How to build a UHF antenna... - Page 163 - AVS Forum | Home Theater Discussions And Reviews
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post #4861 of 4899 Old 01-05-2016, 08:09 PM
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Hi all. I have perused much of this thread, admittedly not all of it.
I have relied very heavily "DIY TV Antennas" for a 4 bay. Sorry can't post the web link yet. Need 4 more post to do that. Works pretty good for being almost 60 miles from the transmitting antennas. Made some mistakes during the build. One intentional because I used as much of whatever I had on hand, and did not have to purchase. The 2 mistakes being I used chicken wire as a reflector because I had it. And then I mounted it to far back from the elements. I will fix those later when I make the next upgrades.

The test article was 4 pair of bow ties fastened to a 2x4 and leaned against the roof. Just 4 bowties, no reflector. Was really shocked at how well it worked. Now it is on a 20 foot mast (not a speck of wood in the build). I also made a single penny loop (with no reflector) atop the bowtie array for real channels 9 & 10, (23" loop). Tied the whole affair together with a 2 way splitter. With out a booster I get decent reception. Most channels show mid 80% range and a swr of around 23. A booster helps. Only when the weather turns poor does reception drop off to much. The uhf channels that I care about are 25, 35, 40 (these 3 the most) and 58, 64. All the rest are junk that you could not pay me to watch. Well how much pay are we talking about?

I put the whole thing up before I remembered pictures. Oh well. I used ¼” aluminum rod for the bowties. Much to spendy and hard to bend. 3 snaped.

I have sourced some 1/8” aluminum rod from Metal Depot at maybe a ¼ of what I paid for the ¼” rod. Also thinking about some stranded steel cable. Much cheaper yet.

Now my question. Where and how do I join extra arrays. I am planning on going up to 16 pairs of bow tie (at minimum 8). I want to do 8 on one section and 8 on the other. Shorter bow ties on one section that I can turn independently for the 2 high UHF channels (58, 64).

I am also going to replace the penny loop with a pair of folded dipole yagi's. If I use stranded steel wire I will have to support the lengths somehow.

Will continue to bring the two bands together with a splitter.

Thanks for any put.

Ken

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post #4862 of 4899 Old 01-06-2016, 08:19 AM
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The 2 mistakes being I used chicken wire as a reflector because I had it.
Chicken wire isn't quite as good as 1 x 2 wire fence, but you can use it if the twists are horizontal. The reflector should be 4-1/2 inches behind the elements.
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Tied the whole affair together with a 2 way splitter.
A UHF and a VHF antenna should be combined with a UVSJ, not a splitter in reverse as a combiner.

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Where and how do I join extra arrays.
With a splitter in revere as a combiner, with equal length coax lines, if it is two identical 4-bay UHF antennas.



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post #4863 of 4899 Old 01-06-2016, 05:18 PM
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Hi rabbit73 and thanks for the reply.

Just had a duh moment and realized that what I called chicken wire was really hardware cloth. My bad, just now realized it after all this time, I have been calling it the wrong thing. 1/4" square wire.

Thanks for the tip on the UVSJ. Did not realize that.

Oh and one more question. Should the reflector(s) be grounded or insulated on plastic stand offs like the active elements?

Thanks

Ken

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post #4864 of 4899 Old 01-06-2016, 05:23 PM
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Hi rabbit73 and thanks for the reply.

Just had a duh moment and realized that what I called chicken wire was really hardware cloth. My bad, just now realized it after all this time, I have been calling it the wrong thing. 1/4" square wire.

Thanks for the tip on the UVSJ. Did not realize that.

Oh and one more question. Should the reflector(s) be grounded or insulated on plastic stand offs like the active elements?

Thanks

Ken

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post #4865 of 4899 Old 01-06-2016, 05:28 PM
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Sorry about the double post. New mouse with side buttons that my arthritic thumb knuckle keeps hitting. I lost the above post twice because of it. Can't disable it in software. I may disable it in HAMMER WARE.

