Just a comment about the prospective "load impedance" issue mentioned. It
has been my experience that the utility power system for the house has a
much lower source impedance than any portable inverter.
I've had occasion to test such with commercial 1 KVA to 7 KVA double
conversion UPS's made by Staco, Powerware, Triplite and Best. The UPS's all
revealed a higher output impedance than the utility power.
I would conclude any RFI coming back to the AC supply would be noticeably
worse with an inverter or UPS that it would be with the utility source.
Ray, W4BYG
"The Republic can survive a fool for a president... It is less likely to
survive a multitude of fools, such as those who made him their president."
-----Original Message-----
From: RFI [mailto:rfi-bounces@contesting.com] On Behalf Of Tom Thompson
Sent: Wednesday, March 26, 2014 8:44 PM
To: Don Kirk
Cc: Dale J.; Hare, Ed W1RFI; rfi@contesting.com Reflector
Subject: Re: [RFI] ARRL to FCC...
Hi Don,
Thanks for the information. Those common mode chokes certainly are
effective. Your experience would suggest that it is not just radiation
emitting from the front of the screen that causes the RFI. Since common
mode choking is a function of both the source and the load impedance, it
would be interesting to isolate the TV from the house wiring completely by
running the TV on a battery/inverter in order to completely isolate it
electrically from the house wiring.
Your average tracking time of 10 minutes illustrates that with a little
practice finding the RFI source is the lesser problem. Fixing it is another
matter. Your youtube video certainly shows this.
Good documentation!
73, Tom W0IVJ
On 3/26/2014 6:00 PM, Don Kirk wrote:
> Hi Tom,
>
> I'm the one that reported the 3 Samsung Plasma TV cases to Ed and the
> ARRL, and in all cases the common mode chokes were the same (14 turns
> of a power cord on a 2.4" OD Fair-Rite #31 mix toroid core), and you
> can see my most successful case on youtube at
> http://sites.google.com/site/televisionrfi/
>
> My average time for tracking down a Plasma TV generating RFI is about
> 10 minutes, but my most recent case has also been the most difficult.
>
> Here is the info I sent to Ed that he just mentioned which provides
> more details :
> ------------------------------------------------
> I worked on 3 Plasma TVs generating RFI within the last year, and the
> results have covered the entire spectrum so to speak. In one case 14
> turns of the TV power cord thru #31 toroid core did a great job, in
> the second case 14 turns of the TV power cord reduced the signal
> somewhat, and in the 3rd case the toroid core on the power cord, as
> well as a Delta EMI line filter (10DRCG5) had no impact (and
> disconnecting all other cables from the TV had no impact).
>
> All 3 Plasma TVs have been Samsung. The 3rd case mentioned above (the
> one in which nothing worked) is 930 feet from my house and it's
> located below grade (in a basement below ground). I have discussed
> this specific case with the ARRL.
>
> The model number of the 3rd case mentioned above is is as follows :
> Model : PN58B650S1FXZA
> Serial : AUQ53CE5400478F
> Version : K301
>
> I personally am concerned that radiation from the screen (or other
> parts of the TV) may be coupling back into house wiring, etc. and that
> filtering at the TV (line cord, etc.) may not totally mitigate the RFI.
> ------------------------------------
> 73,
> Don (wd8dsb)
>
>
>
>
> On Wed, Mar 26, 2014 at 5:24 PM, Tom Thompson <tlthompson@qwest.net
> <mailto:tlthompson@qwest.net>> wrote:
>
> Ed,
>
> As you well know, all common mode chokes are not created equally.
> Do you have any details on the chokes that did and did not work?
>
> Tom W0IVJ
>
>
> On 3/26/2014 1:29 PM, Hare, Ed W1RFI wrote:
>
> One report I received back indicated that one plasma TV was
> cured with common-mode chokes, but two other models were not.
> All were Samsung products.
>
> -----Original Message-----
> From: RFI [mailto:rfi-bounces@contesting.com
> <mailto:rfi-bounces@contesting.com>] On Behalf Of Dale J.
> Sent: Wednesday, March 26, 2014 2:44 PM
> To: Tom Thompson
> Cc: rfi@contesting.com <mailto:rfi@contesting.com> Reflector
> Subject: Re: [RFI] ARRL to FCC...
>
> Tom,
>
> I'd love to do a lot of stuff with their tv, but it's not my
> house and I hate to impose on them. I have to catch the
> neighbor outside on a weekend and chat with him a little and
> maybe something might get going. As you can see I'm a little
> squeamish about imposing on other people's home and property.
> I guess I wouldn't like it much and therein lies my problem,
> hi. But I'll work on it. Maybe by the time I finally can do
> some real investigation the TV will die.
>
> Dale, k9vuj
>
>
>
> On 26, Mar 2014, at 13:18, Tom Thompson <tlthompson@qwest.net
> <mailto:tlthompson@qwest.net>> wrote:
>
> Dale,
>
> I checked with Costco and they only carry LED back lit TV
> sets now. In thinking about it further, I don't think
> making a measurement on the power cord with an RF current
> probe would be too definitive anyway because of the RFI
> coming from the other sets connected on the same circuit.
