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Old 28-Oct-2015, 9:10 PM   #1
billfr
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Need help in Columbus OH receiving ABC and PBS stations

My location is: http://www.tvfool.com/?option=com_wr...8e0341acade75b

The stations I want to receive are: ABC, NBC, CBS, Fox and PBS.
I had professional installers install a Channel Master 4221 in my attic. I have good reception for NBC, CBS and Fox. With ABC and PBS I get interment pixilation / breaking up of the picture. I get this enough that it makes viewing unacceptable.

The installers mounted the antenna is the easiest place in the attic to do so (the part of the attic that has plywood over the rafters and no insulation). The rest of the attic has 14 inches of insulation that cover the rafters and would be difficult to navigate. RG6 cable was used. There is probably 25 ft RG6 cable of connecting the antenna to a TIVO.

The installers aimed the antenna 107 Magnetic North. When I repositioning the antenna to 120 Magnetic North I get ABC with no reception problems, but PBS has a lot of interment pixilation / breaking up of the picture. When I repositioning the antenna to 95 Magnetic North I get PBS with no reception problems, but ABC has a lot of interment pixilation / breaking up of the picture.

Here are my questions:

1. Should the installers have tried more places in the attic to mount the antenna?

2. Is the Channel Master 4221 the correct antenna for my location considering that PBS is 59 Magnetic North and ABC is 156 Magnetic North?

3. Would an omnidirectional antenna like the Winegard MS-2002 mounted in the attic be a better choice?

4. Do I need two antennas?

5. It appears that Fox and ABC come from the same tower. Why can I get a rock solid signal for Fox, but have intermittent problems with ABC?

Can anyone provide me with any guidance? Thanks in advance.
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Old 28-Oct-2015, 9:44 PM   #2
Jake V
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1. Yes. The installer should have experimented and chosen a location in which you received all the channels you wanted. From your description it sounds like they put it in the easiest place to access. Attics are difficult places for attics as there can be lots of interference.

From the standpoint of the antenna, what does it "see" in the directions of 59 degrees and 156 degrees besides plywood? Does it look through shingles? Metal siding or trim? Metal pipes or electrical wiring? After it "looks through" the roof or siding what does it see in those directions? Trees? Houses? Buildings? Mountains?

2. The best antenna is the one that works. I would have started with either a ANT-751 or a Antennas Direct C2 aimed at 107 degrees. What the installers tried to do is to split the difference between the channels at 59 and 156 degrees. You've taken it down to 95 degrees. Did you do it a few degrees at at time? Maybe there is a sweet spot. If it's on a pole, I'd also try moving up and down a few inches.

3. Maybe. Maybe not. Omni-directional antennas are usually not very good.

4. No. An extreme measure would be the Antennas Direct Db-8e. It has two panels, each of which can be aimed independently, and when they are set as an outside corner (90 degrees) they seem to perform OK for signals that are about 90 degrees apart (and yours are 97 degrees apart).

5. Lots of reasons. Sometimes a transmitter can be a few feet higher or lower on a tower. Sometimes trees block some signals but not others.

Others will post. Experiment with the aim of the antenna. You might also consider buying another antenna like the ANT-751 from Best Buy or Walmart and experimenting (both have easy return policies).

Last edited by Jake V; 28-Oct-2015 at 9:46 PM.
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Old 29-Oct-2015, 12:10 AM   #3
billfr
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Hello Jake V,

Thanks for the quick reply.

The roof is asphalt.

The house is all brick, although the soffit has been covered by aluminum.

It is relatively flat here and there are no buildings of any size. All residential housing.

There are some mature trees in the general direction of the towers. The trees are not on my property, but on my neighbors.

I will continue to experiment with re-aiming the antenna a few degrees at a time. I have been using the compass on a smartphone, would you suggest a different compass.

I will post again after experimenting with different positions for the antenna and/or installing one of the antenna's you have suggested.

Thanks again.
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Old 29-Oct-2015, 12:37 AM   #4
Jake V
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OK. I'll take it that the antenna looks through the asphalt roof and not through anything metal.