Ken

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post #4866 of 4899 Old 01-12-2016, 10:28 AM
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Hi all,

Been reading all the DTV antenna threads with interest. I live in the Boston area, and recently became a cablecutter. I decided to homebrew a simple UHF antenna from scratch. (Since Boston is practically an all-UHF market, I concentrated on UHF reception rather than try to get the one or two VHF channels)

It uses 9" whiskers made from copper wire that is stretched between some small bolts on a piece of black foamcore board. The vertical separation of the whiskers is about 3", and the feedpoint spacing is approximately 1".

I made some intial tests with and without the 300 ohm balun at the feedpoint. There was no discernable difference in performance of quality, so I ditched the balun, since the feedpoint of a single bow tie is close to 75 ohms anyway.

The antenna is mounted on the highest indoor point on the second floor. This is fed to a TV downstairs by 35 feet of (93 ohm) RG62A/U. There are no apparent issues with the 93 ohm impedance of this cable, and since the feedpoint of the bow tie (nominally 75 ohms) varies according to frequency anyway, I can see no sense in worrying about an 18 ohm difference.

You can see I added some 5" whisker "extensions" using alligator clips. After some experimentation, the added length has stabilized any channels that were iffy. For whatever reason, this antenna beats a 4-bay version in terms of flexibility and performance, I "lock" about 30 channels with various sub channels - all rock solid. Not bad for some foam core and wire.
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post #4867 of 4899 Old 01-12-2016, 05:54 PM
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I've added a photo of the 4-bay version I made using the Mclapp-4 dimensions. Interestingly, there was no significant improvement over my "quick and dirty" single bow tie.
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post #4868 of 4899 Old 01-14-2016, 12:33 PM
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Quote:
Originally Posted by Kenp51 View Post
Hi rabbit73 and thanks for the reply.

Just had a duh moment and realized that what I called chicken wire was really hardware cloth. My bad, just now realized it after all this time, I have been calling it the wrong thing. 1/4" square wire.

Thanks for the tip on the UVSJ. Did not realize that.

Oh and one more question. Should the reflector(s) be grounded or insulated on plastic stand offs like the active elements?

Thanks
From a PERFORMANCE viewpoint, it "shouldn't" make any difference whether the Reflector is grounded or isolated.

From a LIGHTNING PROTECTION point of view, it is better to ensure that there is AWG10 or larger wire from the Screen Reflector to the (presumably) METAL Mast....this will drain off any Static Electricity Charges that build up from wind passing across it (the higher the wind, the larger the Voltage)....the same way that Static Electricity can be built up by shuffling across a carpet. If the Antenna is the SAME Voltage level as surrounding Rooftops, it's less of a target than if it has a significantly DIFFERENT Voltage level which can ATTRACT Lightning Bolts.

And obviously, you can't run a "ground" wire to the ACTIVE Antenna Elements (e.g. Bowties or Folded Dipole in a Yagi).....but an OUTDOOR Balun (I've verified Channel-Master, Philips & RCA) SHOULD provide a DC path from the 300-ohm Twin-Leads to the outer Coax Shield to dissipate Static Electricity via that path to the mandatory Ground Block at the structure entry point.

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post #4869 of 4899 Old 01-15-2016, 07:47 PM
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Thanks holl_ands thanks for clearing up the reflector ground issue for me.
I picked up a ground block to attach at the pole base. I will run my coax down to it and then into the house. Right now I have one length of coax all the way from the antenna to the TV. Makes testing new parts a pain. Have to lower the whole thing.

I have made up up more bow tie >. Now assembling them. Also made up a pair of folded Dipoles for the vhf.

Be a bit before I can test.
Going to make up a angle pointer. and a spreadsheet for all of the info for the different channels so I can get accurate comparisons.

Ken

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post #4870 of 4899 Old 01-21-2016, 11:37 AM
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Another follow up question if I may?
The bow ties (4bay) I am now using are 9". I am going to add another 3 bays. Can I use a bay with shorter bowties, say 7"? That would be to get our two high channels, 58, and 64.