> It would be instructive if you could conduct some tests
> on your neighbor's set. Would it be possible to use a
> battery and quiet inverter to power the set with all other
> wires disconnected? You might have to connect the cable
> to get the screen to light. If you could do that and it
> eliminated the RFI then the line filters Ed suggested
> might work for you.
>
> Just some thoughts.
>
> Tom W0IVJ
>
> On 3/26/2014 2:23 AM, Dale J. wrote:
>
> My next door plasma is broadband hash with various
> bumps along the way. I have one of those bumps
> especially bad at 3.857, it's 20 db over 9 and sounds
> like a motor running but changing speed and sometimes
> stopping and starting. The broadband hash is all over
> the 80 meter band and 40 too. The upper bands are
> less affected. I suspect part of the noise is from a
> switching power supply in the plasma tv, that might be
> what that motor sounding noise is not sure though. I
> wish it were my TV, I could then find out more how
> these things tick before permanently disabling it.
> Makes it difficult on my USAF MARS net too.
>
> Dale, k9vuj
>
>
>
> On 25, Mar 2014, at 21:16, David Cole <dave@nk7z.net
> <mailto:dave@nk7z.net>> wrote:
>
> Imagine thousands of little lightening bolts...
> Thats Plasma TV.
> --
> Thanks and 73's,
> For equipment, and software setups and reviews see:
> www.nk7z.net <http://www.nk7z.net>
> for MixW support see;
> http://groups.yahoo.com/neo/groups/mixw/info
> for Dopplergram information see:
> http://groups.yahoo.com/neo/groups/dopplergram/info
> for MM-SSTV see:
> http://groups.yahoo.com/neo/groups/MM-SSTV/info
>
>
> On Tue, 2014-03-25 at 18:28 -0600, Tom Thompson wrote:
>
> Ed,
>
> I checked out a few plasma tv sets a couple of
> years ago with a
> portable shortwave receiver. The RFI was
> coming right out of the
> front of the set which made sense since that
> was where the discharge was occurring.
>
> Tom W0IVJ
>
> On 3/25/2014 12:31 PM, Hare, Ed W1RFI wrote:
>
> Thanks, Dale.
>
> We can then see if the TV is still in
> production. If it is no longer
> manufacturered, it may be a harmful
> interference complaint, not a possible
> emissions-limit violation.
>
> The ARRL Lab would also be willing to
> provide a few filters to try, if your
> neighbor is willing to work with you.
> Some have speculated that the noise comes
> directly from the TV, and this could be
> true, but I still tend to think in terms
> of noise coming out the AC mains and
> possibly also being radiated by the shield
> of the incoming coaxial feed line.
>
> -----Original Message-----
> From: Dale J. [mailto:dj2001x@comcast.net
> <mailto:dj2001x@comcast.net>]
> Sent: Tuesday, March 25, 2014 2:29 PM
> To: Hare, Ed W1RFI
> Cc: rfi@contesting.com
> <mailto:rfi@contesting.com>
> Subject: Re: [RFI] ARRL to FCC...
>
> Ed
>
> I'll see if I can get that information
> from my neighbor, but it will take a
> while. I have to actually get in the
> house and look at the back of the TV and
> get the model number because I don't think
> they know for sure. As soon as I get it
> I'll send you a email.
>
> Tnx
> 73
> Dale, K9VUJ
>
>
> On 25, Mar 2014, at 13:04, "Hare, Ed
> W1RFI" <w1rfi@arrl.org
> <mailto:w1rfi@arrl.org>> wrote:
>
> If the ARRL Lab can get some reports
> involving specific model numbers, we
> can do some testing and find out where
> these plasma sets stand. I had a
> report in MD that involved two Samsung
> plasma TVs. One made very loud
> radiated noise, while the 2nd model,
> also a plasma TV, was quiet.
>
> I need reports that involve a plasma
> TV operating in a neighbor's home
> causing harmful interference. So far,
> most of the reports have been about
> the QRZ.com and RFI list discussions,
> not a specific report.
>
> The ARRL Lab can measure conducted
> noise and radiated noise from devices,
> but we really need to start with
> actual, non-general reports.
>
> Ed Hare, W1RFI
> ARRL Lab
>
> -----Original Message-----
> From: RFI
> [mailto:rfi-bounces@contesting.com
> <mailto:rfi-bounces@contesting.com>]
> On Behalf Of KD7JYK
> DM09
> Sent: Friday, March 21, 2014 12:23 AM
> To: rfi@contesting.com
> <mailto:rfi@contesting.com>
> Subject: Re: [RFI] ARRL to FCC...
>
> : Now if they would recall all the
> damn plasma TV's out there
> doing the same
> : thing it would really tickle my butt
> cheeks...but, any such
> action is
> : goodness!
>
> How mant times have you contacted the
> FCC regarding the interference to your
> licensed service?
>
> Kurt
>
>
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