-4682-8c86-b8a27982c858 at cox.net>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> For now the RFI on the new digital LG TV has been stopped.? The solution
> was a type 31 one inch ID snap-on toroid with 4 turns on EACH end of the
> 25' HDMI cable between the new digital receiver and the TV.? One toroid
> on either end was not sufficient.? None of this was necessary with the
> previous units, which were android units.? The same cables were used in
> the new installation.? None of the receiver peripherals were changed.?
> All speaker leads had previously been wrapped on 1-5/8 ID type 31
> toroids.? I still wish I had the old android units.? 73, Jim
>
> ------------------------------
>
> Message: 2
> Date: Thu, 22 May 2025 14:12:04 -0700
> From: Jim Brown <jim at audiosystemsgroup.com>
> To: rfi at contesting.com
> Subject: Re: [RFI] RFI on New Digital TV
> Message-ID:
> <320da74c-4e72-4d77-b52c-ef6f4f0b5033 at audiosystemsgroup.com>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> Thanks for the feedback, Jim. I'm not surprised that both ends were
> needed. Suggests either a common mode problem on both ends or that it
> simply needed another 6dB of choking.
>
> 73, Jim K9YC
>
> On 5/22/2025 2:00 PM, Jim McCook wrote:
>> For now the RFI on the new digital LG TV has been stopped.? The solution
>> was a type 31 one inch ID snap-on toroid with 4 turns on EACH end of the
>> 25' HDMI cable between the new digital receiver and the TV.? One toroid
>> on either end was not sufficient.? None of this was necessary with the
>> previous units, which were android units.? The same cables were used in
>> the new installation.? None of the receiver peripherals were changed.
>> All speaker leads had previously been wrapped on 1-5/8 ID type 31
>> toroids.? I still wish I had the old android units.? 73, Jim
>> _______________________________________________
>> RFI mailing list
>> RFI at contesting.com
>> http://lists.contesting.com/mailman/listinfo/rfi
>
>
>
>
> ------------------------------
>
> Message: 3
> Date: Thu, 22 May 2025 21:47:37 +0000
> From: David Eckhardt <davearea51a at gmail.com>
> To: Jim McCook <w6ya at cox.net>
> Cc: RFI List <rfi at contesting.com>
> Subject: Re: [RFI] RFI on New Digital TV
> Message-ID:
> <CAODdWWEsQWgx8EWjqW28yUGa362Sh_U4zL0WMMv27cB05WBVkw at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> In my experience, HDMI is a very dirty interface. It takes a well
> constructed and shielded HDMI to contain the RFI. In addition, it also
> requires a good RF termination of the shield. Jumper wires don't get the
> job done!
>
> Dave - W?LEV
>
> On Thu, May 22, 2025 at 9:22?PM Jim McCook <w6ya at cox.net> wrote:
>
>> For now the RFI on the new digital LG TV has been stopped. The solution
>> was a type 31 one inch ID snap-on toroid with 4 turns on EACH end of the
>> 25' HDMI cable between the new digital receiver and the TV. One toroid
>> on either end was not sufficient. None of this was necessary with the
>> previous units, which were android units. The same cables were used in
>> the new installation. None of the receiver peripherals were changed.
>> All speaker leads had previously been wrapped on 1-5/8 ID type 31
>> toroids. I still wish I had the old android units. 73, Jim
>> _______________________________________________
>> RFI mailing list
>> RFI at contesting.com
>> http://lists.contesting.com/mailman/listinfo/rfi
>>
>
>
> --
>
> *Dave - W?LEV*
>
>
> ------------------------------
>
> Message: 4
> Date: Thu, 22 May 2025 22:16:02 +0000
> From: Jim McCook <w6ya at cox.net>
> To: RFI List <rfi at contesting.com>
> Subject: Re: [RFI] RFI on New Digital TV
> Message-ID: <a3788bed-c0cb-43e7-8186-c674ab4b9d6f at cox.net>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> Jim and Dave... thanks for the input.? It's also interesting to me that
> both ends were needed, since I previously tried two of those huge
> toroids in series on a longer HDMI section at the TV end.? Maybe the
> source of the problem was both at the receiver and in the long 25' HDMI
> cable.? I know that length is way too long, but I have no choice because
> the console with receiver and peripherals is built in and that far away,
> with the TV on a wall mounted swivel.? That cable was picked by our IT
> guy and he used a good one.
>
> BTW our equipment is built into a console that is a peninsula extending
> a few feet out from the LR wall.? It has front and back doors, so access
> to the back of everything is easy, making life a lot easier.?? Wireless
> headsets are helpful if my XYL wants to read while I watch TV. ? Jim W6YA
>
>
>
> ------------------------------
>
> Message: 5
> Date: Thu, 22 May 2025 15:17:11 -0700
> From: Jim Brown <jim at audiosystemsgroup.com>
> To: rfi at contesting.com
> Subject: Re: [RFI] RFI on New Digital TV
> Message-ID:
> <92bf4e6d-54ec-41b2-8253-40883888d2a1 at audiosystemsgroup.com>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> On 5/22/2025 2:47 PM, David Eckhardt wrote:
>> It takes a well
>> constructed and shielded HDMI to contain the RFI.
>
> I don't know anything about that format. Is it balanced or unbalanced?
> I'm assuming matched. Are you aware of sources for well-built cables?
>
> 73, Jim K9YC
>
>
>
> ------------------------------
>
> Subject: Digest Footer
>
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> ------------------------------
>
> End of RFI Digest, Vol 268, Issue 7
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