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Quote:
Originally Posted by MajesticPete /forum/post/17533959


Hi, I'm using a TERRESTRIAL DIGITAL Lacrosse A HDTV Antenna With Amplifier installed on the roof of a 2-floor house.


The setup is coax from antenna (roof) goes to the basement into the amplifier (came with antenna, plugs into the outlet) > into an x8 splitter (LaVa, from ebay, cheap, and covers cable/sat/OTR freq., unamplified) > to TV.


To summarize: antenna > ~60ft rg6 > amp > 1ft rg6 > x8 splitter > ~40ft rg6 > TV.


PROBLEM:

if i use the splitter, i get like 3 channels (of about 15), and all 3 are freezing/pixelerated.

if i remove the splitter (connect from amp rg6 to rg6 that leads up to TV, by using just a regular connector) i get possible channels w/ perferct picture.


Is there any other splitter i should try, or are they all the same?


TIA.

-mp

Try a Channel Master CM3418 distribution amp instead of the splitter.
 

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Quote:
Originally Posted by Colm /forum/post/17529956


Not true. You will get 100% of the signal from each antenna, less the loss inherent in the combiner, about .5dB. or about 12%. If the signals are in phase, they will sum. That is why you can get about 2.5 dB if you properly combine the signals of two identical antennas. If they are totally out of phase they will cancel. And if somewhere in between, the result will be in between.


If you get a given channel only from one of the antennas, you will have about 12% less signal strength after going through the combiner than if the combiner was not there, or about 84%.

Colm is 100% correct. I think why splicer010 isn't seeing this is because according to his post "In my situation, I have 2 UHF antennas pointed in different directions" doing this will result in losses. As Clom said above the signals must be in phase(exact same antennas and pointed in the exact same direction). The only way you can have different antennas pointed in different directions and see appreciable gains is if each antenna is a different band(UHF/VHF, VHF high/VHF low, etc.) or separate channel antennas in conjunction with the correct combiners(not just a regular splitter). In this case you will be seeing only particular frequencies on each antenna, they won't be combining same frequency's for a net gain.

Again if you you have a strong enough signal you may have luck with 2 different antennas pointed in 2 different directions with just a simple backwards splitter(in which case that might be good enough for you) but you'd have even better luck doing it correctly.
 

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I'd like to build an antenna for my attic to receive OTA signals. According to AntennaWeb I need a "Yellow" type antenna. Is the basic 4-bay DIY antenna the best for my purposes? The 1st post hasn't been updated in years so I figured I'd post.
 

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Hi jjeff. I have 2 UHF antennas that are identical make/model but pointed in different directions. Just so you are clear on what I am using.


Quote:
Originally Posted by dr1394 /forum/post/0

Quote:
Quote:

Originally Posted by Splicer010

LOL! Sorry partner. A passive combiner does not raise/add signal level. Quite the opposite really.

LOL right back at you. You're the one that's wrong.


Ron

Too funny. Please explain to me and everyone else Ron, just how a passive combiner itself can raise/add signal level then.
 

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Quote:
Originally Posted by superorb /forum/post/17538342


I'd like to build an antenna for my attic to receive OTA signals. According to AntennaWeb I need a "Yellow" type antenna. Is the basic 4-bay DIY antenna the best for my purposes? The 1st post hasn't been updated in years so I figured I'd post.

What channels do you wish to receive VHF, UHF or both?
 

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Quote:
Originally Posted by arxaw /forum/post/17538967


What channels do you wish to receive VHF, UHF or both?

I'm not sure really. I'd like to receive HD OTA channels, but I don't know if they're broadcast in UHF or VHF in my area.
 

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Quote:
Originally Posted by keenan /forum/post/17539002


Try the below site, just put your zipcode in the form and it will generate a list of the channels available in your area.

http://www.tvfool.com/index.php?opti...pper&Itemid=29

Ok, got it. I'm only interested in the major networks like ABC, NBC, FOX, etc. It doesn't look like much else that I'd normally watch anyways. I'm only 13 miles form the transmitter so I'm pretty close. How can I tell if these stations are UHF or VHF now?

 

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See the two charts at the bottom? There's one for VHF and another for UHF.


It looks to me like all your major nets, CBS, NBC, PBS, FOX, CW are all UHF and the ABC channel is VHF.
 

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Quote:
Originally Posted by keenan /forum/post/17539069


See the two charts at the bottom? There's one for VHF and another for UHF.


It looks to me like all your major nets, CBS, NBC, PBS, FOX, CW are all UHF and the ABC channel is VHF.

