Interference between HDMI and RF leads - advice requested

Update today

I found a single clip-on ferrite core and tried that at each end with
no effect. I then tried Bill's suggestion of another TV. I used an
earlier Sony Bravia that also had an HDMI port and this worked
perfectly.

Suspecting now that the problem is with the HDMI circuitry in the TV
rather than the Recorder I have now contacted the Sony Centre where I
bought the TV. Tomorrow I am going to take the TV and Recorder to the
Centre for them to test.

It won't help that I have a Panasonic Recorder that I want to work
with a Sony TV but I feel ceratin that these things are designed to
work together. The staff at the Sony Centre claim never to have had a
problem with HDMI but...... Further updates in due course.

In message , Brian Gaff
wrote

CPC have the ferrites,

http://cpc.farnell.com/jsp/level5/module.jsp?moduleId=cpc/431138.xml

--
Alan
news2009 {at} admac {dot} myzen {dot} co {dot} uk

On Tue, 31 Aug 2010 13:44:52 +0100, ChrisW
wrote:

Update today

I found a single clip-on ferrite core and tried that at each end with
no effect. I then tried Bill's suggestion of another TV. I used an
earlier Sony Bravia that also had an HDMI port and this worked
perfectly.

Suspecting now that the problem is with the HDMI circuitry in the TV
rather than the Recorder I have now contacted the Sony Centre where I
bought the TV. Tomorrow I am going to take the TV and Recorder to the
Centre for them to test.

It won't help that I have a Panasonic Recorder that I want to work
with a Sony TV but I feel certain that these things are designed to
work together. The staff at the Sony Centre claim never to have had a
problem with HDMI but...... Further updates in due course.

This is to report that my new Recorder and TV worked perfectly in the
Sony Centre in Perth. I put this down to the fact that Perth uses a
relay transmitter with different frequencies to my local Angus
transmitter.

I then bought some more HDMI cables. The Panasonic one I bought has
eliminated the problem completely at home. There does seem to be a
problem with some fequencies upsetting the DVD Recorder tuners when
some types of HDMI lead are connected. I now have 4 leads. Two work
fine and two do not yet all claim to meet the required HDMI
specification. Clearly not all HDMI leads are created equal and
paying a lot does not guarantee success.

On Sep 7, 5:59*pm, ChrisW wrote:
On Tue, 31 Aug 2010 13:44:52 +0100, ChrisW





wrote:
Update today

I found a single clip-on ferrite core and tried that at each end with
no effect. *I then tried Bill's suggestion of another TV. *I used an
earlier Sony Bravia that also had an HDMI port and this worked
perfectly. *

Suspecting now that the problem is with the HDMI circuitry in the TV
rather than the Recorder I have now contacted the Sony Centre where I
bought the TV. *Tomorrow I am going to take the TV and Recorder to the
Centre for them to test. *

It won't help that I have a Panasonic Recorder that I want to work
with a Sony TV but I feel certain that these things are designed to
work together. *The staff at the Sony Centre claim never to have had a
problem with HDMI but...... * * Further updates in due course.

This is to report that my new Recorder and TV worked perfectly in the
Sony Centre in Perth. *I put this down to the fact that Perth uses a
relay transmitter with different frequencies to my local Angus
transmitter.

I then bought some more HDMI cables. *The Panasonic one I bought has
eliminated the problem completely at home. *There does seem to be a
problem with some fequencies upsetting the DVD Recorder tuners when
some types of HDMI lead are connected. *I now have 4 leads. *Two work
fine and two do not yet all claim to meet the required HDMI
specification. *Clearly not all HDMI leads are created equal and
paying a lot does not guarantee success. *- Hide quoted text -

- Show quoted text -

I must say that you have had problems completely outside my
experience, and I think that of most others here. Clearly there are
oddities with HDMI which although they are rare are worth knowing
about.

Bill

At 17:59:53 Tue, 7 Sep 2010, ChrisW
wrote in article :
[..]
I then bought some more HDMI cables. The Panasonic one I bought has
eliminated the problem completely at home. There does seem to be a
problem with some fequencies upsetting the DVD Recorder tuners when
some types of HDMI lead are connected. I now have 4 leads. Two work
fine and two do not yet all claim to meet the required HDMI
specification. Clearly not all HDMI leads are created equal and
paying a lot does not guarantee success.

Are all the leads the same length ?

--
John L

On Wed, 8 Sep 2010 12:45:32 +0100, John Legon
wrote:

At 17:59:53 Tue, 7 Sep 2010, ChrisW
wrote in article :
[..]
I then bought some more HDMI cables. The Panasonic one I bought has
eliminated the problem completely at home. There does seem to be a
problem with some fequencies upsetting the DVD Recorder tuners when
some types of HDMI lead are connected. I now have 4 leads. Two work
fine and two do not yet all claim to meet the required HDMI
specification. Clearly not all HDMI leads are created equal and
paying a lot does not guarantee success.

Are all the leads the same length ?

No they are not. The two leads that work are both 1.5m whereas the
two that don't are 1.2m and 1.3m.

At 20:43:52 Thu, 9 Sep 2010, ChrisW
wrote:
On Wed, 8 Sep 2010 12:45:32 +0100, John Legon
wrote:

At 17:59:53 Tue, 7 Sep 2010, ChrisW
wrote in article :
[..]
I then bought some more HDMI cables. The Panasonic one I bought has
eliminated the problem completely at home. There does seem to be a
problem with some fequencies upsetting the DVD Recorder tuners when
some types of HDMI lead are connected. I now have 4 leads. Two work
fine and two do not yet all claim to meet the required HDMI
specification. Clearly not all HDMI leads are created equal and
paying a lot does not guarantee success.

Are all the leads the same length ?

No they are not. The two leads that work are both 1.5m whereas the
two that don't are 1.2m and 1.3m.

This does seem to suggest that harmonics or frequency components in the
HDMI signal are causing the shorter leads to resonate and radiate RF in
the part of the UHF band that your tuners are tuned to, while the two
longer leads are tuned to a different frequency.

The difference in length between the working and non-working leads would
be roughly half a wavelength...

--
John Legon

In message , John Legon
writes
At 20:43:52 Thu, 9 Sep 2010, ChrisW
wrote:
On Wed, 8 Sep 2010 12:45:32 +0100, John Legon
wrote:

At 17:59:53 Tue, 7 Sep 2010, ChrisW
wrote in article :
[..]
I then bought some more HDMI cables. The Panasonic one I bought has
eliminated the problem completely at home. There does seem to be a
problem with some fequencies upsetting the DVD Recorder tuners when
some types of HDMI lead are connected. I now have 4 leads. Two work
fine and two do not yet all claim to meet the required HDMI
specification. Clearly not all HDMI leads are created equal and
paying a lot does not guarantee success.

Are all the leads the same length ?

No they are not. The two leads that work are both 1.5m whereas the
two that don't are 1.2m and 1.3m.

This does seem to suggest that harmonics or frequency components in the
HDMI signal are causing the shorter leads to resonate and radiate RF in
the part of the UHF band that your tuners are tuned to, while the two
longer leads are tuned to a different frequency.

The difference in length between the working and non-working leads would
be roughly half a wavelength...

Of course, it could be that something is going into oscillation
(possibly due to a fault condition, rather than a design fault). This
could depend on lead length.
--
Ian