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Old 03-04-2015, 10:27   #1
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TV reception aboard simple

Just finished making and installing a simple bi-polar antenna on my Cal 27 sailboat. I get 14 free digital channels in Belhaven, NC. My flat antenna similar to ones advertised on TV just gets 3 on a good day. Go to Radio Shack or similar and get an indoor/outdoor matching transformer for 300 ohm screw terminals to 75 ohm coax connector. Also purchase 6 feet of 1" x 1/16" or 1/8" aluminum. I used 1/8" for strength. Cut two pieces 26" long. Bend each piece around something, I used a pool chemical bucket, so the two pieces form a circle. Use two pieces of Starboard, or similar, 2 1/4" 3" to join the two half circles of aluminum, keeping the ends at least 1/8" apart. 1" 1/8" ss bolts, 8 of to make solid joints. Make a cross piece roughly 17" plus 1" bent at 90 degrees at each end to bisect the circle. The starboard is wide enough so no touching of other aluminum when bolting together. Attach a piece of 1/2" or more pvc about a foot long through bolted to the crosspiece so when it is verticle, the aluminum circle is horizontal. Drill a hole at each end of pvc for hoisting up high with paracord or similar. Attach wire leads of transformer , one to each half of aluminum circle by using bolts through starboard. Attach long coax cable and hoist it up as high as possible and tie off hoisting lines from top and bottom of antenna. NO pull on coax. Connect to TV, do channel search and set up. Number of channels depends on area where you boat.
Enjoy. sailordaveb@yahoo.ca

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Old 03-04-2015, 14:51   #2
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Re: TV reception aboard simple

Got a picture?
Thanks


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Old 03-04-2015, 20:03   #3
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Re: TV reception aboard simple

No pictures yet. Will try to get one soon. Just below my spreaders so have to lower for pic. Very happy with it.

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Old 03-04-2015, 20:10   #4
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Re: TV reception aboard simple

Yes photos please. I would also be interested in seeing your project.
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Old 03-04-2015, 20:21   #5
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Re: TV reception aboard simple

Some guy at a local flea market was selling a similar sounding HDTV antenna for $25. Would like to see a picture of yours as it doesn't sound like it could be made and sold for that little. He apparently makes them and sells them at flea markets.....
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Old 03-04-2015, 20:21   #6
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Thumbs up Re: TV reception aboard simple

I use a car diversity tuner with two antennas
Small whips & this works well for me, will even work
at sea or on a mooring with boat turning no
adjustment nesacary
The are relatively cheap about $100
Google DVB-T car TV tuners
Some have as many as 4 antennas
They are 12v & come with a remote
If you buy one make sure it will decode
MPEG 4 as I expect this to be the next
TV codec.
This should ensure you are future proofed.
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Old 04-04-2015, 09:42   #7
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Re: TV reception aboard simple

Quote:
Originally Posted by BriaF View Post
If you buy one make sure it will decode
MPEG 4 as I expect this to be the next
TV codec.
This should ensure you are future proofed.
Digital TV is broadcast over VHF and UHF frequencies. MPEG 4 is a digital multimedia format used to store video and audio files and used by some multi-media players. It is also used to decode some satellite and cable TV broadcasts in receiver boxes. These codecs are built into the receivers, whether they are for satellite, cable or your built in receiver in your TV set. I don't see any way this will affect over the air broadcast antennas, but perhaps I missed something. Chuck
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Old 04-04-2015, 10:28   #8
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Re: TV reception aboard simple

Try a home built Fractal antenna, here's some interesting antenna stuff for digital TV. A fractal antenna is used inside a cell phone, that's helped them get so small. Basically taking an ordinary bow tie antenna and making it smaller. I use the bow tie now and am happy with it. The fractal applied to the elements allows two things, it increases the bandwidth, for TV that's a good thing, since the bow tie basically is tuned for one frequency, at the same time it reduces the gain at the center frequency but helps the off frequency signals (That's increasing the bandwidth, good for multiple TV frequencies) and it make the elements smaller in total size, so the antenna might fit someplace better, like taped to the side of a wooden sailboat mast, that's in my future. Here's a couple articles about them. Making a Four Iteration Koch Fractal Antenna for HDTV/DTV with Copper or Aluminum Foils, Part 1 of 2 How to make a fractal antenna for HDTV / DTV plus more on the cheap-/
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Old 04-04-2015, 11:36   #9
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Re: TV reception aboard simple