If so what should be the spacing of the bow ties? Tons of info for 9" and bigger, but I have struck out on finding anything for 7".

Is 7" to short for 58, and 64?

Will start assembling this bad boy after pay day. A few more things to buy.


Here are some pics of what I have so far. The vhf folded dipoles elements are ran through a fiberglass arrow shaft to support them. all the elements are tightly twisted steel wire. Gives it a much greater cross section, as well as makes it some what stiffer. Still need the arrow shaft support though.
Yeo one of the bow ties had a mismatch in element size. I caught that looking at the pics. Already fixed that. http://s1281.photobucket.com/user/ke...tml?sort=3&o=0 The mounting plates are just plastic cutting board from Wal Mart. 99 cents each and then cut into strips on the band saw. 1/32 threaded rod cut into 1' lengths for bolts and left over scraps of plastic board cut into square washers.
http://s1281.photobucket.com/user/ke...tml?sort=3&o=2 http://s1281.photobucket.com/user/ke...tml?sort=3&o=1
The original bow tie I made was much more expensive to make. I used 1/4" aluminum rod. Man is that stuff hard to bend 270 degrees or there abouts. Broke 3 rods before I figure it out. Rods were about $4 each and if no breakage yielded 2 elements. Then the fasting bolts and nuts ran me more $ yet.
I will have another 12 element pairs for less than I spent on the first 4.
The most expensive part in this added build are the arrow shafts, and square aluminum rod.

Ken

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post #4871 of 4899 Old 01-21-2016, 01:30 PM
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That would be to get our two high channels, 58, and 64.
All channels above 51 are no longer in use for TV broadcasting. Those are "virtual" channel numbers (the old analog channel number, specifically), you must look up their "real" or "RF" channel in order to determine what element size would be optimized for them. Those two Sacramento-area stations broadcast on channels 46 and 26 respectively.

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post #4872 of 4899 Old 01-21-2016, 02:00 PM
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Real Ch26 is on 545 MHz and Real Ch46 is on 665 MHz. You can't simply pick a Whisker Length and hope for the best....the overall design, including Bowtie Spacing, Feedline Separation (which increases OVERALL Width) and Separation to Reflector must be JOINTLY Optimized as a complete, interacting SYSTEM.

Your best choices would be the M4 (10x9.5) or Free-Form FF4 [4-Bay with DIFFERENT Element Lengths]....or FF6 (6-Bay) which has an extra BUMP close to Ch26 for the FLATTEST overall frequency response:
http://imageevent.com/holl_ands/multibay/4bayrefl

Or a Pair of Vertically Stacked M4 (9.5x9.0) [I haven't yet run Optimization for M4 (10x9.5)], or a pair of FF4's...or a pair of FF6's all of which have fairly FLAT frequency response:
http://imageevent.com/holl_ands/stac...allystackeduhf

You didn't explain HOW you would Combine them, but if they are pointed in the same direction, they all need to be MATCHED wrt Gain and Phase....which means identical construction....and you would need to JOINTLY RE-OPTIMIZE a mis-matched combination to minimize SWR problems and Cancellation NULLS.

BTW: To combine two DIS-SIMILAR Antennas (e.g Hi and Lo-Band UHF), you should use a Join-Tenna (or equivalent), which is a pair of Bandpass/Bandreject Filters that isolates the effect of one Antenna on the other....similar to a VHF/UHF Band Diplexer (aka Combiner/Splitter)....so it's more cost effective to use an Optimized Design from the start. You would ALSO have to construct an Antenna Optimized for Ch26, which would involve changing ALL of the Dimensions for one of the existing Antenna Designs and making them BIGGER by approx Rescale Factor = 681/545 = 1.25.




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post #4873 of 4899 Old 01-22-2016, 08:53 PM
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Dang it I pulled a silly. I made a spreadsheet of all the relevant channels to me. Their virtual and real channels., broadcast frequency, etc.
I transposed the real and virtual channel numbers for 58, 64. Thanks for pointing out the real numbers for me. Geez garbage in , garbage out.