Smart phone compasses are not usually reliable. It's best to get a $5 compass at Walmart or a sporting goods store. However, an easy experiment is to aim it where you get PBS strongly but loose one or more of the others and then move the antenna a little at a time towards the the other stations. You might find a sweet spot. If it's easy to do, move the antenna up the pole a few inches. If it's already as high as it can go in the attic then try moving it down a few inches. Basically it's trial and error.
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Old 31-Oct-2015, 1:03 AM   #5
skatingrocker17
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In the summer of 2014 I lived on the far West side of Columbus right off Hillard Rome road because I had an internship downtown. My 2nd floor apartment faced the west (away from all the towers which are mostly all downtown). I had a ClearStream 2V was faced away from the Columbus towers towards Dayton because I wanted to receive ALL the stations. I had had no issue getting all of the Columbus stations along with many of the Dayton ones which where exactly 60 miles away from my location.

It's all about placement. I believe your antenna is UHF only, but luckily for you all of the main stations are UHF.

I now live in the metro Detroit area where my signals are almost always 100% but I get some intermediate spikes to 0% because of high airplane traffic, which on some days (depending on wind conditions) they will fly right over my apartment and knock the signal out for a few seconds. Are you near the airport?
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Old 2-Nov-2015, 12:50 AM   #6
billfr
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skatingrocker17,

Thanks for the reply and advice. I took Jake V's advice and purchased an RCA751. I am getting better reception with it than I was with the ChannelMaster. I plan on adjusting the aim in the next couple of days to see if I can consistently get the five networks in Columbus. If I can't then I will try the ClearStream 2v.

I will post again when I get my results.
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Old 8-Nov-2015, 8:58 PM   #7
billfr
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UPDATE: Need help in Columbus OH receiving ABC and PBS stations

UPDATE:

I have been using the RCA 751 for 9 days now. After re-adjusting the aim a few times I am getting the following results.

NBC, CBS, FOX and PBS have excellent reception all the time.

ABC reception is confusing. On most days I get interment pixilation / breaking up of the picture during the DAY time hours. BUT in the EVENING I get very good reception. Since my main concern is the evening hours I can live with that.

But I am curious if anyone knows why the reception is different during the day versus the evening.

I am glad I found this forum and appreciate the help I have received.
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Old 8-Nov-2015, 11:07 PM   #8
rabbit73
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Quote:
But I am curious if anyone knows why the reception is different during the day versus the evening.
Although Fox and ABC have their antennas on the same tower at about the same height, their transmitting frequencies are different which can create differences in propagation. Other possible causes:

1. Temperature inversions

2. Fox antenna polarization is horizontal 1000 kW ERP; ABC is 1000 kW horizontal and 600 kW vertical
http://www.rabbitears.info/tvq.php?r...ms&facid=74137
http://www.rabbitears.info/tvq.php?r...ms&facid=56549

3. Trying to "split the difference" with antenna aim makes the received signal more susceptible to multipath reflections. The most favorable ratio of direct signal to reflected signals is when the antenna is aimed directly at the transmitter.

Switching to an antenna with greater horizontal beamwidth doesn't always work. Sometimes it is necessary to have a separate antenna for each direction for best results.

TiVo tuners are known to be more susceptible to multipath interference than TV set tuners as forum member mulliganman found out with his Roamio. If your TiVo has a Diagnostics Screen, monitor not only signal strength, but also SNR and uncorrected errors when adjusting antenna aim.

thread:
question regarding overamplification
http://forum.tvfool.com/showthread.php?t=15025

posts:
before improvements
http://forum.tvfool.com/showpost.php...8&postcount=15
after improvements
http://forum.tvfool.com/showpost.php...6&postcount=21

His solution was to move his C2V to a better location where there were fewer multipath reflections and more direct signal.

4. ABC is on real channel 48, making it more likely to be affected by 4G LTE interference from cellular transmitters moving into frequencies previously used by TV transmitters in the channels above 51.

