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Discussion Starter · #1 ·
I am having trouble receiving channels that are on the same heading & distance as ones where I get a strong signal strength.


I am using a TivoHD and Tivo series 3 HD unit to receive my local channels. The previous owner of my house installed a physically large directional antenna in the attic (brand or type is unknown) and it is pointed in the correct direction. There is about a 30' run to a PDI-brand 2:1 splitter and then 30'+ of additional coax to the nearest Tivo (other leg of the splitter is probably 50-60'. Below is a cut-and-paste from antennaweb. Channel 8.1 comes in @ a strength of 99, channel 42 @ ~50 and channel 2.1 comes in @ 0. Will an amp like a Channelmaster 7778 allow me to pull in the weaker channels (without breaking channel 8.1) or is it more likely that I'm having multi-path problems (since the towers are all in ~ the same place)? In general, VHF is doing much better than UHF channels.


DTV Antenna

Type Call Sign Channel Network City, State Live Date Compass Heading Miles From RF Channel

uhf KUNP-LP 47 UNI LA GRANDE, OR 82° 11.6 47

uhf KATU-DT 2.1 ABC PORTLAND, OR 83° 12.1 43

vhf KGW-DT 8.1 NBC PORTLAND, OR 81° 11.5 8

uhf KPXG-LD 42.1 ION SALEM, OR 81° 11.5 42

uhf KEVE-LD 36.1 TBN VANCOUVER, WA 82° 11.6 36

uhf KWVT-LD 17.1 A1 Salem, OR 81° 11.2 16

uhf KPXG-DT 22.1 ION SALEM, OR 81° 11.5 22

uhf KOIN-DT 6.1 CBS PORTLAND, OR 83° 12.2 40

uhf KRCW-DT 32.1 CW SALEM, OR 83° 12.2 33

vhf KPTV-DT 12.1 FOX PORTLAND, OR 82° 11.4 12

vhf KOPB-DT 10.1 PBS PORTLAND, OR 81° 11.5 10

uhf KPDX-DT 49.1 MNT VANCOUVER, WA 82° 11.4 30
 

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If you can post your tvfool results, we can get a better idea of reception in your area( your address will not be displayed in the results).

And also if you can take a pic of your antenna that would help too.

But for starters, what I usually do to troubleshoot is eliminate any splitters and the Tivos, and have the antenna hooked up to one TV. Then go from there.


It looks like from the antennaweb results you are about 12 miles from the transmitters, so an attic antenna should be ok.
 

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Your post from the Portland, OR - HDTV thread:
Quote:
Originally Posted by Greg_R /forum/post/20786615


Is anyone having problems with channel 2.*? I'm in Hillsboro and get '0' signal strength on ch2 but plenty on 8 & other channels. I just want to rule out transmitter problems before debugging my setup, thanks!

To quote wiki :
Quote:
Hillsboro is about 17 miles (27 km) west of Portland, and immediately west of Beaverton, at an elevation of 194 feet (59 m) above sea level.

A tvfool report based on your exact address would be more accurate, but here is a report based on Hillsboro:
www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d3e474285228d9c


And a report using the tvfool maps option would look like this:
www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d3e47b7c9ae91fe


The attachment shows KATU for Hillsboro.


Your signals are very stong. Unless your attic construction is making the signals a lot weaker, I think a preamp would cause overload.


Something is not right. Your UHF channels should be doing better. Which PDI 2-way splitter are you using?
www.pdi-eft.com/htmlandflash/proprietary/mega_splinter.html
www.pdi-eft.com/htmlandflash/proprietary/digi_passi.html


Does your attic antenna have a built-in cartridge preamp?
 

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Per the TVFool report rabbit73 posted, I don't think an amp will solve any problems with any of your stations in the direction your antenna is aimed. In fact, it may make reception worse, not better. All of your signal strengths are very strong, per that report. A link to the TVFool results for your address would be more helpful, though. Your address will not display on the results page.
 

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Discussion Starter · #7 ·
I have the PDI 2-WMS5 splitter:

Code:
Code:
BANDWIDTH         5-400 MHz      400-600 MHz    600-1000MHz
INSERTION LOSS    3.6dB Max       3.8dB Max        4.0dB Max
RETURN LOSS       22dB Min        20dB Min         20dB Min
ISOLATION         30dB Min        25dB Min        25dB Min
RFI                                             -120dB Min
 

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Discussion Starter · #8 ·
So could the attic-mounted directional antenna be TOO strong? Wouldn't that manifest itself as a strong signal but poor picture? I'm kind of baffled by the '0' on channel 2.1.
 

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With a location called Hillsboro, I'd bet multipath is the issue. Strong multipath on my televisions shows up as poor signal and picture. Illogical antenna aims are the cure here. Essentially, aiming the nulls of the antenna in order to block reflections. Unfortunately, a single aim doesn't catch all channels reliably. I'm aiming for a single antenna farm, but have to do so one channel at a time. This could be accomplished if you were to try an indoor antenna. Good Luck.
 

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Multipath or interference in the frequency range that ch 2-1 is using (UHF ch 43) may be your problem. If multipath, reaiming or moving the antenna to a "hot spot" often helps. You could also try an attenuator to lower those very strong signals. The attenuator will lower all signals, including the weaker multipath signals to the point that the tuner cannot see them. But it will still have enough of the main signal to get a lock.


Attics are poor locations for the antenna if multipath is a problem. This small antenna , mounted outdoors would be plenty for your strong signals, and may work better. It might be an option, if you can't get the attic install to work right.


With your strong signals, an amp may make matters worse.
 

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Discussion Starter · #11 ·
Does Coax quality (RG-59 vs RG-6 QS) play a factor with antenna reception?

Quote:
With a location called Hillsboro, I'd bet multipath is the issue.

There are actually not many hills but there is a stand of large trees, some homes, and a medium sized airport directly in between the antenna location and the towers (which are located on top of a ridge).
 

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Quote:
Originally Posted by Greg_R /forum/post/20802350


Does Coax quality (RG-59 vs RG-6 QS) play a factor with antenna reception?


RG6 performs better. Less signal loss on long runs, especially with UHF channels. VHF channels might not get affected that much, but your still better off using RG6 whenever you can.
 

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Quote:
Originally Posted by Greg_R /forum/post/20802350


Does Coax quality (RG-59 vs RG-6 QS) play a factor with antenna reception?

It can. RG-59 varies from 60% braid shielding to braid over foil. In your case poor shielding could cause the symptoms that you're seeing.


It could also be as simple as a bad connection at an F connector or a bad balun.
 

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Quote:
Originally Posted by arxaw
Attics are poor locations for the antenna if multipath is a problem.
It depends on placement. My terrible first generation ATSC receiver hardly worked with an outdoor antenna due to multipath from a 14 story apartment building. Even large vehicles on the street would cause momentary reception problems.


Putting the same antenna in my attic allowed the two walls of a dormer to block the building (multi)path while still giving it a direct line-of-sight to the towers. The house below blocked reflections from the street. The attic gave me far better reception than all of the outdoor locations I tried.
 
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