Got a TV antenna question

bigcozy

bigcozy

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Since almost everyone has cable or dish, this may be hard to answer. On my boat I just have a TV with rabbit ears. About a month ago, I started getting cable channels like ESPN. They weren't coming in very good, but about as good as the normal channels I get. Two questions:

1. Why am I getting them?

2. Can I buy a good antenna to get these better?
 
Nitroz

Nitroz

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1. Dunno? It is however, very interesting. :) Wireless cable tv, COOL!
2. You can definitely find a better antenna.

What type of tv is this? Does it have an HD tuner or is it just your standard plain tv?

Is the "Southern Fried" location Georgia? :laughing:
 
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Sub_Umbra

Sub_Umbra

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1. Don't know.

2. Since your TV is already dealing with them, yes. However, the first, simplest, cheapest thing I would try would be to buy a broadband inline FM amplifier (for use with TVs) and see what happens when you jack the weak signal up 10 db or so. The wonderful Ramsey Elecronics used to have a broadband amplifier kit for cheap that ran on a 9V, I think. They probably still do.

If you can get them at the dock (where you have access to an AC shore line) you might want to try an AC broadband FM amp from the Rat Shack before going to the trouble of ordering and building the Ramsey kit.

Be sure to post again to tell us what you did and how it worked.
 
B

BB

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If the channels you receive are the same as the local cable system, then there is an RF "leak" by the cable company somewhere...

It is also very possible that if you are in a wet (and or salt water environment), that a boat next to yours has a corroded cable connection...

A better directional/amplified antenna will help (until they fix their problem).

-Bill
 
A

ABTOMAT

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You've discovered the secret they don't want you to know. Hired killers are tracing your email as you type.


:)
 
S

scott.cr

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I wonder if someone is rebroadcasting their cable connection to a secondary TV? Or maybe it's a frequency image?

Interesting. You need a Ham megageek with some gear to help you out. ;-)
 
Brock

Brock

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Actually I have heard of Marinas retransmitting the cable signal with a low power transmitter so all of the boats could receive it without running cable to all the docks or at moorings. I thought I heard they were doing a similar thing in some RV parks. Maybe this rumor is true?
 
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bigcozy

bigcozy

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I am not in Georgia

No way my marina is broadcasting, although that is a good idea. I don't know of any boat that has cable hooked up, most have sat dishes, and the channels I am getting exactly correspond to local cable. I have seen wierd things happen in terms of electonic stuff moving around in water, and it is possible that the water is acting as kind of conductor, but, my boat is fiberglass. This is also fresh water. The rebroadcasting to a second TV makes some sense. My boat is 40', but some of these monsters are 90'+ and may have some set up like that. If you drop a few million on a boat, you are going to want up to date technology. I have shore AC, I also have a 10KW generator with invertors, I can run anything I need to either way. I am going to study my options and maybe try some boost like suggested. My TV is about a year old, flat screen, not sure if its HD ready but I doubt it. Any more thoughts appreciated.


The irony here is I almost never turn on a TV except during bad weather.
 
T

teststrips

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what station are you tuning this on? OTA (over the air) TV baisically comes in two forms - UHF and VHF. Very High Frequency 30-300mhz - Ultra High Frequency 300mhz-3ghz - both "bands" are broken down into several sections each used for differennt uses... here are the frequencies for TV

VHF
54–72 MHz: TV channels 2-4
74–80 MHz: TV channel 5
81.5–87.5 MHz: TV channel 6
174–216 MHz: TV channels 7 through 13, and professional wireless microphones (low power, certain exact frequencies only)

UHF
470–512 MHz: TV channels 14–20, public safety
512–698 MHz: TV channels 21–51 (channel 34 used for radar[citation needed], channel 37 used for radio astronomy)
698–806 MHz: TV channels 52–69 (to be auctioned for other uses once conversion to digital TV has been accomplished)

Baisically all you need to know is the chanel you are getting signal on - then you can get the frequecy... then buy an antenna which is designed to pull in a frequency range that includes that frequency.

You could buy an antenna that does both UHF and VHF - BUT these antennas generally have trouble with "noise" and you get a lousy picture. Same story for VHF TV antennas... most are either better with the lower 54-87.5 mhz range. or the higher 174–216 range. UHF antennas are less complex as they generally are tuned for the entire 470mhz - 806mhz range.

I Like the Channel Master line of antennas - but your local radio shack should also have antennas that will work just fine. (large YAGI antennas)
 
B

BB

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But the typical cable TV installation does not skip frequency blocks between VHF and UHF... Here is a quick chart of over the air and cable TV frequencies:

Cable TV Channel Allocation Scheme

The problem with "leaky" cable is that it can interfere with other uses as it is broadcasting outside of the normal assigned TV frequency blocks.

-Bill
 
bigcozy

bigcozy

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I know you guys like a good technical mystery and I appreciate the brain power on this board. To deepen it, rainy last two days and picture almost quit. Cleared out a little tonight and picture came back. Going to go into town and pick up something from Radio Shack and see if that helps. I am now about convinced that someone is wireless broadcasting to another TV somewhere near me. The thing that still stumps is that I am almost 100% sure no one has cable out here. I will let you know when and if I solve this.
 
B

BB

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If you have a little portable TV (or radio that can receive TV and can connect it to a directional antenna), you can make a direction finder and locate the source...

Stand in one location and rotate the antenna until the signal disappears (usually it is easier to hear a null than a peak volume point). Draw a line 90 degrees to where the antenna is pointing (either on a map, or in your mind).

Go a few blocks (or a few hundred feet or yards if the source is near by), and do it again. Where the lines cross, will be your source.

Check for other TV cable frequencies too... Also, if you TV supports it, try both the "CABLE" and "BROADCAST" settings and see if you find other stations above VHF (chan 13) on the Cable setting--obviously if you get the other CATV channels (on the correct channels)--it is probably cable TV rather than somebody just mixing/down converting from some other source...

By the way, if you can RDF with a TV/radio, it works surprisingly well. Decades ago I helped our local airport manager try to find an emergency locator that was stolen from a local plane (probably by kids) and was being turned on once in while. And they were obviously watching as the airport fire truck was trying to use a hand-held RDF trying to find the source.

Well, the crew was sure that the kids were hidden in the hills behind the airport and kept heading out the "radial" to try and find them (no luck—for weeks).

Well, I was there one time when the kids turned the ELT on and helped by ignoring the airport manager and did the two measurements just visually--The two lines crossed in a residential area about 1 mile away from the center of the airport (opposite direction). Hopped in the truck and told them where to drive. Pulled out the RDF again (about several hundred feet from where I thought they were among about 5 homes), and in about 3 seconds the signal went dark and they never turned it on again...

-Bill
 

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