I stumble onto a gold mine today. Found a old mostly busted up tv antenna today, intwined into a grape vine. I cut it out of there. Lots of square aluminum tube. 2 50", 2 18", and a 60" piece of 1"square tube. All the tube is in decent and usable shape. Gold mine. Would not have found it if not for chasing the neighbor's chickens back across the fence.

I will order a Pico Macom UVSJ UHF VHF Band Separator/Combiner for Antenna (UVSJ)
http://www.solidsignal.com/pview.asp?p=uvsj

Ken

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post #4874 of 4899 Old 01-29-2016, 07:58 PM
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Thanks holl_ands
That reference you posted is exactly what I am building
I have to get some flat stock aluminum to extend the 50" tube 3.5" each end to get the correct spacing for the end elements. Also have to get more cutting board as I had already cut them based on the original antenna I built. That had 1.25" phase line separation, this 1 is 3 I see after printing it out. No big deal.
To make this thing cheaper I am cutting threaded rod into studs versus pay threw the nose for bolts. I guess I need to stand my plastic mount plats off the aluminum spine at least an inch to keep the space lines from being to close to it and thus ground.

It is slow for me because I am also working on other projects (a fence that fell down. that and my disabilities really slow me down and limit my endurance.

Will report at completion and with some pics.

Ken

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post #4875 of 4899 Old 02-19-2016, 08:15 PM
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I have the FF6 (6-Bay) assembled at this time. The drwing shows the phase lines and element center point right at 3" apart. Looks like a lot but I built it as per the drawing.

When I ran the phase lines, it was naturally no issue in the center section where the lines are straight and do not cross.
But on the last 2 bow tie pairs at either end they cross. I fussed and fought with the lines (#14 copper wire) to keep the lines on each side the same length and 3" apart even as they crossed each other. I will not say I was exact, but reasonably close. But man are they ever BABOON BUTT UGLY! And I thought I might loose my mind before I got the last one done.

Now a question. What is the reason 300 ohm twin lead can not be used between bow tie pairs. Is it 300 ohm between each side of a bow tie pair?

It almost a rhetorical question I admit, since I already wired up the 6 pairs.

Ken

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post #4876 of 4899 Old 02-21-2016, 10:49 AM
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Layout Errors of 1/4-inch are nearly undetectable in the 4nec2 MODEL and in actual use, you probably couldn't detect the effect of even a 1/2-in Error..."Don't sweat the small stuff...."

I suppose you COULD design and build a 4-Bay with Twin-Lead instead of hard copper wires....buy why WOULD you????

The entire design would have to be RE-OPTIMIZED with the additional CONSTRAINT of FIXED Impedance Feedlines which MAY reduce the Gain and result in higher SWR, whereas in the FF4/FF6 designs they are VARIABLE, depending mostly on the Feedline Separation.....and NO, I'm not volunteering to do this futile exercise....

It would also be susceptible to MOISTURE increasing the LOSS in the Feedlines, whereas FF4/FF6 designs are very resistant to rain and snow....