Quote:
Originally Posted by Opie91 View Post
Yes photos please. I would also be interested in seeing your project.
+1... think I could use that...
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Old 04-04-2015, 13:22   #10
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Re: TV reception aboard simple

Here's my bow tie that I use to get 25 digital channels about 35 miles east of Ft Myers, Fl. I hook up ordinary TV coax and wind about 5 loops of coax about 5 inches in diameter to make a balun. The antenna is balanced, signal comes in on both sides equally, the coax and TV wants all the signal just to flow on the inside conductor, thus uinbalanced, the 5 loops of coax up near the antenna connection makes a coil that tends to block electric flow on the outside conductor, but not block the sheilded inner conductor, this forces most of the electric flow to the inside conductor. Balun = balanced unbalanced.
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Old 04-04-2015, 16:44   #11
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Re: TV reception aboard simple

Hope the attached picture works. Dave
The antenna is just below the spreader suspended on a loop of paracord so it can be put up or down easily.

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Old 04-04-2015, 17:52   #12
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Re: TV reception aboard simple

Quote:
Originally Posted by AnchorageGuy View Post
Digital TV is broadcast over VHF and UHF frequencies. MPEG 4 is a digital multimedia format used to store video and audio files and used by some multi-media players. It is also used to decode some satellite and cable TV broadcasts in receiver boxes. These codecs are built into the receivers, whether they are for satellite, cable or your built in receiver in your TV set. I don't see any way this will affect over the air broadcast antennas, but perhaps I missed something. Chuck

BrianF may be in a country that has DVB-T. The T is for terrestrial. All digital TV systems use MPEG4 for video encoding. But they all don't use the same bit rate and resolution. Also, the audio standards are different between US and rest of world.

The real difference is the channel coding and RF modulation. DVB uses frequency division multiplex aka COFDM. In the US the standard is a single sideband modulation known as VSB. So you have to get a receiver that has the right formats for your country of choice.

The U.S. is going to implement a mobile TV system which is not compatible with existing receivers within a few years. But new receivers will be pretty cheap. Free over the air TV is one of the best kept secrets around. Most major cities in the US have 30-60 channels free.
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Old 04-04-2015, 17:58   #13
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Re: TV reception aboard simple

You do not need any of that fancy stuff. I have been using vertical dipoles for years and get excellent digital TV reception in some pretty remote places.

The one I have at the moment is made from 5 red been cans inside some 4" poly pipe with a coaxial cable down inside the mast. I used the red been cans to get better tuning over a broader range of frequencies.
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Old 05-04-2015, 07:25   #14
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Re: TV reception aboard simple

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BrianF may be in a country that has DVB-T. The T is for terrestrial. All digital TV systems use MPEG4 for video encoding. But they all don't use the same bit rate and resolution. Also, the audio standards are different between US and rest of world.

The real difference is the channel coding and RF modulation. DVB uses frequency division multiplex aka COFDM. In the US the standard is a single sideband modulation known as VSB. So you have to get a receiver that has the right formats for your country of choice.

The U.S. is going to implement a mobile TV system which is not compatible with existing receivers within a few years. But new receivers will be pretty cheap. Free over the air TV is one of the best kept secrets around. Most major cities in the US have 30-60 channels free.
That all very true, but has nothing to do with the antenna, which is what we are discussing and which is what I pointed out was incorrect in one statement. The antenna does not care what format the receiver uses. Chuck
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Old 05-04-2015, 07:36   #15
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Re: TV reception aboard simple

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.............. The antenna does not care what format the receiver uses. Chuck
Correct. A lot of people don't understand this and the companies that advertise "digital antennas" are preying on that ignorance.

As for the homemade antennas described or pictured, you can't build an antenna better than one you can buy. If money is tight, you can assemble a concoction of coathanger wires or bicycle wheels that will pick up a signal and pat yourself on your back thinking you have saved $100 but the commercial antenna would have worked better and certainly looked better.
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