Need help with DTV in Chicago suburbs

Hi, I could use some advice for an antenna set up I can't quite get to work perfectly.
I have an Antennacraft HBU33 that I bought from Radio Shack today.
My AntennaWeb results are (from Wheaton, IL):
Antenna Type Call Sign Channel Network City, State Compass Heading Miles From RF Channel
red uhf WFLD-DT 32.1 FOX CHICAGO, IL 89° 24.2 31
red uhf WCIU-DT 26.1 IND CHICAGO, IL 89° 24.2 27
red vhf WBBM-DT 2.1 CBS CHICAGO, IL 89° 24.2 12
red uhf WGN-DT 9.1 CW CHICAGO, IL 89° 24.2 19
blue uhf WGBO-DT 66.1 UNI JOLIET, IL 86° 25 38
blue uhf WJYS-DT 62.1 REL HAMMOND, IN 89° 24.2 36
blue uhf WCPX-DT 38.1 ION CHICAGO, IL 86° 24.3 43
blue uhf W57DN 57 TBN LASALLE, IL 327° 12 57
blue vhf WLS-DT 7.1 ABC CHICAGO, IL 89° 24.2 7
blue uhf WSNS-DT 44.1 TEL CHICAGO, IL 89° 24.2 45
blue uhf WXFT-DT 60.1 TFA AURORA, IL 89° 24.2 50
blue uhf WTTW-DT 11.1 PBS CHICAGO, IL 89° 24.2 47
blue uhf WMAQ-DT 5.1 NBC CHICAGO, IL 89° 24.2 29
blue uhf WPWR-DT 50.1 MNT GARY, IN 89° 24.2 51
violet uhf W40BY 68 TBN LASALLE, IL 89° 24.2 68
violet uhf WOCH-CA 41 IND CHICAGO, IL 86° 25 41
violet uhf WYCC-DT 20.1 PBS CHICAGO, IL 86° 25 21

For various reasons, I need to install this antenna in my attic--outdoors is not an option at this point. I can get most of the channels I need reasonably well, but reception on FOX (WFLD) is spotty, and I can't pull in WMAQ for NBC. I tried attaching a small signal amp in the attic next to the antenna, but that seemed to do more harm than good.

One of my biggest problems is that it's a real pain to go up in the attic, tweak the antenna, then come back down and do a full signal scan on my TV to see if I got NBC. Surely there's a better way to do this (without spending a ton of money on a signal meter).

Any advice would be much appreciated.

Since I can't make a damn bit of sense from the antenna web report, I will post a generic address TVfool report for Weaton.

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d8ecdd968771043

Which shows that all your Chicago stations are basically due east of you and are a mixed bag of VHF and UHF.

And to go into trouble shooting mode, I do not know much about your specific antenna, I might suggest basic aim and almost TVsignal opaque building materials in your attic as big problems.

I would also suggest that you are almost a prime candidate for a good preamp, because you should be doing better.

Just my initial take, lets see what others suggest.

Well, it basically came down to a full evening of trial and error, but I finally got all the essential stations with good stable signal. I'm just glad I won't have to go through that again unless they move the Sears Tower.

When you buy a small, cheap antenna and you put it in the attic - with no antenna rotor and expect it to work, then you usually get what you pay for.

Since I have to put it in the attic, and I don't want to spend any money, then I must do a little more leg work to get it to work.

I wouldn't expect much more than spotty performance at best.

Once you get a couple of inches of snow on the roof of the house, your signals might all disappear.

JB, why would he need a rotor? All of his/her channels are in a very narrow band.

Sorry, duplicate post

I would hardly call the HBU33 a small and cheap antenna although the on aim gains of about 7.6 db is not that impressive.

But still, if the doom and gloom or Jbantennaman does come to pass in snow, a fairly inexpensive preamp could probably make up the difference.

But if our OP now has the antenna facing through a East facing vertical gable end, or the roof pitch is steep, accumulating snow is not a worry.

In short, congratulation dgodoy, and you have a working setup going as your efforts have been rewarded with results. And results are all that matter.

JB, why would he need a rotor? All of his/her channels are in a very narrow band.


Yea, pretty much all the Chicago channels are from atop the Sears Tower (still refuse to call it the Willis) and a couple (86 degrees) are atop "The Cock" about 3 miles or so away.

