# Help With Digital Televison reception.



## btszoch (Nov 2, 2008)

I have a 37" Sony HDTV, the biggest antenna you can buy in my attic (uhf/vhf), a pre-amp hooked up to the antenna, and a 30 dB amplifier hooked up right next to my TV. My TV recognizes digital channels such as 4.1 and 9.1 etc., and I even receive some over-the-air HD channels. But, while watching these digital and HD channels, the reception starts to get out of hand with green squares, other uncharacteristic colors, the sound goes away, and pretty soon the whole screen turns to black with "No Signal." What can I do to consistently receive these digital channels? I know putting the antenna on the roof would probably help, but is there anything else I can do besides that??


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## Old Rich (May 31, 2007)

and welcome to the Forum

How far are you from the transmiting towers?


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## bruiser (Jul 30, 2005)

If you have another tv you can hook up to the antenna when the problem occurs, you can determine if the antenna system is bad or not.


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## magnethead (Mar 18, 2006)

is your antenna aimed the right way?

http://antennaweb.org/aw/welcome.aspx


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## bruiser (Jul 30, 2005)

Try taking the amp out of the circuit and see what happens.


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## DonaldG (Aug 23, 2007)

Not only do you have top be accurate in pointing the antenna in the right direction, It is also very important to have the antenna polarisation correct.

Polarisation, in simple terms , is having the antenna elements either horizontal or vertical. Get it wrong and there will be something like 23 - 26db cross polarisation loss (for every 3db loss, halve the signal.)

Check your neighbours antennas and see which way they are pointing and are the elements horizontal or vertical...


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## magnethead (Mar 18, 2006)

DonaldG said:


> Not only do you have top be accurate in pointing the antenna in the right direction, It is also very important to have the antenna polarisation correct.
> 
> Polarisation, in simple terms , is having the antenna elements either horizontal or vertical. Get it wrong and there will be something like 23 - 26db cross polarisation loss (for every 3db loss, halve the signal.)
> 
> Check your neighbours antennas and see which way they are pointing and are the elements horizontal or vertical...


Also, right now, most DTV is UHF. After february, they should drop down to VHF again.

I'm 12 miles from the towers, with 2 sets of rabbit ears (VHF) and a UHF loop, and get all the DTV from around here. 

Back home (80 miles from the towers), we have a 50 foot antenna mast, we picked up mos of the more powerful DTV..basically fox, nbc, and abc.


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## cowboyup4christ (Oct 5, 2008)

magnethead said:


> Also, right now, most DTV is UHF. After february, they should drop down to VHF again.
> 
> I'm 12 miles from the towers, with 2 sets of rabbit ears (VHF) and a UHF loop, and get all the DTV from around here.
> 
> Back home (80 miles from the towers), we have a 50 foot antenna mast, we picked up mos of the more powerful DTV..basically fox, nbc, and abc.


depends on your location most low VHF in the US will be used for cell phone and emergency communications so only some High VHf and UHf will be used for digital tv. only two channels in my area will go back to VHF that would be 8 and 11. I think the problem with the signal is over load this can cause signals to breakup and can even cause you to lose 
channels with in 30 miles of transmitters do not use pre amps and for sure do not use distribution amps they have too much noise and are only use for long cable runs of over 150 feet. the pre amp will work if you are running multiple tvs but make sure it is a low noise pre amp 2.0 db Channel master and Wine Guard are the best. too much is just as bad as too little when it comes to Digital TV.:wink:


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## deanjj (Jan 8, 2009)

Try taking the amp out of the circuit and see what happens.


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## Done_Fishin (Oct 10, 2006)

best place for the amp is normally next to the aerial or as close to it as possible ..

why the biggest one you could get ? Are you a long way from the transmitter .. remember if you are not getting a strong signal then the amplifier will also amplify any noise and if you are picking up noise in your downlead that will be amplified too when the amplifier is at the wrong end of the run.

make sure that you are using good cable with the right impedance - matched to aerial, amplifier & TV to avoid reflections and ghosting


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## magnethead (Mar 18, 2006)

Done_Fishin said:


> best place for the amp is normally next to the aerial or as close to it as possible ..
> 
> why the biggest one you could get ? Are you a long way from the transmitter .. remember if you are not getting a strong signal then the amplifier will also amplify any noise and if you are picking up noise in your downlead that will be amplified too when the amplifier is at the wrong end of the run.
> 
> make sure that you are using good cable with the right impedance - matched to aerial, amplifier & TV to avoid reflections and ghosting


agreed. Also, im hearing mixed reviews of having amplification of a OTA DTV line. Some times it works, sometimes it doesnt. Also, if you have a line splitter/combiner, the "DC pass" side does NOT relay OTA DTV I have found.


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## Done_Fishin (Oct 10, 2006)

at this point, you know a lot more than I do .. all my work was from the days of analog .. and I haven't kept in touch with Digital Reception Techniques .. just going by my old experiences leading up to 2001.


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## magnethead (Mar 18, 2006)

Done_Fishin said:


> at this point, you know a lot more than I do .. all my work was from the days of analog .. and I haven't kept in touch with Digital Reception Techniques .. just going by my old experiences leading up to 2001.


my entire dorm room runs on the OTA DTV thru my TV tuner..only time i use the cable feed is for the ESPN and what not channels. 

and thus, i've found many combinations that do and dont work.

I go back next week. But what i found worked was cable to the TV input (I have HVR-1600 with FM), a set top antena going into a combiner with a pair of old rabbit ears using a non dividing combiner, going to the antenna port, then FM antenna with amplifier turned off to FM port


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