I looked up WBBM-DT on the FCC's website (the station can't do anything without the FCCs approval) and they are still broadcasting on channel 3. I haven't looked at the timeframe but it looks like they have gone from 1kW to 2.5kW to 4.4kW.


I know this is off topic, but the FCC might sell of the VHF-LO frequencies (2-6) as the stations don't like them because of noise interference problems, but VHF-HI (7-13) is extreemly desirable and the stations wouldn't give those frequencies up without a huge fight. I know of several stations (WHEC, WHAM and WWNY) that the FCC has approved to revert to their VHF-HI channels after the analog shutdown and this wouldn't happen if they were going to sell off those channels. The FCC will probably sell off UHF channels 52-69 after the analog shutdown.

Okay, everybody, we have now been discussing this for four days with no answer. Let's take a look at the proper research technique, which doesn't start with asking a question here, but with lifting a finger (and then pressing it down on a computer keyboard; not a difficult thing).

If you live in Chicago, you know, or can find out easily, that CBS is WBBM. That should have been in the first post, but it finally appeared in the sixteenth. In post 13 I mention calling the station, but that should have been done first.

After reading post 16, I made a wild-ass guess that www.wbbm.com might be the web site of the station. If you know the call letters, you don't even have to call up google to try this out, and it usually works: take the call letters and add .com to them. Is this research technique too dense for you?

On the Home Page, there is a column of links along the left edge of the screen. Under CONTACT US is a list named "Phone Numbers and Mailing Address." The fifth item is "24-Hour TV Reception Problem Hotline: 312-202-2375."

I located this at something like 1:00 a.m. local, which was 3:00 a.m. in Chicago. What the hell, I thought! I called it. I was actually disappointed after it said "24 Hour" that I got a recording. Nonetheless, the recording said to leave a detailed message and someone would get back to me within 24 hours. It was worth a try. I explained the situation, including that I was calling from Los Angeles, and figured I would hear from someone on Monday.

I went to bed.

At 5:38 my time, my phone rang. It was a really well-informed engineer from WBBM who APOLOGIZED for not calling back sooner, but they had had a transmitter go down in addition to having the HD transmitter off the air for service. (After midnight on Sunday night is classically the most likely time any transmitter of any type will be off the air for service.)

So he asked me to clarify the details, and here's what I got:

Yes, 2.1, called WBBM-HD, broadcasts on channel assignment 3.
Yes, WBBM-HD will move away from channel 3.
In the first few months of 2009 it will move away. It's on 3 until then.
They do not know what channel it will move to, and can't even say if it will move to a UHF or a high band VHF channel.
Yes, they often have complaints from people who can't get the station, and it is usually because they are using a small antenna that is not designed to receive channel 3 (the illustration in Post 7 is typical of what won't get channel 3).
They always have to tell these people that they need to get the bigger old-fashioned antenna to get their HD station.

This cures people's problems.

So I'd like to recommend that while every installer on this site is a freekin' genius, and most DIYers here have a pretty good clue, we need to sharpen up the research skills and remember that a phone call to the people who know what is going on just might be a pretty decent idea!

Or, in the words of one of my clients:

Ask the horse.

One other point is that signal propagation is affected a lot by climate conditions, so for example stations you have been receiving OK during the summer months can have a reduced signal strength in the winter. Even UHF antennas have some minimal capability to receive VHF signals if the signals are very strong, maybe the signals are weaker now than they were, hence no reception.
Also according to the FCC web site WBBM is probably going to channel 11 in 2009 so it will still be VHF but VHF-hi which does not need such a large antenna.

This is probably not a factor in this case, as he is three miles from the station.


The station engineer says they have not changed their transmission strength.


No, it doesn't, but until the FCC sells off the VHF low band, I don't think we will find a UHF/VHFHi band antenna. Someone will probably make one, though, if other markets have most of the HD stations in the UHF range while some are in the VHF high band. Though the UHF antenna shown above is not designed for Channel 11, it will probably pick up a frequency that high, three miles from the tower, with enough strength to appear.