So it looks like all UHF with the exception of 1 station on the High VHF scale.
 

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Quote:
Originally Posted by keenan /forum/post/17539131


That's what I see, yes.

So back to my original question, what would be the most effective antenna for me to build provided it will live in the attic out of sight? Thanks for the help thus far.
 

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Quote:
Originally Posted by superorb /forum/post/17539184


So back to my original question, what would be the most effective antenna for me to build provided it will live in the attic out of sight? Thanks for the help thus far.

At 13 miles with line of sight you're not going need much. I use a 91XG myself but that's because I'm a good 60 miles from the transmitter. Hopefully some folks here more familiar with close range antennas will give you some recommendations.
 

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Quote:
Originally Posted by superorb /forum/post/17539184


So back to my original question, what would be the most effective antenna for me to build provided it will live in the attic out of sight? Thanks for the help thus far.

I don't know that a single aim will be possible for all of your channels, such as PBS. You might want to try a single classic bowtie near a window first. I know it is a UHF antenna, but the flat wire also acts as an antenna. I've reliably received rf 9 (Nm db 54) with a bowtie for over a month now. You've got stronger signal there than I have here. It might work. Good Luck.
 

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Quote:
Originally Posted by Splicer010 /forum/post/17538907


Too funny. Please explain to me and everyone else Ron, just how a passive combiner itself can raise/add signal level then.

?


The -3.5db loss on each leg is if it is used to split the signal or assuming lack of phasing if used as a combiner. 3db is 50 percent loss due to the split (or incorrect phase) and .5 db is through-loss.


However, if you phase properly with two identical antennas pointed in the same direction and equal coax lengths to the combiner you'll see increased performance over a single antenna even using a common splitter. The problem is that common splitters just don't phase very well no matter what. That's the reason stripline combiners work better.


In your situation with the antennas pointed in different directions, the -3.5 db loss should be roughly accurate. Additionally, though, you generate multipath which is the reason it would be technically better to use an A/B switch and two downleads.
 

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I have found the Apex DT502 to be very useful when trying to solve OTA antenna problems. It gives not only signal strength but also signal quality. It's a measurement bargain even without the coupon. But, the supply has dried up, so I wanted to try the Centronics ZAT502 HD because it has the the same tuner and dual signal bars. The Centronics is in short supply and I noticed that some Sony TVs have a diagnostics screen mentioned in the pdf manual but no screen shots of it.

I went to a local store to look at the diagnostics screen in the menu of a KDL-26L5000 and then ordered a KDL-22L5000. (The KDL-xxM3000 manual also mentions a diagnostics screen.) The diagnostics screen looks like this:




Now that I have all three units I am able to make a comparison using them, a SLM (signal level meter), and a 4-way splitter. My previous tests were done in my car to get away from the street traffic in front of my antenna at home that causes the readings to vary (but the signals stay locked when they are strong) and I was able to drive to strong and weak signal areas. I couldn't work that out because having the 22-inch TV in the car was a big logistical problem. I stayed at home, ran the tests at night with light traffic, and used preamps to vary the signal levels. I also rigged up a mic, amp, and speaker to listen for the traffic to ignore readings when cars were passing by.


The first test used two preamps; a CM7777 near the antenna and a RS 15-1115 inline preamp (one of my better RS purchases) before the attenuator to find out where the signal meters maxed out:

antenna-> 7777-> 50 ft coax-> CM power inserter-> RS amp-> attenuator-> 4-way splitter:

Code:
Code:
Attn    Apex   Centronics       Sony          SLM     Equiv
 dB    Q    S    Q    S      S   Er   SNR     dBmV     dBm
  0   100  87   100  89     79   0    25     +18.5   -30.3
  3   100  86   100  89     79   0    25     +15.0   -33.8
  6   100  86   100  89     79   0    25     +11.9   -36.9
  9   100  86   100  88     79   0    25      +8.8   -40.0
 12   100  85   100  88     79   0    25      +5.9   -42.9
 15   100  85   100  88     79   0    25      +3.1   -45.7
 18   100  83   100  87     79   0    25       0.0   -48.8
 21   100  79   100  85     79   0    25      -3.5   -52.3
"Q" is quality, "S" is strength.

Sony IF-AGC figures not listed because in all cases they were the same as strength.


