TV antenna any good?
- Thread starter ic746
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Don_Burke
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Sometimes you get FM broadcast overload off a TV antenna, but for the most part, they work fairly well. I would not call it "good."
ridgescan
Member
Since Ive learned from the smart guys here that TV waves run horizontally, and radio waves run vertically-maybe you should turn that TV antenna sideways then mount it in the most desired direction, it is, after all, directional
Since Ive learned from the smart guys here that TV waves run horizontally, and radio waves run vertically-maybe you should turn that TV antenna sideways then mount it in the most desired direction, it is, after all, directional
but the elements are tuned for the TV frequencies not the scanner freqs so it would work properly. directional antennas only work well for the designed freqs. Of course if you have lots of experience you can shorten or lengthen the elements to match the scanner bands but that's a difficult task. I've modified a TV antenna but it was a chore. plus if you have the money just get the Grove Scanner Beam, it looks like a tv antenna but for the scanner bands.
Eric Burris
K4DHR
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Why wouldn't it? Quite a few of the soon to be extinct higher TV channels are in the low 800 MHz range. It is likely that most of the TV antenna designs probably date back to when TV extended into the mid 800 MHz range.
I say this because I used the TV antenna on the roof of my parent's house for my scanner and it pulled in the neighboring county's trunk system quite well.
PHOENIX_SCANNER
Member
Ok, for you antenna gurus, how about turning it 90 degrees by drilling new holes and mounting it as a vertical? With the elements being so close to a (metal) mast, would there be issues?
Just wondering.
My personal experience is that almost ANYTHING above the roofline will work better than a duck antenna on a portable. Even a piece hanger wire would work better. The overall difference between my PSR-600 with a cheapo 20-176 and my PSR-500 with ANY duck antenna is like night and day, and when I am near my base scanner the portable stays off. I would say ANY rooftop antenna will generally be better overall, than using the stock antenna. If all you can get is a tv antenna, use it. My thoughts.
Just wondering.
My personal experience is that almost ANYTHING above the roofline will work better than a duck antenna on a portable. Even a piece hanger wire would work better. The overall difference between my PSR-600 with a cheapo 20-176 and my PSR-500 with ANY duck antenna is like night and day, and when I am near my base scanner the portable stays off. I would say ANY rooftop antenna will generally be better overall, than using the stock antenna. If all you can get is a tv antenna, use it. My thoughts.
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ridgescan
Member
So true, Eric
but I bet it'll still give him decent reception in the direction it's pointed especially in the bands it was designed for.
ridgescan
Member
Thats what I said above^^
IMO it should perform sweetly! I hope the OP tries it then inform us
ic746
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Thanks fellows I appreciate your help on this. At the moment I have a discone antenna up 40 feet and it seems to be doing great. I was just wondering that since I have these new in the box tv antennas how they would do. I am going to mount one vertically and use LMR-400 coax on it. When I get it up I will inform everyone how it does.
Calvin
Calvin
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jon_k
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The antenna may be designed for frequencies close to what you monitor but this isn't the only thing you should consider.
The antenna and coax are made for 75 ohms. Scanners and radio gear expect 50 ohm. For transmitting this is a big deal. An impedance mismatch will result in reflected power to your transmitter and destroy the transmitter. I can only wager it has importance with receiving as well. Improper impedance will result in an attenuated signal.
This will be impossible to correct without a balun transformer which you may wish to invest in.
The antenna and coax are made for 75 ohms. Scanners and radio gear expect 50 ohm. For transmitting this is a big deal. An impedance mismatch will result in reflected power to your transmitter and destroy the transmitter. I can only wager it has importance with receiving as well. Improper impedance will result in an attenuated signal.
This will be impossible to correct without a balun transformer which you may wish to invest in.
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Channels 69 is on the edge of 800mhz, Most TV antennas are built for VHF and UHF reception. Granted some may work up higher, I never said they wouldnt just wouldnt work well. Any piece of metal will receive a signal, how well is the issue.
Since Ive learned from the smart guys here that TV waves run horizontally, and radio waves run vertically-maybe you should turn that TV antenna sideways then mount it in the most desired direction, it is, after all, directional
Well,"TV and radio waves" will run what every way you transmit them. You will actually find that many TV stations actually transmit circular polarized signals. traditionally most broadcast you would receive on your scanner are vertical.
Don_Burke
Member
I doubt many UHF or VHF/UHF antennas have been redesigned since UHF TV went up to channel 83 at 960 MHz.
Don_Burke
Member
For this application the loss from an impedance mismatch will be nearly undetectable.
K4DHR
Member
That's what I was driving at.
Actually if you look at whats being sold for "tv" antennas they have been re-designed. Gone are the BIG log periodic antenna most associated with TV's. IN there place is are smaller "HDTV" antennas that are all in one amplified. Yes you can still find the anodized aluminum "deep" signal antennas and I have even seen a resurgance in the in the curtin antenna's but Many of the antennas being sold are these smaller, amplfied alien death ray looking yagi's.
PHOENIX_SCANNER
Member
Home depot still sells the old school tv antennas. I bought one a few years back.
Since everything around here is now digital it got taken down and now I have a four bay "HDTV" antenna up. Maybe I should play with the old tv antenna and see what it does.
Since everything around here is now digital it got taken down and now I have a four bay "HDTV" antenna up. Maybe I should play with the old tv antenna and see what it does.
If a 50 ohm to 75 ohm mismatch is going to keep you up at night. A 1/12 wave matching device can be build with a piece of 50 ohm coax and 75 ohm coax soldered together. Each piece of coax has to be cut to the 1/12 wave formula. This isn't a broadband solution though and is used for single frequency matching.
ic746
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Thanks again for all your answers, if I use the LMR-400 coax for this tv antenna mounted vertically, does anyone think it will work? I am about to go to a hamfest in August and if this LMR-400 cable isn't going to be the best solution for this I can find some good 75ohm cable there. And again all answers will be greatly appreciated.
Calvin
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