HDTV reception works on some TV's, but others.....

[riverpine]

I tried to figure this out and I'm stumped.

Short and sweet version: HD antenna (no cable or sat.). Antenna line is split: one split works fine on the main HDTV - all of the expected channels come in fine. One split goes to a DVR right next to the HDTV. Some of the channels work, but some several are "blue screens." The DVR is the same distance from the antenna that the working HDTV is located. One other split goes under the house and comes up elsewhere. I get the same "blue screens" on the same channels as the DVR.

To make it even more wierd, before the official final HD transition date, I got all of the channels on both TV's and the DVR. But when the final deadline passed, I lost several channels.

Any ideas?

Thanks.

[usually_quiet]

Just to be thorough, have you re-scanned the channels for the problem equipment? Some stations changed frequency post-transition.

Also tuner sensitivity varies. Some of your equipment may have a better tuner than others. Some stations reduced their signal strength post-transition or aimed it in a slightly different direction.

As an example, where I live, one broadcaster that I was already viewing using its digital channels prior to the transition went from using a 1000 kW transmitter to a 9.8 kW transmitter and changed its frequency from the UHF band to the VHF band.

[riverpine]

I have rescanned to no avail.

Would an amplifier after the split that goes to DVR and second TV help?

Thanks.

[usually_quiet]

Since one TV can pick up the signals, an amplifier might help, but I am not sure about the placement. I use rabbit ears, so someone more familiar with setting up outdoor antennas could probably provide more useful information.

However, based what I know about amplification in my own situation, if some of your stations have powerful transmitters and are located within 10 miles of your home, then an amplifier might make your reception worse for those.

[freebird73717]

The more splits you have the less signal strength you have. And like usually quiet said some tuners are better than others. Thats why your tv gets channels and your dvr's don't. The tv has a better tuner that can get a picture from a lower signal. The cheap indoor amps may or may not work. For me it didn't work. The amp actually increased the line noise and knocked reception of one of my channels off. You would have better luck with a pre-amp on the outside pole rather than one of the cheap amps that you place in your house.

something like this
http://www.solidsignal.com/pview.asp?mc=03&p=CM0068DSB&d=Channel-Master-CM-0068DSB-VHF...28CM0068DSB%29

[Steve Stepoway]

If you need to amplify your signal (and it sounds like you do -- I had a similar problem), you want to amplify the best signal you have, and that's outside at the antenna. Put a pre-amp out there, as freebird73717 said, and bring the amplified signal down to your splitter. If you amplify after the splitter, you are amplifying a garbage signal, and you will get stronger garbage. But it will still be garbage.

Steve

[edDV]

At a more fundamental level, run your location through http://www.tvfool.com/?option=com_wrapper&Itemid=29
to find out what exactly happened on transition day.

Post the results here and I'll help you analyze it like I did in this thread.
https://forum.videohelp.com/topic369292.html?highlight=antenna

[riverpine]

Here's the link TV Fool provided:

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d8ecd16c2fca07b


Thanks for whatever help you can give.

[riverpine]

Would this pre-amp work, too? The one suggested earlier is out of stock.

http://www.solidsignal.com/pview.asp?mc=03&p=ANC7778


Thanks.

[edDV]

Here's the link TV Fool provided:

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d8ecd16c2fca07b


Thanks for whatever help you can give.

Which are the channels that come in on the main TV but not on the others?

What is your antenna model and how is it mounted? Is it pointed ~178 degrees (magnetic)?

Note that WWBT (NBC) is on VHF channel 12* and at 165 degrees. Alternate WVIR (NBC) is at 295 degrees. Either may need a separate antenna.

Also note that WUPV (CW) is at 113 degrees.


*The temportary digital channel for WWBT was on channel 54 (UHF). They changed to VHF channel 12 in June.

[riverpine]

12 and 23 don't come in on the non-main TV.

The antenna is mounted in the eaves of the attic. I'm not sure which direction it's pointed.

What's the significance of 12 (WWBT) now being a VHF instead of UHF? This is the main channel that's a problem. We had no problems before, but do now (but still don't have a problem on the main TV).