The RS preamp was removed, leaving only the 7777 (my normal setup):
Code:
Code:
Attn    Apex   Centronics       Sony          SLM     Equiv
 dB    Q    S    Q    S      S   Er   SNR     dBmV     dBm
  0   100  84   100  88     79   0    25      +3.0   -45.8
  3   100  81   100  87     79   0    25      -0.8   -49.6
  6   100  78   100  84     79   0    25      -3.9   -52.7
  9   100  73   100  80     78   0    25      -7.0   -55.8
 12   100  69   100  76     76   0    25     -10.0   -58.8
 15   100  66   100  71     74   0    25     -12.9   -61.7
 18   100  62   100  67     71   0    25     -15.7   -64.5
 21   100  58   100  63     69   0    25     -18.6   -67.4
 24   100  54   100  59     66   0    25     -21.6   -70.4
 27   100  49   100  54     62   0    24     -25.4   -74.2
 30   100  45   100  50     59   0    23     -28.2   -77.0
 33   100  38   100  45     55   0    21     -32.0   -80.8
The 7777 was removed (to simulate weak signals) leaving only the coax between the antenna and the attenuator:
Code:
Code:
Attn    Apex   Centronics       Sony          SLM     Equiv
 dB    Q    S    Q    S      S   Er   SNR     dBmV     dBm
  0   100  55   100  58     66   0    24     -22.0   -70.8
  3   100  49   100  53     62   0    24     -25.9   -74.7
  6   100  45   100  49     58   0    22     -29.0   -77.8
The RS preamp was inserted between the splitter and the SLM because the meter was near the bottom of scale, and I repeated the test just above. The preamp noise figure does not affect the tuners because it isn't in line with them:
Code:
Code:
Attn    Apex   Centronics       Sony         SLM+amp dBmV corr  Equiv
 dB    Q    S    Q    S      S   Er   SNR     dBmV    for amp    dBm
  0   100  54   100  58     66   0    25      -6.1    -22.1    -70.9
  3   100  49   100  53     62   0    24      -9.3    -25.3    -74.1
  6   100  44   100  49     58   0    23     -12.1    -28.1    -76.9
  9   100  38   100  44     55   0    21     -14.9    -30.9    -79.7
 12    77  27    65  38     55   0    18     -18.1    -34.1    -82.9
 15    26V  0    20V 27     55   0    16     -21.2    -37.2    -86.0
 18   dropout   dropout     55 3099V  13F    -24.3    -40.3    -89.1
A "V" after a figure means that it varies; the Sony errors are updated about once every second. An "F" after the SNR means that the display is frozen at that value. Adding even more attenuation makes the Sony screen go black and say "no signal." At least 15.5 to 16 dB SNR is needed to maintain lock.


When aiming or comparing antennas using the signal strength meter you must keep it below the max value (where your meter doesn't go any higher) by using an attenuator. In my case, that would mean keeping it well below 86 for the Apex, 89 for the Centronics, and 79 for the Sony.


Attachment No. 1 shows a Sony "frozen screen" at 13 dB SNR.

Attachment No. 2 is the RS preamp specs.

Attachment No. 3 is the RS preamp diagram. RS used to print diagrams in the manual, but they don't anymore . I think that's a mistake, because showing the diagram encourages experimentation, which means more sales. Looking at the diagram, you can see how the RF signal and the DC power are combined on the coax using capacitors and chokes (inductors). Capacitors pass RF but block DC; chokes pass DC but block RF.



 

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Yesterday, I installed two Winegard antennas - YA-1713 high VHF, and a 9095P UHF. Each has a plastic box with a PC board balun, to provide 75 ohm connections. However, the UHF one also has a connector for a VHF antenna, so I guess that is a combiner also. I am using a CM7777 preamp with dual inputs, so I don't use the combiner mounted on the UHF antenna, so I put a 75 ohm cap on that input. How does this configuration relate to the discussions above?


This appears to work well, pulling in WNJN RF 51 in New Jersey, 55 miles away fairly well. I still don't get WCBS RF 22 or WWOR RF 38 (I get all the other NYC stations, as well as some CT ones). Tomorrow, I am getting a 24 ft mast to raise this assembly (currently the VHF one is about 1 ft above my porch roof, and the UHF one is below it - my current 10 foot mast is mounted on my deck). Any suggestions? I'll post a photo of this assembly when I can get one (it's nightime now).
 

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Quote:
Originally Posted by deltaguy /forum/post/17539443


I don't know that a single aim will be possible for all of your channels, such as PBS. You might want to try a single classic bowtie near a window first. I know it is a UHF antenna, but the flat wire also acts as an antenna. I've reliably received rf 9 (Nm db 54) with a bowtie for over a month now. You've got stronger signal there than I have here. It might work. Good Luck.

I'm only interested in the major networks like ABC, NBC, FOX, CBS.
 
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