NonMcTubber, what would you recommend for a preamp? I don't mind spending money, as long as it's quality.

dgodoy,

The appropriate pre-amp depends on your tv distribution system. How many tvs and how many feet of cable do you have in your distribution system. A Winegard HDP-269 is good if you only have 1 or 2 tvs and less than 100 ft of cable run.

HTH,

Rick

The Channel Master 7777 Titan is a good pre-amp and can be had for around $50-$60..

http://www.warrenelectronics.com/antennas/7777.htm

I have one tv, and no more than 50 feet of cable. I'll look at the Winegard HDP-269.

Thanks,
Dan

Too much signal can cause intermittent/spotty reception problems as well as create false signal strength readings. WFLD and WPWR are both pushing 1 MW, both with antennas on the west side of Willlis Tower. You might try adding a splitter or 3 dB pad to see if your performance improves or worsens.

To dgodoy,

If you are getting all channels now, why waste money for a preamp? Its only if you have future problems in snow where you
might consider curing your yet to be realized problems with a preamp.

And if you have future problems, the most cost effective solution is and remains getting the antenna from the attic to the clear air above the roof. And in your case, you don't need to be much above your roof.

But who knows, you may also see some channels drop out with rain
also, and it takes a while to learn your long run average.

While I agree with NMT that a roof mount usually gives superior performance over an attic mount, I also understand the reasoning behind wanting an attic install. A pre-amp will likely give dgodoy a signal boost of 6dB at his television (3 dB lost in cable run and 3 dB difference between pre-amp NF and tv tuner NF). This is a fourfold increase in signal and adds margin to his current set up.

Despite my initial success getting good reception on all channels, I lost channels the next day. Maybe air quality, or some other variable. So it seems worth the money to get the pre-amp. Hopefully this makes my reception more stable and consistent on all channels. I might also try swapping out all my coax with new wire... I have my doubts about the quality of the existing coax infrastructure in this house. There are at least three connection points (a splitter and two joiners), all of them unnecessary if I just get a single 50 foot cable.

Is it likely that I'm losing much signal with those connections? Should I try replacing the coax before buying a pre-amp?

Good questions Dan! The splitter decreases signal by ~3.7 dB and each coupler has an insertion loss < 0.5 dB. You can more than double the signal by removing the splitter and couplers. Replacing the cable may give you another 1 dB savings if you're replacing rg59 with rg6 cable. I would do both to reduce the losses. Optimally, you want at least a 10 dB margin for each channel. IMO, the pre-amp is appropriate with an attic install and I would order the HDP269 pre-amp. You can still use this pre-amp outdoors if you decide to go with a roof mount.

HTH,

Rick

Dan,

Can you go to www.tvfool.com and enter your actual address plus antenna mounting height? Post the link to the results in your next reply to this thread. It is important to verify that NMT's generic tvfool result for Wheaton, IL actually matches what is going on at your location. According to tvfool, the chicago towers are 1 edge from wheaton (means a big ridge somewhere between wheaton and the sears tower. If you're closer to the ridge than the average wheatonite, then your situation will be poorer and vice versa.

Can you describe what happens when your two stations "fail"? Are they completely gone or are they breaking up, pixelating, or video dropouts?

Thanks,

Rick

Here's my result:
http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d8ecd37f14a73ab
I didn't see information about edges or ridges... I know I am in a low-lying area (i.e. near a flood plain).

Oh, now I see the "edge" information in the chart. 2 Edge on all the channels I care about. Seems like that's a bad thing. Is it?

I must not be interpreting this wealth of data correctly. Let's take the station that gives me the most trouble, WMAQ, which has an NM of ~30. I add 7.6 dB for my antenna, subtract 4.7 dB for my splitter and two couplers, subtract 1 dB for my 50 feet of coax, and I'm still left with a noise margin well over 30. Do my roofing material and tree in front yard actually cost me 30+ dB?

thanks for posting your tvfool!

2-edge means that the signal is defracting/bending over two edges to get to your place. It isn't necessarily a "bad thing", rather it means that you may have to work a bit harder to find the "signal hot spots" in your area. Mounting the antenna out on the roof may enable you to find the hot spots easier than in the attic.

