Near Sparta, TN: Advice? - Canadian TV, Computing and Home Theatre Forums

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post #1 of 41 (permalink) Old 2013-07-18, 06:45 PM Thread Starter
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Question Near Sparta, TN: Advice?

I'm new to the forum, have read a lot of what is on here lots of well informed friendly folks, I am from TN in the USA zip 38583 and all my signals are edge 2 or worse. Before I went to Sat I Had a 20ft mast antenna which brought in abc,nbc,cbs from Nashville and the same with weaker signal from Chatt. no uhf. Retired now. can't see paying Sat anymore. Building a 4bay bowtie.
What lenth whiskers would you recomend ? Will be using 20ga steel guy wire for whiskers
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post #2 of 41 (permalink) Old 2013-07-18, 08:24 PM
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soroco:

Welcome to the forum. The tvfool report for your zip looks like this, but a report using your exact address or coordinates in Sparta would be more accurate:
http://www.tvfool.com/?option=com_wr...46ae3bdcfc2154

Your report doesn't look very promising. The whiskers for your 4-bay antenna should be about 10 inches long on each side considering that many of your UHF channels are at the low end of the UHF band. This antenna is not suitable for your CH3 signal if it is even on the air. The antenna design depends on the REAL channel number.

http://www.rabbitears.info/search.ph...pe=dBm&height=

You will need a preamp.

If you can not measure it, you can not improve it.
Lord Kelvin, 1883
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post #3 of 41 (permalink) Old 2013-07-18, 10:35 PM Thread Starter
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Rabbit73 I think your right, I packed away a preamp 20 years ago. TVFool shows all but one of my strongest stations out of Nashville I will need 10 db gain Is the bowtie the best way to go? I was thinking 9 1\2 or 12inch on the whiskers I would like to try to build it tomorrow and shut off the Sat Maybe build it 12 and if it does not perform shorten them?
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post #4 of 41 (permalink) Old 2013-07-18, 11:45 PM
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There are two versions of mclapp's M4 4-Bay Bowtie Antennas analyzed here:
http://imageevent.com/holl_ands/multibay/4bayrefl
The one with 10-inch whiskers is slightly better for the lower UHF channels, but note that they have somewhat different Hi-VHF (Ch7-13) performance. Also note that the Bowtie-to-Bowtie separation is MATCHED to the Whisker Length....and is DIFFERENT for the two antenna designs....so it isn't as simply as trimming the Whisker Length.

More info found on mclapp's website:
http://m4antenna.eastmasonvilleweather.com/index.html

HOWEVER, as rabbit73 states, we need to see the TVFool report for your exact location.
If it's similar to the report for the zipcode (Post Office) location, for any chance of pushing somewhat into the negative NM region to maybe receive The CW on Ch20, you're going to need a High Gain UHF Antenna....and a good high gain, low noise Preamp. Of course, if you're in a better location reception could get easier.

Unfortunately, networks have moved away from long distance propagation on Ch2-6...and Digital signals are much more susceptible to Man-Made Interference that is quite high in that band. So you can't judge reception against old Analog station reception experience.

A-D 91XG is a good commercial choice for UHF, but Ch20 Gain is only about 15 dBi. If you are looking for a DIY project, consider mclapp's VM8 a Vertical 8-Bay Bowtie (two stacked M4's, see his website). But even these antennas might come up short on Gain, depending on your location, so you MIGHT need one of the Very High Gain Quasi-Parabolic "KISS" antenna designs:
http://imageevent.com/holl_ands/quasiparabolic
http://ghz24.freeshell.org/antenna/m...dels/parabolas
Additional, bigger Quasi-Parabolic designs can be found by searching forum for "KISS" and "Parabolic"

I don't want to discuss Ch3 reception until I see your exact location TVFool Report. I couldn't locate any info re what sort of programs are broadcast on that station....are you sure you NEED to receive Ch3?
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post #5 of 41 (permalink) Old 2013-07-19, 11:03 AM Thread Starter
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Channel 3 is from Chattanooga. Do not ever remember using it. TVFool report for address is same as zip. Will build several diff antenna but would like first to be most likely to work (retired empty workshop all materials (except balun) on hand)
Heading for barn to start making parts to assemble
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post #6 of 41 (permalink) Old 2013-07-19, 12:53 PM
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Per rabbitears website, WWWB city of record is Clearrange in the Knoxville DMA:
http://www.rabbitears.info/market.ph...n=wwwb#station

BTW: Although I've never been there (yet), I'm fairly familiar with your area via GoogleEarth. My Father's lineage came to the area just south of Liberty, TN in a large Wagon Train from Patrick/Henry CO, VA in 1809. Some of their extended family are buried at Liberty's Salem Baptist Church....and some moved on to populate Arkansas, Oklahoma and Colorado.

