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UHF/VHF how do I know?

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Old 12-21-2010, 06:35 PM   #1
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Default UHF/VHF how do I know?

Hello,

I just moved and found an antenna in my attic. I am going to try to use it instead of getting cable, etc. But I can not find a name or and identification on the antenna. How do I know if it is VHF or UHF or both?

I guess I will just hook it up and see what happens.

Maybe someone will be able to tell me when they look at the attached pictures.

The antenna was just sitting there, but was not hooked up to anything. I wonder if it even works.
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File Type: jpg DSCF0003.JPG (122.1 KB, 32 views)
File Type: jpg DSCF0004.JPG (120.1 KB, 29 views)
File Type: jpg DSCF0005.JPG (118.1 KB, 31 views)
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Old 12-21-2010, 08:46 PM   #2
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Probably both.

The big parts pull in VHF and the small parts do UHF (or is it the other way around...I can never remember).
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Old 12-21-2010, 11:36 PM   #3
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I've never seen an antenna with the VHF (long) elements swept backwards as these appear to be, they are usually either perpendicular to the center boom or swept slightly toward the transmitter.

Is there some sort of lock to hold them in that configuration or could they have been oriented the other way or perpendicular?
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Old 12-21-2010, 11:51 PM   #4
A couch and an HDTV to go please.
 

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Quote:
Originally Posted by jim5506 View Post
I've never seen an antenna with the VHF (long) elements swept backwards as these appear to be, they are usually either perpendicular to the center boom or swept slightly toward the transmitter.

Is there some sort of lock to hold them in that configuration or could they have been oriented the other way or perpendicular?
You are correct. They should be perpendicular, but I could not get them in the picture and they were hitting the furniture in the room. So, yes, they should be perpendicular.
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Old 12-22-2010, 07:05 AM   #5
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Originally Posted by DoctorCAD View Post
Probably both.

The big parts pull in VHF and the small parts do UHF (or is it the other way around...I can never remember).

The higher the frequency, the shorter the element. UHF is shorter.
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Old 12-23-2010, 10:03 PM   #6
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I finished installing the antenna. But the signal is worse than the rabbit ears I was using. I get a maximum signal strength of 70 out of 100 (at best). So I am not sure what I am going to do next. It took two days to install this thing. They say you lose 50% of you signal by putting inside the attic.

My pictures just freezes. Sometimes it goes blank. Its really bad.

I have the antenna, connected to a 300 Ohm to 75 balun, connected to a 6 foot cable, connected to a 3 way splitter, connected to there 25 foot cables, connected to the three TV's. And the pictures sucks.

VHF comes in pretty good, but the UHF channels are bad. Maybe this antenna is a VHF only. Should I be pointing the short elements toward the station or the long elements towards the stations. Basically I don't know which end it the front. I currently have the small elements pointing to ward the station.
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Old 12-23-2010, 10:40 PM   #7
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It looks like a VHF/UHF antenna, since it has groups of longer and shorter elements. The end with the smaller elements points toward the stations. How far are you from your stations? Can you post your TVFool report, so we can help you more? Have you tried temporarily taking out your splitter and trying it out on just one tv? Does your attic have any significant metal material (such as aluminum siding or foil insulation that would reduce signals too much? Is your antenna mounted at the highest point in your attic?
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Old 12-23-2010, 10:53 PM   #8
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I have attached the TVFool report. Let me know if you can't read it.

I am only 5.9 miles away from the stations I watch.
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Old 12-23-2010, 10:59 PM   #9
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Originally Posted by gcd0865 View Post
The end with the smaller elements points toward the stations. Have you tried temporarily taking out your splitter and trying it out on just one tv? Does your attic have any significant metal material (such as aluminum siding or foil insulation that would reduce signals too much? Is your antenna mounted at the highest point in your attic?
Good. I have the end with the smaller elements pointing toward the transmitters.

I have not tried removing the splitter and just attaching one TV, but I was going to try that tomorrow.

The attic is very small, you can't even sit up in it very well. But I could not see any foil insulation, etc. The sides of the house is brick all the way up to the roof. Yes, I am at the highest point of the attic (just above the second floor).