I must not be interpreting this wealth of data correctly. Let's take the station that gives me the most trouble, WMAQ, which has an NM of ~30. I add 7.6 dB for my antenna, subtract 4.7 dB for my splitter and two couplers, subtract 1 dB for my 50 feet of coax, and I'm still left with a noise margin well over 30. Do my roofing material and tree in front yard actually cost me 30+ dB?

First, tvfool NM are estimates rather than actual measurements and do not account for all the possible environmental losses between the broadcast towers and your place.

Second, trees can sap alot of signal. One study that I found suggested ~7 to 15 dB loss depending on tree type, diameter, amount of foilage, moisture on leaves, etc.

Third, the amount of signal loss from an attic install varies tremendously. Most people state that you lose 1/2 your signal from an attic install (equates to 3 dB loss). However, I am aware of a study where an engineer measured 13 dB loss with an attic install (asphalt shingles and plywood deck). In my testing, I lose about 3 to 4 dBs with an attic install.

Fourth, tv tuners vary in Noise Factor. Latest generation digital tuners do much better than older tuners and handle multipath better than older tuners.

Fifth, you must subtract 1.5 dB for the balun, 3dB for rg6 cable or 4dB for rg59 cable, and 6 to 10 dB for the tuner.

You may see a huge improvement and signal strength by moving the antenna out on the roof and away from the tree. At my place, I lose 12 dB's on Fox if the antenna is on the south edge of the roof versus the north edge of the house. Why, trees! North side has clear LOS.

HTH,

Rick

To dgodoy,

In comparing the generic to your exact address report, it looks like your distance to the Sears tower is the same, but most of your stations switch from one edge to two edge.

So IDRick nailed it when he noted, "If you're closer to the ridge than the average wheatonite, then your situation will be poorer and vice versa.

Can you describe what happens when your two stations "fail"? Are they completely gone or are they breaking up, pixelating, or video dropouts?"

And the answer to the IDRick question of what happens when you lose a station becomes somewhat important even if you do not know your long terms average yet.

The point being, there is something called the digital cliff with digital but not analog television reception. On the right end of the digital cliff you get a perfect picture and more signal yields no better results. At exactly the digital cliff, the picture pixelates
and fades in and out. And at the wrong side of the digital cliff you get nothing as your television displays no signal.

The point being, at the digital cliff, its only a narrow range of a few db's more to get you that perfect picture, so your plan to replace your spliced coax run with a single run may be all that is needed to end your reception problems. If that later proves to be not enough, then a preamp is recommended in addition.

But in trying to save you money, I would try replacing that coax run first. If that does not keep you always on the right side of the digital cliff, then you are justified in going a preamp. If that is still not enough, getting a bigger attic antenna with a higher gain would be the next step, and then you are finally left with an outdoor antenna as a next step. And then to add injury to insult a even higher outdoor antenna mast will do even better as will an antenna rotor.

But be careful in being sucked into that expensive endless escalation game, every time you make some improvements you will find more and more new channels you never got before at the digital cliff, that you can get on good weather days and will lose on bad weather days.

So kind of decide on what stations you really want, and quit throwing away more and more money when you get that set reliably.

Great long-term advice, NonMcTubber. I'll be completely satisfied once my wife can watch her shows on NBC. I'm going to business school, and don't have much time for TV myself, so that's why I'm trying to choose my investments wisely here.

When NBC isn't coming in, there's simply no picture. When it does come in, it breaks up from time to time, but is mostly crystal clear. Most of the other stations are very good, though I'd like to see a little better on FOX (I can see pixelations when I look closely).

From my understanding of your description of the digital cliff, I have a feeling I'm close to it for most of these channels. Perhaps these infrastructure improvements will be just what I need to get on the right side for NBC. If not, I have hope the preamp will do the trick. Hopefully I'll get a chance to at least remove the splitter tonight.

You guys have been very helpful. Thanks a lot.

Dan

Video dropouts are a good indicator of multipath. In my case, the digital cliff occurs at ~30% signal strength. I had a station with 70% signal strength that experienced video dropouts during certain environmental conditions. Moving the antenna out to the roof resolved the problem.

What happens in your case? Are you close to the digital cliff or are you experiencing multipath? What are your signal strengths with your problem stations?