Since TVFool (and other propagation prediction programs) do NOT adequately account for the much higher Man-Made Impulse Noise levels in Lo-VHF Band, I don't think fully extended Rabbit-Ears are going to be adequate (esp. if used indoors) and the same can be said for a simple DIY 89-inch Total Length Stick Dipole (or Twin-Lead). You're probably going to need more than a mere 2 dBi Gain Antenna:
http://imageevent.com/holl_ands/dipoles/vhfstickdipoles

You might want to consider Antennacraft Y5-2-6 Ch2-6 Antenna with 4.5 dBi Gain:
http://imageevent.com/holl_ands/yagis/ch26acy5265elyagi
http://www.antennacraft.com/pdfs/Y5-2-6.pdf
or Winegard YA-6260 with 4 dBi Gain:
http://www.winegard.com/kbase/upload/Ya-6260.pdf

The simplest DIY antenna would be a Lo-VHF Hourglass (NO Reflector) with 3.5 dBi Gain on Ch3:
http://imageevent.com/holl_ands/loop...mhourglassloop
But without a Reflector, it isn't much of an improvement....I'll upload a version with multiple Reflector Rods "soonish" that should provide more than 9 dBi Gain, as seen in the Hi-VHF version:
http://imageevent.com/holl_ands/loop...fhourglassloop
A Screen Grid of equal size would also work, such as 4"x4" (or 4"x8" or even bigger) Fencing material:
http://imageevent.com/holl_ands/loops

Here are some Gray-Hoverman GN2, GN4 & GN8 designs with about 4, 4.5 & 6.5 dBi Gain on Ch3:
http://clients.teksavvy.com/~nickm/gh_n_vV.html
http://imageevent.com/holl_ands/gray...vhfsbghwnarods
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post #7 of 41 (permalink) Old 2013-07-19, 11:56 PM
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Quote:
Will be using 20ga steel guy wire for whiskers
??? That's awfully thin guy wire, are you sure of the gauge ?

That is about the poorest TVFool report Ive seen, a PBS station on channel 22 and a low power, probably crappy channel 3 is about all that can realistically be expected. My condolences.


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PS: In my 4-yo Desktop, I rebuilt OS into SDD, replaced ALL cooling fans (including a HUGE Heatsink/Fan...NOT H2O) and replaced AMD Phenom II X3 2.8 GHz (Total=8.4 GHz) with an X6 3.2 GHz (Total=19.2 GHz). I intend to Overclock to about 3.8 GHz
That's certainly gonna make it a LOT zippier, heh.

My builds/plans (not the latest models) are located here.
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post #8 of 41 (permalink) Old 2013-07-20, 12:42 AM
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Ch3 Hourglass-Loop with 5 Reflector Rods:

I just uploaded analysis results for the above Ch3 Antenna: Raw Gain in excess of 10 dBi, F/B & F/R Ratio Minimum = 12.8 dB and SWR Under 2.7:
http://imageevent.com/holl_ands/loop...ssloopreflrods

This Optimized version turned out to be an unusually TALL Antenna (19.6-ft H x 8.33-ft W x 3.4-ft D). I'll add one with just 3 Reflector Rods and try to squash it down a bit, although with somewhat reduced performance.





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post #9 of 41 (permalink) Old 2013-07-20, 12:45 AM
 
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again on the missing balun - single channel baluns can be made from coaxial cable:
http://n-lemma.com/calcs/dipole/balun.htm
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post #10 of 41 (permalink) Old 2013-07-20, 01:02 AM
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Whiskers should be AT LEAST AWG12, otherwise SWR can be degraded. AWG10 is stiff enough to resist inadvertent jarring. But for outdoor use with strong wind and ice loading, you should use even bigger diameter. FYI: mclapp's M4 4-Bay's posted on his and my websites are presumed to use AWG8 for the Whiskers and AWG12 for the Feedlines:
http://imageevent.com/holl_ands/multibay/4bayrefl

K6STI modeled the Half-Wave 4:1 Coax Balun and found losses were quite low across entire UHF Band:
http://www.digitalhome.ca/forum/showthread.php?p=868122
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post #11 of 41 (permalink) Old 2013-07-20, 01:06 AM Thread Starter
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Sorry 20 was a typo hit 2 should have hit one 10ga poor proof reading here. prepared all parts today will assemble Tuesday no balun in Spencer or Sparta. will be in Cookeville Monday pick a couple up then. I live on the Upper Cumberland Platau moved here fourty years ago from Colo. Have a 3ft X 8ft peice of 1inch mesh poultry wire I plan to mount as a reflector do you thik it will help? Neighbor about a mile away is using the coathanger from Utube and is recieveing ABC CBS NBC FOX PBS from Nashville 22 comes and goes. so I have hope.
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post #12 of 41 (permalink) Old 2013-07-20, 07:13 PM
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Quote:
should have hit one 10ga
Much better.
Quote:
Have a 3ft X 8ft peice of 1inch mesh poultry wire I plan to mount as a reflector do you thik it will help?
Yes, if you make the twists horizontal, it should give you more gain, perhaps as much gain as phasing two 4-bay antennas together. The spacing between the reflector and the elements should be about 4.75 inches if you are using 10 inch elements to favor the low end of the UHF band.
http://en.wikipedia.org/wiki/Chicken_wire
http://www.the-chicken-chick.com/201...s-chicken.html

I prefer 1 x 2 fencing, with the 1" vertical spacing for the horizontal wires.

