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Topic # 119036 17-May-2013 22:01
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Well as the title suggests my newly bought Netcomm Ethernet over Power Adapters interfere with my Freeview TV signal. (I mean total loss of TV signal)

The only thing I can think of is that my UHF aerial has a masthead amplifier which uses a 9v power injector to power the amplifier on the aerial mast.

The moment I unplug either of the two Netcomm adapters (different sides of the house) the TV signal is restored. 

Has anyone ever seen this before? and have you solved it?


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  Reply # 821423 17-May-2013 23:38
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It wouldn't surprise me that this happens if you are living in an area where the UHF signal is a bit weak (the presence of a masthead amp generally means that is the case).  All the mains wiring in your house is acting as a giant antenna, radiating harmonics from the data signal, which are obliterating the DTT signals.

As I see it, you have 3 options, probably none of them that you want to hear:

1)  Run some CAT5/6 and ditch the Netcomm Ethernet over power adaptors
2)  Run a couple of "N" WiFi access points as a bridge, and also ditch the Ethernet over power adaptors
3)  Switch to satellite for your TV viewing







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  Reply # 821481 18-May-2013 09:58
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grant_k: It wouldn't surprise me that this happens if you are living in an area where the UHF signal is a bit weak (the presence of a masthead amp generally means that is the case).  All the mains wiring in your house is acting as a giant antenna, radiating harmonics from the data signal, which are obliterating the DTT signals.

As I see it, you have 3 options, probably none of them that you want to hear:

1)  Run some CAT5/6 and ditch the Netcomm Ethernet over power adaptors
2)  Run a couple of "N" WiFi access points as a bridge, and also ditch the Ethernet over power adaptors
3)  Switch to satellite for your TV viewing


Was really trying to avoid going under the house to run more Cat5, just to get under there I have to break/remove cladding or deconstruct a section of deck. My only reason for having them was to move my modem to another jack point, while keeping my w/less router where it is. The master jackpoint has a lower sync rate than one on the far end of the house, even though it piggy backs off the master jack point!

Perhaps I can just throw a resistor on the line to simulate the extra cable length. The roadside cabinet in outside the neighbours house so might actually be too close.

I have a dish on the roof..... don't want to pay sky and don't like SD free view. Only really watch Huluplus these days so its just more annoying than anything else

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  Reply # 821533 18-May-2013 11:28
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I wonder if the aerial and/or amplifier needs a better earth or something?

I would suggest that if your modem is already in the master jack, then why not just fix the jack? Put in a master filter while you are at it, so you are effectively bypassing the phone jacks for ADSL with a new RJ45 jack next to it thats dedicated (and labled for) ADSL with the filter in behind the wall.

I could help out if you are in Auckland, not too much other work on at moment.




Qualified in business, certified in fibre, stuck in copper, have to keep going  ^_^

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  Reply # 821545 18-May-2013 11:43
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It does sound suspiciously like an earth issue with the aerial system. How old is the aerial / who installed it?

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  Reply # 821562 18-May-2013 12:40
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Those ethernet over power boxes really do spew out massive RF noise when in operation.

Probably they are making so much in the lower VHF band where the mast head amp will still have a lot of gain, despite being useless these days that it is just causing intermodulation over everything on the output.

Most power supplies for masthead amps are just a basic transformer, so will nicely couple all the noise from the ethernet over power box onto the coax where it will screw with the amp.

I would suggest lose the amp unless you specifically needed it put in for the digital tv, since there are so many that were put in for analog UHF which are redundant on digital.

See if you have problems powering the masthead amp off a UPS or something. If that solves it see if there is a newer wall wart available for them which will presumably have filtering on it.




Richard rich.ms



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  Reply # 821615 18-May-2013 14:17
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richms: Those ethernet over power boxes really do spew out massive RF noise when in operation.

Probably they are making so much in the lower VHF band where the mast head amp will still have a lot of gain, despite being useless these days that it is just causing intermodulation over everything on the output.

Most power supplies for masthead amps are just a basic transformer, so will nicely couple all the noise from the ethernet over power box onto the coax where it will screw with the amp.

I would suggest lose the amp unless you specifically needed it put in for the digital tv, since there are so many that were put in for analog UHF which are redundant on digital.

See if you have problems powering the masthead amp off a UPS or something. If that solves it see if there is a newer wall wart available for them which will presumably have filtering on it.


I live close to Albany village so I really do need the masthead amp, without it there is zero signal. Even with the AMP the signal strength was marginal when the installer used his digital meter. It was only put in several months back as the previous owner used the SKY dish.

Sadly a UPS would be getting a little serious as noting else of worth is close by, but that does sound like a great idea so might have to try it. Just want to avoid spending more money after bad.

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