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Author Topic: Dish Network RFI  (Read 7672 times)
AB4D
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« on: May 04, 2013, 12:00:03 PM »

Hi.  A few months ago I began using Dish Network as my satellite TV provider.  Part of the service includes a whole house DVR system that comprises of a master unit (Hopper) and remote units (Joey).  I only have one Joey located in the kitchen.  That Joey is causing interference (white noise) on 80 Meters (S9) using an outside dipole 100 feet away.  I don't remember having that problem until recently.  The interference is only present when the Joey is plugged into the wall wart, leaving the wall wart plugged in the AC socket doesn't cause any interference.

Anyone else using the Dish Network Hopper - Joey DVR?  Any interference? I am trying to determine if this is a wide spread problem or just an isolated incident.  Thanks 73
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K1CJS
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« Reply #1 on: May 05, 2013, 09:05:05 AM »

Those devices work by using RF signalling, and it is a widespread problem.  If substituting another wall wart doesn't help (it may not be noisy when not connected to the unit but will be when it is) call Dish and have them send out a TECHNICIAN, not an INSTALLER.  It IS their responsibility to fix the problem, even if they don't think so.  Just be polite and tell them you're getting interference on your radios.  The 'Hopper' system is still so new that they may be happy to help you out.  If not....  Well, there is always the FCC RFI complaint people you can turn to. 

Sorry I couldn't be of any more help.  73!
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AB4D
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« Reply #2 on: July 27, 2013, 09:40:18 AM »

Hi.  In continuance to this issue. Dish Network sent another "Joey" for me to try, but it did not make any difference.  I did a little experimenting and noticed the interference is about 12 db worse when the 75 ohm coax feed from the Dish and the three connections to the television (L Audio, R Audio, Video) are hooked up.

I am considering trying a high pass filter with a cut off frequency near 54 MHz.  Shielding could be a problem as well.  I can clearly see the circuit board right through the holes in the case.  Anyone else using this system without experiencing interference?

Thanks

73, Jim AB4D
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WX7G
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« Reply #3 on: July 28, 2013, 07:47:16 AM »

A high pass filter will do nothing to fix the problem.

The usual way to tackle this problem is with snap-on ferrite cores placed over the cables. Large aperture cores are needed as you will want to route all of the TV cables (L, R, and video) through a single core or series of cores. For the wall wart power supply the thin DC side cable can be wrapped a few times through a core or cores.

You might want to purchase a couple dozen cores and be generous with them. DX Engineering stocks a suitable core, the DXE-CSB-750P.
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KC7GZC
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« Reply #4 on: July 30, 2013, 10:27:04 AM »

I have the same issue. Dish has never responded to three requests to research the issue and I continue to have S8-9 interference from the Joey Hopper on 80 meters through 15 meters for over a year now. This is very discouraging as I have not found a fix for this issue. It has basically eliminated HF operation from my home QTH. I have wrapped Ferrites around everything I can find. It seems to send the RFI into the whole house electrical wiring. I too would gladly welcome any suggestions also.
73
Joe
KC7GZC
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WX7G
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« Reply #5 on: August 01, 2013, 02:22:39 PM »

Is the RFI noise continuous across the 80 meter band or does it peak at regular intervals (such as 20 or 100 kHz)? If continuous (you did say white noise) I suspect it is digital video in the coax connecting the Hopper to the Joey. If it peaks at regular intervals it may be the Joey wall wart or other DC-DC converters inside the Joey.

Experiments to try:

Disconnect the coax cable at the Hopper but leave it connected at the Joey. If the noise goes away it is not the Joey wall wart or Joey DC-DC converters, it is digital video. To see if the coax is defective (loose connector shell to coax shield for example) the Joey can be moved to the Hopper and connected with a short length of coax.

If the noise continues with the coax disconnected at the Hopper the noise source is probably the Joey wall wart or DC-DC converters. Winding the Joey DC power cord several times through a few type 31 mix ferrite cores should reduce the noise. Another experiment is to substitute a battery for the wall wart. If the wall wart lists 12 VDC as the output a 12 volt battery will power the Joey. I have done this substitution on some devices by cutting the DC cord off an extra wall wart having the same DC plug. Using a battery eliminates the ground connection and provides a quiet power supply.
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AB4D
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« Reply #6 on: August 01, 2013, 04:01:45 PM »

Is the RFI noise continuous across the 80 meter band or does it peak at regular intervals (such as 20 or 100 kHz)? If continuous (you did say white noise) I suspect it is digital video in the coax connecting the Hopper to the Joey. If it peaks at regular intervals it may be the Joey wall wart or other DC-DC converters inside the Joey.