If the elements are 10 inches, then make the vertical spacing between the inner and outer bays also 10 inches. The spacing between the two inner bays can be the same or more, say 12 inches, for a little more gain.

The connection between the inner ends of the whiskers and the vertical phasing lines should be well insulated from the rest of the structure, perhaps on plastic, because that is a high impedance point sensitive to losses. Screws that hold the whiskers and the vertical phasing lines in contact should not be fastened directly to wood.

Please let us know how it works out.

If you can not measure it, you can not improve it.
Lord Kelvin, 1883
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post #13 of 41 (permalink) Old 2013-07-20, 08:46 PM
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Ch2+Ch3 Hourglass-Loop + ReflRods - OPT:

Uploaded 4nec2 results for Ch2 and Ch3 Hourglass-Loops with Multiple Reflector Rods after Optimization using nikiml's Python Scripts. The shortest (Ch3, 3RR) is still 12-feet tall x 8.1-feet wide:
http://imageevent.com/holl_ands/loop...ssloopreflrods
BTW: I started another Optimization run...this time with an 8-foot Height Constraint....stay tuned.

a) Ch2 Hourglass-Loop with 3 Reflector Rods.
On Ch2, Raw Gain = 9.7 to 9.0 dBi, F/B & F/R Ratio Minimum = 11.8 dB and SWR Under 2.7.
Total Hourglass Height=150.0-in, Width=91.25-in & Mid Gap=1.0-in.
Reflector Rod Lengths=108.5-in with Rod-Rod Spacings=70.0-in and RR-Bowtie Separation=42.25-in.

b) Ch3 Hourglass-Loop with 3 Reflector Rods.
Ch3 Hourglass-Loop + 3ReflRods - OPT
On Ch3, Raw Gain = 9.9 to 9.2 dBi, F/B & F/R Ratio Minimum = 11.8 dB and SWR Under 2.8.
Total Hourglass Height=143.5-in, Width=82.0-in & Mid Gap=1.0-in.
Reflector Rod Lengths=97.25-in with Rod-Rod Spacings=69.25-in and RR-Bowtie Separation=38.25-in.

c) Ch3 Hourglass-Loop with 5 Reflector Rods is VERY TALL and not much improvement vs 3RR.
On Ch3, Raw Gain = 10.6 to 10.0 dBi, F/B & F/R Ratio Minimum = 12.8 dB and SWR Under 2.7.
Total Hourglass Height=152.5-in, Width=80.25-in & Mid Gap=1.0-in.
Reflector Rod Lengths=98.75-in with Rod-Rod Spacings=69.25-in and RR-Bowtie Separation=40.5-in.

Ch3 Hourglass-Loop with 3 Reflector Rods:


NOTE THAT CHART BEGINS ON 57 MHZ, VICE USUAL 54 MHZ:


NOTE THAT CHART BEGINS ON 57 MHZ, VICE USUAL 54 MHZ:
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post #14 of 41 (permalink) Old 2013-07-21, 02:45 AM
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Ch3 Hourglass-Loop + 3RR - SHORT OPT:

Uploaded 4nec2 results for Ch3 Hourglass-Loops with 3 Reflector Rods after Optimization using nikiml's Python Scripts for "SHORT" version, constrained to Max Height = 8-feet. It was found to be 8.375-feet Wide and 2.87-feet Deep. Hopefully the reduced height is easier to mount on the Roof or against a Wall or in an Attic:
http://imageevent.com/holl_ands/loop...ssloopreflrods
It loses about 1 dB of Raw Gain compared to the taller version, but provides noticeable F/B & F/R Ratio improvement and better SWR.

d) Ch3 Hourglass-Loop with 3 Reflector Rods, Max Height = 8-feet ("SHORT").
On Ch3, Raw Gain = 8.7 to 8.1 dBi, F/B & F/R Ratio Minimum = 14.5 dB and SWR (300-ohms) Under 2.0.





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post #15 of 41 (permalink) Old 2013-07-21, 05:44 PM
 
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Gentlemen,

You shouldn't bother about channel 3, as per TV Fool's "Pending*
applications", WWWB-LD has or will be moving to channel 50.

.
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