OTA Signal Strength Fluctuates on New TV

[shoe]

Hello,

I just bought a new Samsung TV and connected my antenna to it. Immediately, I noticed the reception flickered every couple of seconds. When I view the signal strength on the TV, it fluctuates from a full signal to a half signal regularly causing the flickering. The same antenna connected another TV has no issues.

Should I assume it's the tuner on the TV? I've tried 3 different coax cables with the same result.

Any help is appreciated.

Thanks!

[ADTech]

Wildly fluctuating signal strength/quality swings is almost always one of the following:

1. Multi-path interference, usually moving trees.
2. Electrical or electronic interference, most commonly FM radio or power line nose, both on VHF channels.
3. Signal power at the edge of the "digital cliff".
4. Over amplification.

Different tuners have different capabilities in dealing with such signal impairments. Some handle it will well, others do not.

If you just added a splitter, then you may also need to consider either that the splitter is bad (swap ports) or the additional signal insertion loss of the splitter plus the coax leaves an inadequate amount of signal for the tuner.

Try swapping the TV sets and see if the issue stays with the set or if it stays with that drop location.

[Billiam]

Originally Posted by shoe

Hello,

I just bought a new Samsung TV and connected my antenna to it. Immediately, I noticed the reception flickered every couple of seconds. When I view the signal strength on the TV, it fluctuates from a full signal to a half signal regularly causing the flickering. The same antenna connected another TV has no issues.

Should I assume it's the tuner on the TV? I've tried 3 different coax cables with the same result.

Any help is appreciated.

Thanks!

What brand is the other TV? Is it still a relatively new HDTV?

[shoe]

Thanks for the help.

Both TVs are Samsungs. The one that works fine is about 5 years old and the drop is actually further from the antenna than where the new one is.

Next, I'm going to try the new one at the same exact location as the one that's working and see what happens. If it still does it, I can narrow it down to the TV. If it is the TV, could a replacement of the same model fix the issue? Or, will it likely have the same issue?

[rabbit73]

Welcome to the forum, shoe:

Guidelines when asking for help
http://forum.tvfool.com/showthread.php?t=4

Please post your tvfool report using your exact address (which will not show) so that we can see what your signals look like using this:
http://www.tvfool.com/index.php?opti...pper&Itemid=29

Next, I'm going to try the new one at the same exact location as the one that's working and see what happens.

good idea

Does the flickering happen on all channels, or just certain channels?

What antenna are using and where is it located, inside or outside?

Are you using a preamp? If yes, what model?

Are there any trees or buildings in the signal path?

Where are you located?

Should I assume it's the tuner on the TV?

If it still does it, I can narrow it down to the TV.

It's too early to tell.

If it is the TV, could a replacement of the same model fix the issue? Or, will it likely have the same issue?

The performance of tuners can vary from brand to brand, and even from model to model within the same brand. But, the performance of tuners for the same model should be similar. If not, the tuner is defective.

When I test tuners I use a splitter to feed both tuners at the same time to get a real-time comparison. The strength of OTA signals is constantly changing, so removing the coax from one TV and connecting it to the other isn't the most accurate way, but it is good enough for your present test.

To make an accurate comparison I insert a variable attenuator before the splitter and make the signal progressively weaker to see which TV drops out the signal last:

                                                    TV 1
                                                  /
antenna > coax > variable attenuator > splitter > 
                                                  \
                                                    TV 2

[shoe]

Thanks again.

My Report is HERE.

Does the flickering happen on all channels, or just certain channels?

What antenna are using and where is it located, inside or outside?

Are you using a preamp? If yes, what model?

Are there any trees or buildings in the signal path?

Where are you located?

It appears to be all channels, but I haven't gone through all of them to verify that yet.

I'm using a Terk HDTVa that has a built in amplifier that is located in my attic. Other than my roof, there is nothing in the way of the signal.

I'm in Bel Air, MD.

The performance of tuners can vary from brand to brand, and even from model to model within the same brand. But, the performance of tuners for the same model should be similar. If not, the tuner is defective.

When I test tuners I use a splitter to feed both tuners at the same time to get a real-time comparison. The strength of OTA signals is constantly changing, so removing the coax from one TV and connecting it to the other isn't the most accurate way, but it is good enough for your present test.

To make an accurate comparison I insert a variable attenuator before the splitter and make the signal progressively weaker to see which TV drops out the signal last:

I don't have a variable attenuator, but I hope to have more information later once I test the new TV from the same drop as older TV that works fine. If it works fine at the new location, I've got some more investigating to do about the other location. If not, it sounds like I have to decide to try the same model again hoping that this tuner is defective or get a new TV altogether.

[rabbit73]

Thanks for the report; it's helpful.

In what direction is the Terk aimed? You have channels in many directions, and the best reception is when the antenna is aimed at the transmitter.

