I know the JC forum group is great with NEW technology, but what about long established technology, like TV antennas?
For years, I’ve gotten excellent reception from our roof antenna, aimed toward the Empire State Building (following 9-11-01, when reception was really bad because most stations had their transmitters on the WTC).
Now they all have their transmitters on the Empire State Building.
In the last 2 weeks, Channel 7, WABC, has been coming in poor, with shadows and flipping and stuff. I phoned the station, and they insist their transmitter is STILL on top of the Empire State Building.
All the connections are good. I climbed up on the roof and swiveled the antenna, with no results.
What’s the problem? Why can’t I get good reception on Channel 7? Why would this suddenly change?
I vaguely remember us having one when I was little… when it didn’t work right my dad would have me move it around untill the picture came in, then I had to stand there and hold it untill the show was over. Maybe you could try that.
In the quest to solve Billy’s problems one should never hold back. There are no stupid ideas only unexpressed ones. And for all Billy brings to this forum it is our obligation, nay our duty, to give him our all.
Back in the day, I made a TV antenna tuned to channel 12 because they had lots of movies but were in Bellingham, about 80 miles away. I used some 300 ohm balanced transmission line (RadioShack) cut to a half-wave resonant length (folded dipole) with the ends shorted and the feeder attached in the middle. It’s a TEE shaped arrangement like you would have for your FM receiver. The folded dipole was mounted on a piece of wood (probably some quarter round molding) and the feeder ran down to the boob tube. That piece of wood was mounted perpendicular to another piece of wood which had 6 heavy copper wire (AWG 10) directors attached in front of the dipole and one reflector in back. The directors are cut to 0.9, 0.8, 0.7, 0.6, 0.5, and 0.4 half wavelengths. The reflector is cut to 1.1 half wavelengths. The directors and reflector don’t have to be electrically attached to anything. They are spaced 0.1 wavelength from each other. That piece of wood was mounted to a 1" dowel rod which I used as my mast. I put the whole thing in the attic and pointed it at Bellingham.
The whole thing is easy to build if you’re not an ignorant, urban cracker. Just Google “folded dipole antenna” and you’re off. I may have lied to you about the spacing but that’s how I remember it. That was close to 30 years ago. The length of the dipole itself will be somewhat different than a half wavelength because the 300 ohm transmission line is in a dielectric medium that slows down the RF propagation. All of that info should be in gobs of articles on the web. If not, PM me and I’ll give you the lengths and spacing.
Do this. Don’t be a sissy, it’s fun. More fun than a Coker ride at Grant’s tomb. Well…not quite that fun.
Come to think of it, the standard roof top TV antennae are probably tuned to something in the midband. This may already be channel 7 but I don’t know. The VHF band is broken up into about three ranges.
Thanks but it’s not the weather, it’s been too consistent over too long, with too many weather changes. It may be some roof raising or roof construction is starting to block my view, but I wonder why it’s only affecting Channel 7.
Greg, thanks for your advice, which I’ll assemble along with the web site info, and try to put together something.
I wonder if I can run this into my already standing antenna, or even extend upwards from it and merge it into the already ex9isting antenna.
Yes you can do this but it requires some clever tinkering with resonant stubs to isolate the two antennae. Also, they would have to be spaced far enough apart so that director and reflector elements from one antenna unit don’t excite the other antenna. It would be simpler to build one tuned for the station of interest and attach it at the existing antenna’s feeder while disconnecting (and moving) the existing antenna. The tuned antenna will not appreciably degrade reception of other channels in the VHF band (2-13). Your existing antenna may have a UHF loop antenna incorporated. If that is the case I think that the two are so poorly impedance mismatched that they are essentially isolated. I don’t know how to incorporate a UHF antenna into this one.
Stay cheap and simple when you find out what the numbers are and put this together. If it doesn’t help you haven’t wasted a lot of time and money. Mine worked really well.
Is this analog TV reception or have you made the jump to digital yet?
Over the air digital reception works well. I just set up an indoor rabbit ears style digital TV antennae for the parents (they just got a new fangled HD TV). Works well. The analog stations all have snow but the digital ones are strong and clear. They’re about 15 miles from the broadcast towers and don’t have tall buildings or trees in the way.
Analog is going away very soon. Doesn’t make sense to spend money on analog reception. Might as well take the jump and get a digital tuner and digital antennae now.