The question is, is it worth waiting two years to find out, or is it simply better to put in a small VHF/UHF antenna now? I'd put in the antenna now.

UPDATE TO PROBLEM

So I've been to the house twice since the last post. The first time I went onto the roof and found out that the antenna is a UHF/VHF antenna. So I first hooked the antenna up to the system straight from the antenna. It works perfectly. So I decided to try and replace the diplexers and see what happens. Put two new diplexers into the system and it works without any problems. About a day later got a call and it not working. So I go back to the house and see what is going on. Replace the diplexer on the roof and watched the system for a while and all of a sudden CBS goes out again. So I ran a new wire to the dish. Now hopefully it continues to work with out a problem. Some might ask why I waited so long to run the cable. Well the main reason is because it is a forth floor apt (Walk up) in the city and not the easiest to run.

Anyways. Thanks everybody especially Ernie for the help.

You're totally welcome, and there is usually no reason to suspect the cable. It's the simplest most robust thing about the entire system! Suspecting the cable first is sort of like having an acceleration problem with a car and first inspecting the gas pedal.

I've been there, but in my case the defective wire was installed with an F81 junction 18" above the ground and directly in the path of a sprinkler. When I disassembled it, there was no center conductor left. You just don't think of the cable as a problem.

I had to install two new diplexers in my attic recently, and was intrigued to discover that some are marked for "Interior use only", and some OK'ed for exterior mounting. I guess I'd been assuming all diplexers were created equal.

So it's possible the diplexer on the roof was NOT exterior-mount approved, which meant the weather/humidity would degrade it over time, with some taking MORE time to degrade than others. I can also imagine how certain frequences (VHF) would degrade first while others (UHF) still worked.

I had a 2-in/2-out grounding block screwed to the side of my house when I first moved in, to take the 2 feeds from my dish and ground them before running them into the attic. The first one I put up eventually rusted, and I only realized it because my SAT signal strength got worse and worse. Of course I replaced it with a new one, and fortunately that one appears to be weatherproof.

Usually the external ones have the back panel soldered on but the internal ones only use a transparent glue. Which, now that I think of it, looks more like hot glue than any other glue I can think of.

Let me add a wrinkle to the problem. I too live in 60614 zip code. I have DirecTV but use my off air HD antennae for local channels. I got 2-1 (HD) on 2 of my HD receivers (Hughes HTL-HD and the TIVO HR10-250) that were installed at the same location. My TIVO crapped out on me so I put the HTL-HD receiver in it's place. Both received 2-1 just fine. I just replaced the HTL-HD with the DirecTV HD DVR HR20-700S 2 days ago. I no longer receive 2.1 with this receiver. I do receive 2-1 on other HD receivers in the house (HR10-250 installed in another location).

All things being equal (cabling, location, etc.) 2 receivers got 2-1 and one did not.. The one that does not get 2-1 does get all the other HD local channels.

Any ideas?

Yeah. Swap the receiver that does not get 2-1 with one that does get it, and don't do any channel searching, just to verify for sure that the problem is that 2-1 is not present or strong enough at that last location.

If the problem moves with the receiver, that's pretty weird. If it stays with the room, then your 2-1 signal is not strong enough or totally gone. It would be time to look at the cable connections.

Do you get channel 2 analog at that location? If you also don't get that channel, look at this:

One odd intriguing cable connection problem might be at fault here: too short a lead on an F connector. I once had this problem in a store. Channels 2 - 5 were horrible, 7 on up were just great. After just sitting with my eyes closed, I realized that the antenna signal was looking like it had a high pass filter on it. What is the simplest high pass filter? A capacitor. What the HELL could be in my antenna system (I built it) that would act like a capacitor, since I sure hadn't put any in? A capacitor is two conductors separated by a short space, usually a non-conducting solid but also sometimes air. The only thing I could think of was an F connector with a copper lead coming out of it that was just the teeeniest bit too short to physically come in contact with the jack.

Sure enough, I found such a connector, redid the plug, and all channels were back.

I think you will find that 2-1 is one of the channels the HR20 does not receive properly. Go to [Link: dbstalk.com] to check on missing channels and those where there appear to be guide problems.