Charlotte, NC - OTA - Page 291 - AVS Forum
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post #8701 of 8715 Old Today, 01:23 AM
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Originally Posted by ejb1980 View Post
.

I realize that that was a long post about out of market stations. But it goes to show that sometimes the location of a sweet spot is in a far-from-logical place.
My problem was caused by a mathematics error that I made in the derived impedance that I used to build the antenna. This is why rebuilt the driven element by changing the length of the copper loop and electrically floating it. The mark II antena works fine in either location. The engineer in me doesn't like to rely on assumptions which is why I kept at it until I discovered what was causing my problem. i.e. Theory did not match tested results.

IMO strange unexplainable things & sweet spots are almost always caused by something real, but unknown. With antenna installs, I'd say that 99x out of 100 it's either due to the wrong antenna, cabling, and unknowns related to indoor/attic installs. The first two are easy to deal with. The latter....????

This is why I don't recommend attic installs and nobody else should who claims to know something about it. Sure, it can be made to work but for anyone wanting to just watch TV without a research project should expect on going issues if they go there. A few will get lucky but gambling is something I'd rather do at a craps table. Spending a day in a hot attic, pulling cable, etc. can be quite a let down when the results don't match the expectations.

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post #8702 of 8715 Old Today, 04:01 AM
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Originally Posted by hamstang View Post
Today I noticed what I think is a radar dome on a tower near the Oakdale section of NW Charlotte. The round dome is too small to be a water tower I think. Would that be related to weather radar and any of the Charlotte TV News Departments?
The Charlotte Terminal Doppler Weather Radar, installed by the FAA, is in the area, off Miranda Rd. near Beatties Ford Rd.

http://www.erh.noaa.gov/gsp/tdwr/info/specs.html
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post #8703 of 8715 Old Today, 04:31 AM
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Originally Posted by blackcat6 View Post
My problem was caused by a mathematics error that I made in the derived impedance that I used to build the antenna. .

You didn't double check the math before construction? Isn't that a basic engineering tenet? That could have been costly had it made it to the production line....

Bob

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post #8704 of 8715 Old Today, 04:45 AM
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Originally Posted by bdfox18doe View Post
You didn't double check the math before construction? Isn't that a basic engineering tenet? That could have been costly had it made it to the production line....
I have a copy of Antenna Theory and Design, by Stutzman and Thiele. The copy I have has a floppy disk in the back cover for formulas. That and a TI-83 Calculator were mandatory for my old classes.

Bob helped me with my MPEG classes because there are things implied that are not explained in classes that well.

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post #8705 of 8715 Old Today, 05:43 AM
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Originally Posted by blackcap93 View Post
The Charlotte Terminal Doppler Weather Radar, installed by the FAA, is in the area, off Miranda Rd. near Beatties Ford Rd.

http://www.erh.noaa.gov/gsp/tdwr/info/specs.html
Thanks, blackcap93. Excellent info.
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post #8706 of 8715 Old Today, 06:29 AM
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Originally Posted by bdfox18doe View Post
You didn't double check the math before construction? Isn't that a basic engineering tenet? That could have been costly had it made it to the production line....
Well.... happens to the best of us. Was using mm (metric) and mils (US customary) at the same time. Got me sums mixed up. Why? Because I like to figure it in metric but I like to measure it in American.

NASA crashed the $330M Mars Climate Orbiter into Mars because they mixed up metric measurements with US measurements. Took the rocket scientists longer to figure it out than me.
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post #8707 of 8715 Old Today, 06:34 AM
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Yea, I hear ya. There are no original mistakes. Even the best of us sometime forget to measure twice and cut once, as my grandpa would say.

Bob

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post #8708 of 8715 Old Today, 06:45 AM
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Originally Posted by ybsane View Post
.....That and a TI-83 Calculator were mandatory for my old classes.

....
Fancy calculator.. I lifted a lot of boxes into the back of trucks at UPS to afford one of these dinosaurs. (sort of wish I still had it)

http://en.wikipedia.org/wiki/TI-59_/_TI-58

Though there are is always this. There are still some around that insist that only real men use them.

Your Granddaddy's calc
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post #8709 of 8715 Old Today, 07:11 AM
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Originally Posted by blackcat6 View Post
Fancy calculator.. I lifted a lot of boxes into the back of trucks at UPS to afford one of these dinosaurs. (sort of wish I still had it)

http://en.wikipedia.org/wiki/TI-59_/_TI-58

Though there are is always this. There are still some around that insist that only real men use them.

Your Granddaddy's calc
That is my Dad's Calculator and he still has it, He worked for GE/Westinghouse as an Engineer and his favorite item is a tube checker he got when our old Drug Store closed down.

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post #8710 of 8715 Old Today, 08:30 AM
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..... He worked for GE/Westinghouse as an Engineer and his favorite item is a tube checker he got when our old Drug Store closed down.
I don't remember what happened to it, except that TI calculators had a reputation at that time for developing key bounce issues.

I had a professor once who stuck a vacuum tube circuit on a final exam. He got a lot of complaints about that since transistors had replaced them by decades. I never had much of an an appreciation for them until a few years ago when I saw someone make one in a back yard and then demonstrate what could be done with it.

I would love to have a box of large nixies from the 70s.

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post #8711 of 8715 Old Today, 10:15 AM
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Originally Posted by bdfox18doe View Post
You didn't double check the math before construction? Isn't that a basic engineering tenet? That could have been costly had it made it to the production line....
Most people don't realize there are mathematics and physics involved. They just want to throw up some random antenna in the attic and magically expect it to work. Sometimes they will luck out, but not always. I realize there is engineering science involved, but I don't claim to understand it. I just have a little bit of consumer experience with various antennas over the years.
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post #8712 of 8715 Old Today, 10:37 AM
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Most people don't even want to go to that trouble. I installed an attic antenna for my retired IBM engineer father-in law who did not want it on the roof. Perfect reception on all locals all the time..because he did not want to pay DirecTv. He finally decided it was too much trouble to be switching between Tv and DirecTv..(truth be known probably more my mother in-law than he)..and went back to paying for the locals based soley on operational convenience.

Bob

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post #8713 of 8715 Old Today, 12:36 PM
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Hmm. I was under the impression that an antenna could be hooked directly to a DTV receiver and it would integrate the channels into its EPG. This works well on Dish. (well except for missing guide data on some subchannels)
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post #8714 of 8715 Old Today, 12:45 PM
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Originally Posted by blackcat6 View Post
Hmm. I was under the impression that an antenna could be hooked directly to a DTV receiver and it would integrate the channels into its EPG. This works well on Dish. (well except for missing guide data on some subchannels)
I think you would need a ADD On Box to receive the OTA with Directv AM21 box

see
https://support.directv.com/app/answ...r-tuner-manual
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post #8715 of 8715 Old Today, 12:56 PM
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Yes, I have one on one of my 4 receivers. Tho if I am correct not all models support it.

Bob

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