Questions about one channel

[rickyp816]

Hello,
A few months ago I set up a HTPC with a Hauppagage dual tuner (2250), with a Winegard HD-1080 antenna mounted to a mast on the 2nd story of my house. The signal is split to also drive a basement TV, which works just fine with those stations as well. Everything seemed fine and I was getting PBS, Fox, ABC, NBC, and CBS very well. NBC would pixelate and occasionally cut out a bit, but it was acceptable.

Fast forward to now, we've been having more and more problems with NBC, to the point where it dropped completely for almost a week. Other channels were also starting to come in a little worse. Looking into the specs of my antenna further and realizing I'm splitting it 3 times (basement, each tuner for HTPC), I thought I'd try a better antenna.

I bought a Winegard HD7694P as it has higher overall gain. Hooked that up and all the channels are coming in much stronger (back into the 4-6 of 6 bar range on the PC and 70-90 on the basement TV). The odd thing is, PBS, which is closest and strongest, is now very weak (1-2 bars on PC, 9-35 on the basement). Even if I aim the antenna directly at PBS, it's very weak (and the other stations suffer). I did notice on the basement TV the signal would bounce from almost 0 to 35-40 (out of 100) quickly - it was all over the place.

I'm confused - if it were multipath, wouldn't it improve if it were pointed right at the station? Could it be too strong vs. the other channels? Would I be better off keeping the old antenna and adding a preamplifier (such as Winegard AP-8700)?

I'm at the bottom of a slight hill, the area is suburban with a fair amount of tall trees. I appreciate any advice!

http://www.tvfool.com/?option=com_wr...8d17f3cac9a4f1

[GroundUrMast]

I presume when you indicate PBS, you are having trouble with WGVK. They are one of the few TV stations in the country to broadcast DTV in the low VHF band. Channel 5 in this case. Neither of the antennas you have are designed to receive the low VHF channels (2 - 6). As you have experienced, an antenna will still receive some signal on frequencies it's not designed for.

Antennas Direct and Antennacraft each offers a L-VHF antenna, model V4 and model Y526. These antennas are specifically designed to receive channels 2 through 6.

As the leafs start to come out, you will see signal levels drop. The HD7694P should be able to provide the gain needed to offset that loss. The additional gain on channel 7 should have stabilized reception of WOOD presuming it is aimed in that direction.

You will need a HLSJ.

Edited: As ADTech points out, most HLSJs will pass UHF through the high port. Thanks ADTech.

[ADTech]

You will need a HLSJ and a couple of UVSJs.
Attached Files
File Type: pdf Low VHF combining into H-VHF and UHF.pdf (19.5 KB, 0 views)
__________________

The circuit in that diagram is unnecessarily complex. You don't need any UVSJs.

Use ONLY an HLSJ to combine the low-VHF antenna to the 7-69 antenna.

[rickyp816]

Thank you GroundUrMast and ADTech for the quick reply and links. It's appreciated! If I understand, basically the new antenna isn't as good with low VHF as the old one?

I assume since my HD-1080 picked up Channel 5 reliably (6 of 6), I should be able to use that as the "low" portion of this dual antenna scenario?

ADTech, wouldn't the HLSJ filter out any UHF signals from the 7-69 antenna? That's why I thought you'd use the UVSJs. If I'm wrong, I can certainly try without them, but just want to make sure.

[GroundUrMast]

ADTech is right. Note that I have edited my previous post.

I would not criticize the HD7694P for not receiving frequencies outside it's design range, that is actually a desirable characteristic that reduces interference in the designed frequency range.

If the 1080 receives enough signal on channel 5 to be reliable, use it.

[ADTech]

ADTech, wouldn't the HLSJ filter out any UHF signals from the 7-69 antenna?

No. It's just a diplexer with a transition frequency around 100 to 110 MHz. The high-pass filter on the "H" port passes all frequencies above the cutoff (transition) frequency with very minimal insertion loss. It does not have any upper limit on its pass band.

[rickyp816]

Great - thank you both very much. I hope this solves my problem!

[John Candle]

Read and understand this about , Real Digital Tv Channels , Virtual Digital Tv Channels , Analog Tv Channels , http://forum.tvfool.com/showthread.php?t=695 . The Tv transmission and reception channel bands are VHF Low 2 thru 6 , VHF High 7 thru 13 , UHF 14 thru 69 . Here is a Tv antenna that is design to receive all 3 Tv channel bands Winegard HD7082P.

[John Candle]

Here are some free online Tv guides , www.titantv.com , http://television.aol.com , http://zap2it.com , http://tv.yahoo.com , http://tv.entertainment.excite.com , http://www.tvzap.com