ABC OTA HD in Chicago (7.1)

1747 Views 16 Replies 6 Participants Last post by drmorley, Jan 31, 2006

drmorley

Discussion Starter · Jan 30, 2006

I'm currently about 13 miles (60068) from downtown and have a large (old school) fishbone antenna on our chimney that's diplexed into one of the lines that's run to our HR10-250. All my OTA locals come in great (levels in the 90s) with the exception of ABC.

For whatever reason I can only get a signal about 50% of the time. The rest of the time I get nothing or it pixelates so badly that you can't watch anything.

I applied for a DNS waiver three weeks ago and haven't heard anything yet, but I'm guessing that I'll be denied. Is there anything I can do to improve my signal strength? Currently It's in the low thirties, but drops even lower on bad days.

Thank you in advance for any advice.

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ebonovic

· #2 · Jan 30, 2006

Hmmm...

I am 35 miles away, and get a nearly 100% signal strength for ABC.. (it is CBS that I can't get).

One of two things....
1) You are getting TOO good of a signal and it is overloading,
2) ABC actually frequency range is outside the limits of your antenna... I will have to look up the frequency mapps for the channels.

drmorley

Discussion Starter · #3 · Jan 30, 2006

Is there any way I can test to pinpoint what my problem is? The Antenna is old, but it's properly anchored to the chimney and doesn't move/sway even in high winds.

It's just weird that Fox, NBC, CBS, UPN and PBS all come in perfectly with signal leves in the 90's.

SpankyInChicago

· #4 · Jan 30, 2006

drmorley said:
Is there any way I can test to pinpoint what my problem is? The Antenna is old, but it's properly anchored to the chimney and doesn't move/sway even in high winds.

It's just weird that Fox, NBC, CBS, UPN and PBS all come in perfectly with signal leves in the 90's.

ABC is on frequency 52. It could be an issue with your antenna at certain frequencies. Gain on an antenna is not equal across the frequency spectrum. I would suggest taking a look at analog 50 (WPWR?) and seeing how the reception looks. This certainly isn't a scientific test, but it should at least give you an idea if your antenna picks up that frequency range okay. You could also look at 50-1 (frequency 51) which is WPWR-DT. If you see ghosting on analog 50, you have multipath issues which might take either an attenuator or an amplifier to fix. It is also possible that you have too much signal like ebonovic said which would require an attenuator to fix. Problems like this usually result in a process of trial and error to correct. There is usually no "one size fits all answer." Good luck.

drmorley

Discussion Starter · #5 · Jan 30, 2006

Thanks for the information!

50-1 comes in great with a signal strength around 60%. When I run the OTA cable directly into my television I don't see any ghosting on analog 50, but the channel doesn't come in all that great. FWIW, none of the OTA analog channels come in that well.

SpankyInChicago

· #6 · Jan 30, 2006

drmorley said:
Thanks for the information!

50-1 comes in great with a signal strength around 60%. When I run the OTA cable directly into my television I don't see any ghosting on analog 50, but the channel doesn't come in all that great. FWIW, none of the OTA analog channels come in that well.

Does your TV have an ATSC (digital) tuner? If so, can your TV pick up 7-1?

drmorley

Discussion Starter · #7 · Jan 30, 2006

SpankyInChicago said:
Does your TV have an ATSC (digital) tuner? If so, can your TV pick up 7-1?

Yes it does. I'll test it right now to see if it works.

hefe

· #8 · Jan 30, 2006

I'm 41 miles away...WLS-DT comes in great. I'm even getting CBS pretty consistently these days.

drmorley

Discussion Starter · #9 · Jan 31, 2006

SpankyInChicago said:
Does your TV have an ATSC (digital) tuner? If so, can your TV pick up 7-1?

Okay, so I ran the antenna line directly into my television and I'm getting 7-1. The problem is that today is good day and I'm getting 7-1 when the line is run through my HR10-250.

The problem is intermitent. I'll get 7-1 for a week and then I won't get it for four days and then I'll get it for three days and then it'll disappear. I'm generally pretty good at troubleshooting, but I can't for the life of me figure out what the problem is.

ebonovic

· #10 · Jan 31, 2006

I am going to lean on the side of that the 50+ range is out of the range for the antenna you have up there... on some days when the signal is clear and nothing out there is affecting it... you have no problems

I would agree that this is VERY odd though.

drmorley

Discussion Starter · #11 · Jan 31, 2006

Which antenna would you recommend should I replace my existing model? I have no problem replacing the antenna--I just don't want to do it only to find out the problem remains.

bellbm

· #12 · Jan 31, 2006

Another thing I would try is running a wire directly from the antenna to your tv. I had similar problems, and after replacing the diplexers a couple of times, I ended up just running a separate line straight from the antenna. Now I get all of the stations, in the 80s and 90s.

Diplexers seem to be very pesky things.

drmorley

Discussion Starter · #13 · Jan 31, 2006

bellbm said:
Another thing I would try is running a wire directly from the antenna to your tv. I had similar problems, and after replacing the diplexers a couple of times, I ended up just running a separate line straight from the antenna. Now I get all of the stations, in the 80s and 90s.

Diplexers seem to be very pesky things.

I wish I could, but it's just not an option. My HD set is in the basement and since it's finished I have no way of running a cable just for testing purposes.

ebonovic

· #14 · Jan 31, 2006

The antenna I am using is a Radio Shack vx-120

but it is probably TOO BIG for your distance.

Take a look at antenna.org for some recommendations on the antenna you should try to use.

Also take a look at teh sister site... www.avsfourm.com local reception form.

TyroneShoes

· #15 · Jan 31, 2006

SpankyInChicago said:
...you have multipath issues which might take either an attenuator or an amplifier to fix...

Amps can improve reception by raising the signal further above the noise floor, and are only effective if you are not already receiving enough signal without an amp to do that. Attenuators can improve reception by lowering the signal level to where it is within the operational window of the tuner (IOW, too much signal can create overload and thwart reception) and are only effective if you aren't already at a proper level. But multipath issues can rarely be fixed by adjusting the signal level alone, because if you raise (with an amp) or lower (with an attenuator) the signal, you raise or lower the interference correspondingly the same amount. It is the ratio of MP interference compared to the desired signal that must be improved, and neither of these will likely do that.

The only real way to improve the ratio is to raise the desired signal level while not raising the undesired reflected signal, or lower the reflected signal while not lowering the desired signal. A more-directional antenna like a 4228 raises the level (at the tuner) of the signal it is pointed at while lowering the signals coming from other directions, so actually does both, and that is also sort of the definition of directionality.

The only other way (other than moving the antenna) to increase the ratio is to use a tuner that rejects out-of-time signals better. IOW, use a STB or HDTV with the NeXtwave tuner, commonly found in Zenith and LG products, and also found in the NDS HD PVR which will be out some time this year.

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bellbm

· #16 · Jan 31, 2006

I wish I could, but it's just not an option. My HD set is in the basement and since it's finished I have no way of running a cable just for testing purposes.

Disconnect one from the multiswitch and hook it up directly to the antenna.

drmorley

Discussion Starter · #17 · Jan 31, 2006

Okay, I hooked the line from the antenna into the ATSC tuner in my television (Mitsubishi WD-52628) and I get channel 50 analog without any problems or ghosting.

As of this morning ABC (WLS-DT) 52 was coming in at 60% signal strenth which is the highest it's ever been.

I'm going to explore getting a new antenna to see if that doesn't solve the problem.

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