Thanks...
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Old 12-24-2010, 09:23 AM   #10
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Default Don't give up yet

I wouldn't give up yet. Your numbers look strong.

I'm no expert like some of the guys here, but I would methodically start checking connections (and replacing if necessary) and eliminate that splitter- replacements are cheap if needed- to see if things improve. One bad connection could be your entire problem, but there is no way to tell without taking each apart individually and examining it.

Look for corrosion of the connector or the foil / woven liner of the coax touching the center conductor at any point inside the connections.

I had an issue with one of the runs in my satellite install where the signal was garbage. Once I redid the offending connector, there was an immediate 100% improvement. All because the conductors were touching inside the F-connector. The connections are not hard to make, but they have to be done right to pass a good signal.

Edit to add- your UHF might improve if you line up all of those front elements so that they are perfectly parallel to one another. Some of them look like they've been knocked around a bit. I've been reading up on antenna theory a little lately and having those elements parallel will go a long way to passing maximum signal through the transformer into your cable.
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Old 12-24-2010, 09:40 AM   #11
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I did a check this morning. On channel 6 (VHF) I am getting a 87/88 on the signal meeter. Its coming in good and does not freeze or break up. So VHF is working fine. I even get channel 12 now. Also VHF. But the UHF channels do not come in good.

So I am thinking I have a VHF only antenna.

I also checked the signal strength of channel 29.1 (uhf). The signal strength is about 50 and the screen is blank. It needs more than 50% to even give you a bad picture.

At 60% I get a picture, but is breaks up and freezes.

The fact that channel 6 (and all my vhf stations) is coming in good, would that mean I don't have a problem with my wires? and I really just need to figure out what is wrong with the UHF signals?
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Old 12-24-2010, 11:02 AM   #12
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Default Vould be only VHF

Looking at your TV fool report, some of the "virtual" channels for the majors are in the VHF band. But some of them are actually broadcasting on the UHF band. For instance, your CBS is virtual 3 (vhf) and real 26 (uhf).

Stations broadcast with virtual channels because they had an identity by channel number prior to the DTV changeover. It looks like the big 3 and PBS were ALL VHF prior to the switch and now some of them are broadcasting on UHF.

So I would say it is quite possible that the antenna you found is VHF only since it would have been sufficient to get the major networks and PBS prior to the switch. And if the VHF is coming in that strong behind a brick wall in the attic, I would certainly doubt that any of your connections or splitters are causing problems.

You can easily add a UHF antenna to that setup in the attic and get everything then. It's easy to combine the signals and run them in on your existing cabling. Lots of posts around the net about building your own UHF out of coathangers and scrap lumber. If you feel like messing with it, might be a fun experiment. I would think it ought to work easily since you are so close to Philly and the towers. I am going to be building my own VHF Yagi and UHF 4 Bay next week while I'm off, just for kicks.

If you don't feel like messing with it, you could get a commercial UHF and combine its signal in.

Last edited by wmshay6; 12-24-2010 at 11:07 AM.
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Old 12-24-2010, 11:19 AM   #13
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Quote:
Originally Posted by wmshay6 View Post
You can easily add a UHF antenna to that setup in the attic and get everything then. It's easy to combine the signals and run them in on your existing cabling. Lots of posts around the net about building your own UHF out of coathangers and scrap lumber. If you feel like messing with it, might be a fun experiment. I would think it ought to work easily since you are so close to Philly and the towers. I am going to be building my own VHF Yagi and UHF 4 Bay next week while I'm off, just for kicks.

If you don't feel like messing with it, you could get a commercial UHF and combine its signal in.
How do I combine signals? Do I just get another 2 way splitter and run it in reverse, so instead of splitting, it is actually combining? Then I could just get a UHF antenna and add it to my already installed VHF antenna.

I did try to make an antenna out of coat hangers, but it did not work very well.
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Old 12-24-2010, 11:41 AM   #14
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Is this the way to I should hook it up? Please see attached diagram.
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Old 12-24-2010, 01:03 PM   #15
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Your diagram looks good but, you need a uvsj to join the uhf and vhf antennas rather than a 2 way splitter. See: http://www.solidsignal.com/pview.asp...Combiners&sku=
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