Thanks.

[edDV]

12 and 23 don't come in on the non-main TV.

The antenna is mounted in the eaves of the attic. I'm not sure which direction it's pointed.

What's the significance of 12 (WWBT) now being a VHF instead of UHF? This is the main channel that's a problem. We had no problems before, but do now (but still don't have a problem on the main TV).

Thanks.

VHF (Ch 7-13) is in a different frequency band and requires a different antenna design. You may be able to solve the problem with a different antenna and proper pointing. Is your current antenna UHF only? Model number?

PBS WCVE (virtual 23, actual 42) should be equal strength to ABC, FOX and CBS.

[riverpine]

I tried to find a model # on the antenna, but I couldn't find one.

As I recall, I bought it from Radio Shack and it looks like this one:

http://www.radioshack.com/product/index.jsp?productId=3808570

Thanks.

[edDV]

I tried to find a model # on the antenna, but I couldn't find one.

As I recall, I bought it from Radio Shack and it looks like this one:

http://www.radioshack.com/product/index.jsp?productId=3808570

Thanks.

That model is dual VHF (longer horizontal elements) and UHF (the V and directors).

Attic mounting typically cuts signal strength by 50% or more so 24 miles for WWBT is marginal and inadequate for 45 mile WVIR.

First make sure your antenna is pointed ~ 165 to 178 degrees (magnetic compass). An antenna mounted pre-amp may make the difference at that distance but a larger antenna would be a better start. The larger the antenna, the more the gain and directivity. Idea is to get signal strength up so it can be split to the three ATSC tuners. Each 2 way split will cut the signal 6dB (50%).

[edDV]

Would this pre-amp work, too? The one suggested earlier is out of stock.

http://www.solidsignal.com/pview.asp?mc=03&p=ANC7778


Thanks.

Yes that is the correct type of preamp.

[riverpine]

Can you forward a link for the type (size, etc.) that you'd recommend instead of the type I have?

Thanks again.

[edDV]

Try pointing your existing antenna first.

There are many. Depends what fits in your space.
http://www.summitsource.com/outdoor-antennas-uhf-vhf-tv-antennas-c-47_57_58.html

Wineguard has an HD 769 line that is upper VHF and UHF only. These have less width.

http://www.summitsource.com/winegard-hd7694p-digital-high-definition-vhfuhf-hd769-seri...le-p-8353.html

http://www.summitsource.com/winegard-hd-7695p-digital-hdtv-high-definition-vhfuhf-hd76...le-p-9388.html

Also 7696 to 7698 for deeper fringe.

[riverpine]

So bottom line (I've already taken too much of your time!)....would you recommend trying a pre-amp first? If it's still not right, then upgrade to a better antenna? Or would the pre-amp be wasted money if I ended up with an upgraded antenna?

Thanks for all of your help.

[edDV]

If space is tight, point the antenna first.

Then try the preamp (with return possible).

If that doesn't work get the larger antenna.

I'm trying to make this answer general. You are in a suburban area with low multi-path interference so an amp may help. Closer in, a higher directional antenna may be more important than amplification to reduce multi-path interference. Farther out you would need both a large directional antenna and a preamp.

[Nelson37]

Just for giggles, try moving the 3rd-split tuner, temporarily, to the first-split location and test it there. If that works, you may simply be able to resolve the issue with better-quality cable and splitters. i was truly amazed at how sensitive reception is to such semmingly minor components. I have one cable with a joiner in the middle, about a half-turn either way will lose a channel.

I had a similar issue where several weeks after the final digital change-over, one station that had been coming in just fine simply disappeared. In my case it happened on two different antennas and tuners. Obviously they either reduced power or moved the tower. Re-orientation was no help.

Moving soon so haven't tried a new antenna, hopefully my new location may get better reception. Unfortunately, external mounts are frowned upon by most landlords as I am in a hurricane-prone area.

[edDV]

Yes, I agree. Also look at a 3x1 splitter instead of daisy chaining 2x1 splitters. A 3x results in 33% to each where chained 2x1's do a 50% signal reduction each time. The second and third tuners get a 25% strength signal.