Experiments to try:

Disconnect the coax cable at the Hopper but leave it connected at the Joey. If the noise goes away it is not the Joey wall wart or Joey DC-DC converters, it is digital video. To see if the coax is defective (loose connector shell to coax shield for example) the Joey can be moved to the Hopper and connected with a short length of coax.

If the noise continues with the coax disconnected at the Hopper the noise source is probably the Joey wall wart or DC-DC converters. Winding the Joey DC power cord several times through a few type 31 mix ferrite cores should reduce the noise. Another experiment is to substitute a battery for the wall wart. If the wall wart lists 12 VDC as the output a 12 volt battery will power the Joey. I have done this substitution on some devices by cutting the DC cord off an extra wall wart having the same DC plug. Using a battery eliminates the ground connection and provides a quiet power supply.


The noise is continuous and the intensity is fairly equal across the spectrum.  The interference is there but gets worse when the coax or TV cables are connected. It's there whether it's off or on.  Leaving the wall wart plugged into the wall by itself is quiet.  The only effective cure I've found is to unplug the Joey from the wall wart.

I asked Dish if I could dump the DVR system and replace it with simple channel boxes, they responded, it would be considered an upgrade within the contract period, so I would have to extend my current contract if I went that route. I decided to stick with the unplug method until the contract expires...then goodbye Dish Network.

73
« Last Edit: August 01, 2013, 04:08:27 PM by AB4D » Logged
WX7G
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« Reply #7 on: August 01, 2013, 04:59:24 PM »

Thanks for the great data. Well the Joey is definitely the source, as you knew. I don't know if it is the wall wart, a DC-DC converter in the Joey, or if it is digital circuitry in the Joey. It most certainly was tested and received FCC approval for emissions. However, radiated emissions testing begins at 30 MHz. Conducted emissions does cover the HF range. But, even if a device is compliant to FCC rules it can produce the emissions you are experiencing.

The egress path is common-mode noise current taking a path along the power cord. That causes the Joey chassis to be hot with RF noise and that drives noise current along the coaxial cable shield. Ferrite cores and lots of them are the way to attack this problem.

As to changing your system without incurring new charges you might contact this fellow and show him this eham.net thread.

Daniel.Busa@DISH.com
Daniel Busa
DISH L.L.C.
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WX7G, NARTE certified EMC Engineer
« Last Edit: August 01, 2013, 05:03:01 PM by WX7G » Logged
AB4D
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« Reply #8 on: August 01, 2013, 05:21:19 PM »

WX7G Hi,

Thank you for the information.  Daniel is the guy at Dish I've been emailing about this issue. He hasn't proposed any additional charges. Rather, he is just stating company policy, that a contract extension is required if there is a change in the leased equipment.  I suppose he doesn't have the authority to waive that extension.

73 
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WX7G
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« Reply #9 on: August 02, 2013, 06:51:49 AM »

The unit no doubt is in compliance with FCC testing requirements and so the legal responsibility to reduce the RFI or shut the unit off is on you and not Dish Network.

Are you going to try reducing the RFI?
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AB4D
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« Reply #10 on: August 02, 2013, 07:11:25 AM »

The unit no doubt is in compliance with FCC testing requirements and so the legal responsibility to reduce the RFI or shut the unit off is on you and not Dish Network.

Are you going to try reducing the RFI?

The device that was provided to the FCC for testing may have been in compliance with FCC testing requirements, but I disagree with any conclusion that the device currently in my possession is in compliance with the FCC rules regarding harmful interference. It's causing harmful interference that cannot be resolved, I don't own the device, it is leased. The other poster already tried the ferrite choke method as you suggested without success. What I am going to do you ask; I plan to not use the device and return it to Dish Network when I terminate the service.

73   
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WX7G
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« Reply #11 on: August 02, 2013, 08:38:48 AM »

Let's say your unit produces conducted noise right at the FCC class B limit of 250 uV and that it is entirely common-mode.  The EMC receiver noise bandwidth is 9 kHz. This is the worst-case condition and complies with FCC rules. This 250 uV driving a dipole having an input impedance of 50 ohms resistive causes a radiated power of 1.25 nW. At a distance of 100' a resonant 3.5 MHz receive dipole will drive approximately -63 dBm into a 50 ohm receiver.  This is S-9 + 10 dB. While the coupling mechanism in your case is not dipole-to-dipole this example illustrates the RFI potential of a device that has passed FCC testing. Additionally, the coupling from a device in the home to an antenna can actually be better than this dipole-to-dipole example.




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