5. Your signals are extremely strong. If the attic loss is minimal, there is the possibility of partial overload which can create spurious signals from IMD (Intermodulation Distortion) in the tuner that can affect signals that are weaker than your strongest signals.

WCMH has a Noise Margin (outside and in the clear) of 73.6 dB before adding antenna gain; which is overload territory.



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

6. You have some strong local FM signals that might interfere with TV reception.

http://www.fmfool.com/modeling/tmp/1...1/Radar-FM.png
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Last edited by rabbit73; 9-Nov-2015 at 12:26 AM.
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Old 8-Nov-2015, 11:27 PM   #9
billfr
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Hello Rabbit73,

I considered 2 antenna's briefly, but most of my research seemed to indicate that a two antenna solution could be fairly difficult to pull off.

When Spring 2016 arrives and the mature trees in my neighborhood have all their leaves again, I am concerned that they could cause considerable multipath interference.

One person I spoke with recommended the DB8e.

Is there a two antenna solution you would recommend?

Thanks
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Old 9-Nov-2015, 12:39 AM   #10
rabbit73
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Quote:
I considered 2 antenna's briefly, but most of my research seemed to indicate that a two antenna solution could be fairly difficult to pull off.
Yes, difficult but not impossible. Sometimes you don't have many options. Two UHF antennas aimed in different directions are not easily combined, especially if you have a DVR.
Quote:
One person I spoke with recommended the DB8e.
An antenna that has two panels that can be aimed in different directions sometimes solves the problem, but it doesn't work as often as the marketing guys say it will. It's trial and error. When the same signals from each panel arrive at the combining point they will interfere with each other if they are not in phase.
Quote:
When Spring 2016 arrives and the mature trees in my neighborhood have all their leaves again, I am concerned that they could cause considerable multipath interference.
Trees can really mess with TV signals. See attachment.
Quote:
Is there a two antenna solution you would recommend?
Two UHF antennas, like two 4221s or a 4221 and a 751. First you must be certain that each antenna gets what you want from its direction before you try to combine them.

You could have an A/B switch to select which antenna you want.

You could have one antenna go to the TiVo and one antenna go to the antenna input of the TV.

You could have a custom AC7 filter for real channel 38 from Tin Lee to combine PBS with the other channels, like mulliganman did.
http://www.tinlee.com/PDF/AC7-custom...kup%20Info.pdf
Attached Images
File Type: jpg Trees and UHF2.JPG (101.4 KB, 309 views)
__________________
If you can not measure it, you can not improve it.
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Last edited by rabbit73; 9-Nov-2015 at 1:11 AM.
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Old 13-Nov-2015, 8:12 PM   #11
WIRELESS ENGINEER
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You may be better off with an antenna like the Xtreme Signal HDB8X from Solid Signal

It's able to be directed in TWO different directions and at $49.95 it's hard to go wrong
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Old 21-Nov-2015, 3:59 PM   #12
billfr
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CM4221 & RCA 751 can't pull in all 5 stations

After many many trips to the attic to re-position the RCA 751 antenna I have determined both the CM4221 and the RCA 751 cannot get a strong enough signal for both PBS (59 magnetic north) and ABC/FOX (156 magnetic north). The company I hired to install the CM4221 in the attic is coming back and installing the Solid Signal Xtreme Signal HDB8X.

I will post again after I see how the HDB8X performs.

I really appreciate everyone's suggestions and advice.
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Old 16-Feb-2016, 12:32 AM   #13
billfr
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Reception problem resolved

Hello all,

I have been using the Solid Signal Xtreme Signal HDB8X VHF/UHF Outdoor TV Antenna (HDB8X) for about 3 months now. The reception is excellent.

If anyone has a situation like mine, where stations you need are 100+ degrees apart, then I can highly recommend this antenna.

In my location PBS is at 52 degrees and CW is 180 degrees. I get excellent reception of both these stations with the HDB8X.

I should point out that the station (CW) farthest away, is 32 miles from my location.

I want to thank everyone who helped me with this problem. This is a great forum.
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