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Old 10-Feb-2017, 12:42 PM   #1
VTME09
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Has anyone made a 300 ohm twin lead antenna?

Has anyone made one of these antennas for a single channel from 300 ohm twin lead? How well did it work? I want to get channel 3.
http://users.wfu.edu/matthews/misc/dipole.html
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Old 10-Feb-2017, 2:29 PM   #2
rickbb
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They work well enough, but how will you mount it? They need to be "aimed" at the tower so it works best up on the roof and getting it on some kind of non-metal mount will be tricky.

One of these for real channel 3 will be just over 6 feet long.

You can buy a low VHF, (assuming you mean real channel 3), antenna very cheaply, BTW.

Last edited by rickbb; 10-Feb-2017 at 2:32 PM.
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Old 10-Feb-2017, 3:02 PM   #3
VTME09
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I have seen some people have supported them in a PVC tune and was thinking about doing that and suspending it in the attic where size wouldn't matter.

I currently have a Antennas Direct High VHF antenna and it picks up real channel 3 (~50 miles away) in the winter only. I pointed it at channel 11 (5 deg mag ~50 miles away) thinking I couldn't get 3 (260 deg mag) but after the leaves fell I could. So I am expecting to loose it again come spring. My zip code is 24503.

What VHF Low antenna do you recommend? I have been looking at the Winegard HD7000R but it's only rated for 30 miles.
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Old 10-Feb-2017, 4:13 PM   #4
ADTech
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Quote:
What VHF Low antenna do you recommend?
There aren't any VHF low antennas on the market any longer so your choices are very limited. We liquidated our remaining inventory of the V4 antenna a while back, I think these guys might still have them: https://www.affordablehdtv.com/terre...8ofsvgsqj1ian2 The V4 is a cut-to-channel 4 Yagi and is effective for channels 2, 3, & 4. Not so much on 5 and poorly on 6 and FM. If you needed 5 or 6 or FM, I think our old 3FM antenna (which we also liquidated inventory of) can still be found on Amazon.

If you do add in a low-band VHF antenna, you'll still need to score an HLSJ in order to readily combine it with the rest of your setup and they're getting very scarce. I did find a listing on ebay, do a search for "CABLETRONIX HLSJ". I've not tested that particular one, but it should work based on the manufacturer's spec sheet.

Quote:
I have a Antennas Direct High VHF antenna and it picks up real channel 3
If you have the C5, it's tuned very precisely for high-VHF channels 7-13 and does a remarkable job of rejecting low-VHF and FM frequencies (it is supposed to do that by design), probably in the order of -15 to -20 dB or so on channel 3.

If you have a suitable length of 2-conductor heavy electrical wire 12-14 ga, insulated or not) and a common matching transformer (https://www.lowes.com/pd/RCA-Outdoor...former/3724168), you can easily fabricate a simple dipole without trying to find twin-lead. Use two 4'3" sections of wire attached to a simple frame of wood or PVC with a 1-2" gap between them and attach each leg of the transformer to the inside ends of the gap with a simple sheet metal screws. Aim it broadside in the direction of WBRA, then adjust for best results.
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Last edited by ADTech; 10-Feb-2017 at 9:47 PM.
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Old 10-Feb-2017, 6:13 PM   #5
VTME09
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I have a DB8E with a VHF-1 retrofit kit.

Found a 100 feet of twin lead online at Fry's, ~10$ delivered. Would the twin lead or electrical wire be better?
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Old 10-Feb-2017, 6:40 PM   #6
ADTech
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If you have a matching transformer (which you're going to need anyway) and some wire, why buy twin-lead? There won't be any difference in performance if executed properly.
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Old 11-Feb-2017, 2:01 AM   #7
VTME09
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What is the range on the Antennas Direct V4? I see two places that say 25 miles and the link ADTech sent says 55 miles.
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Old 11-Feb-2017, 1:06 PM   #8
ADTech
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It is my personal opinion that range numbers are an irrelevant but a necessary evil. At best, they're only a wild-a$$ guess. There are too many other variables that are actually more important than the antenna itself that are involved in determining if any given antenna is suitable for any given situation They're pretty much a lowest common denominator for folks for whom a mile is the only thing they can relate to.
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Last edited by ADTech; 11-Feb-2017 at 1:11 PM.
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Old 11-Feb-2017, 3:52 PM   #9
rabbit73
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I agree; mileage figures are only useful to compare different models of the same brand. What counts is how strong the signals are at your location, and putting it in the attic makes them even weaker. What good is a 55 mile antenna if you happen to have a hill five miles away that blocks the signals?
Quote:
Has anyone made a 300 ohm twin lead antenna?
Yes, the twin lead folded dipole is one of my favorite antennas.

Many years ago I was located between Richmond and Norfolk. In my attic I had a folded dipole or a 5 element single channel yagi cut for each channel. I had a 2-pole, 12 position ceramic switch with its shaft extended below so that I could select which antenna I needed. It worked very well. All the feed lines were 300 ohm twin lead, which is why I used a 2-pole rotary switch.

At my next location, I only used the Norfolk channels. I had a 4-bay UHF antenna and a folded dipole for 13 connected to the original 7777 preamp that had separate inputs for UHF and VHF. The antennas were only 5 feet AGL, but reception was satisfactory. The UHF and VHF channels were about the same strength on my report, but 13 was weaker for me because of the lower gain of the folded dipole.

At my present location I am closer to Norfolk and am able to use a GE 34792 Attic Antenna indoors at ground level. Channel 13 is again weaker because the GE antenna only has a single element folded dipole for VHF-High. The UHF section has more gain, so I can get PBS on 16 which has Create, one of my favorites.



You can suspend a twin lead folded dipole for channel 3 in your attic to see how it works.



Channel 3, 60 to 66 MHZ, center frequency 63 MHz

5540/63 = 87.9 inches length for a folded dipole antenna
Attached Images
File Type: jpg SonyDiagScrGE34792.jpg (189.4 KB, 73 views)
File Type: jpg Folded Dipole.jpg (59.4 KB, 64 views)
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Last edited by rabbit73; 11-Feb-2017 at 4:23 PM.
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Old 11-Feb-2017, 9:23 PM   #10
rabbit73
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To convert the dipole antenna into a 3 element beam for more gain, add a reflector and a director:

Wire Reflector, 92.3 inches,

Wire Director, 83.5 inches,

dipole to reflector spacing is 37.49 inches

dipole to director spacing is 28.12 inches

Attached Images
File Type: jpg Channel 3 Yagi.jpg (112.8 KB, 57 views)
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