You have many strong signals, the best ones from Baltimore at 246 degrees magnetic. The signal attenuation caused by the attic location is difficult to predict, but I think the amp in your Terk is being overloaded, or the tuner is being overloaded, or both. I would not have suggested an amp, just a good antenna in the attic, like the Winegard HD7694P or the Antennas Direct C2V.

Your strongest signal, WMAR has a Noise Margin of 59.4 dB.



Interpreting Noise Margin in the TV Fool Report
http://www.aa6g.org/DTV/Reception/tvfool_nm.html

I did an FM FOOL report for your estimated location, and it doesn't look like they would interfere with your TV reception. See Attachment No. 2. If I'm wrong, you could add an FM trap/filter later.

[shoe]

In what direction is the Terk aimed? You have channels in many directions, and the best reception is when the antenna is aimed at the transmitter.

The Terk is pointed NW because the reason I got the antenna was to get WPMT and watch Eagles games. So, the antenna is serving its purpose.

I added a TV to my gym and didn't want to get another cable box so I got a Chromecast and connected the antenna to it expecting it would work fine since the other TVs in the house haven't had a problem with it. I'm surprised that the brand new Samsung TV can't handle the signal as well as other, older TVs.

You have many strong signals, the best ones from Baltimore at 246 degrees magnetic. The signal attenuation caused by the attic location is difficult to predict, but I think the amp in your Terk is being overloaded, or the tuner is being overloaded, or both. I would not have suggested an amp, just a good antenna in the attic, like the Winegard HD7694P or the Antennas Direct C2V.

Is the signal strength fluctuation shown by the TV a symptom of an overloaded amp or tuner? Reading the NM article you posted, could an attenuator potentially help?

[ADTech]

Is the signal strength fluctuation shown by the TV a symptom of an overloaded amp or tuner?

See post #2 above.

[rabbit73]

I added a TV to my gym and didn't want to get another cable box so I got a Chromecast and connected the antenna to it expecting it would work fine since the other TVs in the house haven't had a problem with it. I'm surprised that the brand new Samsung TV can't handle the signal as well as other, older TVs.

Oh, I thought you were connecting the antenna directly to the TV.

The Terk is pointed NW because the reason I got the antenna was to get WPMT and watch Eagles games. So, the antenna is serving its purpose.

WPMT is one of your weaker channels, with co-channel interference, adjacent channel interference, and a 2Edge signal path; not a reliable channel. No broadcast of the games on one of your stronger channels?

Is the signal strength fluctuation shown by the TV a symptom of an overloaded amp or tuner?

That is certainly a possibility. The strong signals mix together and create extra spurious signals within the preamp itself that damage the weaker signals like WPMT. This is called IMD, for Intermodulation Distortion.

Inserting an attenuator is the traditional way to deal with IMD, but you can't insert an attenuator between the antenna itself and the amp, because the amp is internal. You could insert an attenuator between the power injector and the TV to test for tuner overload. If you remove the power to the injector, then the dead amp would act like an internal attenuator of unknown value.
http://www.terk.com/docs/common/HDTVA/HDTVA_OM.pdf

[shoe]

Thanks again! This forum has been extremely helpful. I'm looking forward to getting home and trying out a couple things. Hoping to not have to exchange the TV.

Oh, I thought you were connecting the antenna directly to the TV.

Sorry, I wasn't clear. I am connecting it to directly the TV. I have a Chromecast connected separately for other content like Netflix.

WPMT is one of your weaker channels, with co-channel interference, adjacent channel interference, and a 2Edge signal path; not a reliable channel. No broadcast of the games on one of your stronger channels?

Actually, since moving the antenna to the attic, I've had no issues getting WPMT. When it was sitting next to the TV, it was hit or miss.

That is certainly a possibility. The strong signals mix together and create extra spurious signals within the preamp itself that damage the weaker signals like WPMT. This is called IMD, for Intermodulation Distortion.

Thanks. Could turning the Terk pre-amp off help? Also, maybe collapsing the VHF elements so those signals are weaker?

[rabbit73]

Why don't you try it, and let us know?

And then tell us if you want to do any further experiments.

[ADTech]

I have a Chromecast connected separately for other content like Netflix.

Unplug it and retest. I've had an instances where the Chromecast interfered with reception.

[rabbit73]

Here is another case like yours of too much amp:
http://www.highdefforum.com/local-hd...-days-why.html

I've had an instances where the Chromecast interfered with reception.

Interesting, never would have thought of that.

[Tower Guy]

Originally Posted by ADTech

Unplug it and retest. I've had an instances where the Chromecast interfered with reception.

I've heard that some TV sets can interfere with other sets connected to the same splitter. This can happen even when the set is turned off.

[ADTech]

Yep, I read that article by Charles Rhodes. Pretty weird...

http://www.tvtechnology.com/digital-...signals/272723

[shoe]

Looks like you guys nailed it with the over amplification. I'm crossing my fingers, but turning off the pre-amp on the antenna seems to have done the trick. For now, you saved me from returning my new TV.

Thanks again!

[rabbit73]

Thanks for the good news. Glad we could help