PS: Could you post detailed PHOTOS of your FF6 to show others what it looks like???? And let us know how your Reception Performance changes....
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post #4877 of 4899 Old 02-21-2016, 03:17 PM
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Hi, been awhile since i last posted (page 69?). I decided to reread posts from beginning and have made it to page 89 with a link to the 4nec2 program at http://home.ict.nl/~arivoors/Home.htm The page is shutdown as of January 1st. post #2647 My Question is another (safe) site to download from? Thanks, Tim
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post #4878 of 4899 Old 02-22-2016, 11:29 AM
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It has been moved to a website host with higher capacity: Simply Google "4nec2 download"....
http://www.qsl.net/4nec2/
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post #4879 of 4899 Old 02-22-2016, 08:36 PM
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It took me a little more than a week to build my new antenna, A FF6 (6-Bay). I mounted it this afternoon. It is a heavy son of a gun, boy!
The results. OH HECK YEAH! WOW! What an improvement!!!
I took the old 4 bay down 2 days ago. I was getting from 30% to 77% depending on the time of day and how clear the weather was.
I only eye ball aimed the new one. Proper aiming will be done tomorrow.
The numbers. So far most channels come in at 97% Those are the UHF channels. This is the FF6 (6-Bay) with a hardware cloth reflector 4" behind the active elements. The VHF channels are coming in at 92% For those I have 2 Folded Dipoles with a hardware cloth reflector 11" behind the active elements. I cut one stud to short so just made the other to match. The reflector was supposed to be 12" behind. Oh well an inch should not make much if any difference.
The folded dipoles use a 300 ohm to 75 ohm balun. The folded dipoles are 31.25" fold to fold. And are about 8" apart. They are just for real channels 9 & 10. One of the reference sites for the folded dipole. http://www.skyscan.ca/Antennas.htm
My reference for the 6 bay bowtie was
http://imageevent.com/holl_ands/mult...aybowtienorefl
I tried to strictly follow the guidelines
All of the elements (VHF & UHF) are made from two strands of steel wire tightly spun together The wire is about 5/64" close to 14 quage wire I think. After twisted together the wire ends up about 10 /64". So it doubles and is markedly stiffer.
The 2 folded dipoles are connected by a balun each to a 3' rg6 coax into a 2 way splitter (output side) and then a 3' rg6 coax feeds into a Pico Macom UVSJ UHF VHF Band Separator/Combiner for Antenna (UVSJ)
http://www.solidsignal.com/pview.asp?p=uvsj
The UHF 6 bay also uses a balun and a 3" rg6 coax into the UVSJ.

EVERY CHANNEL I WANT IS STRONG!!!!

holl_ands thanks so much for your input. Thanks for taking the time to explain why twin lead is a no go. ,I knew there were valid reasons, but was clueless as to what they were. Thanks

I must say the 6 bay is one big sucker. WOW!

OH one more note I did not put this unit up as high as the old 4 bay and pennyloop. It sawed pretty good in a stiff wind. The mast was 2 10" sections with a roughly 6.5' mast head that the antennas where bolted to. The mast was tied to the roof at about 10.5", so basically a 10' section and the mast head above the roof anchors. And yes I reinforce the roof header with a 2x4 lag screwed in between the roof rafters.

Now to try and post the pics
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post #4880 of 4899 Old 02-22-2016, 09:22 PM
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One more pic. The folded dipoles beforemounting or attaching balun
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post #4881 of 4899 Old 02-22-2016, 09:30 PM
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The plastic for the element mounts is roughly 1/8" cutting boards from Walmart, 88 cents each cut into 2" wide strips on my band saw. I think I got 3 each cutting board. Pretty cheap.
For bolts I bought 1/4"20 all thread 3' lengths and cut into studs for the heavy bolting needs. For the lighter bolting needs I use 10 24 all thread. Much cheaper than buy bolts. And you can just cut to the length you need with a hack saw. Have to dress the ends. I cheated. Used my 1" belt sander to even the end and the rounded off a bit. Works a charm. Except for the brunning fingers thing.

It might seem 8 days is a long time to build this antenna system. But I am very limited in my physical endurance, and especially time on my feet before the pain levels become eye ball crossing for me.

I am sure some one else could build it much faster.

But man O man am I pleased with it.

Next step is to distribute the feed to another TV. We will see what the signal strength is after a splitter. I may later on invest in a amplified 4 way splitter. Although at the moment I only need 2 feeds.

Ken

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post #4882 of 4899 Old 02-23-2016, 04:17 PM
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Got the other TV hooked up. Did not see any loss of signal strength after the splitter was added.
The reran auto set up on our TV. Got several additional channels.

Would like to find more info on VHF antennas. It would be cool to get that band up to the same increase as we now see on the VHF bow ties.
I sort of think my folded dipoles are to close to together for one thing.

Ken

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post #4883 of 4899 Old 02-24-2016, 08:15 AM
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Got the other TV hooked up. Did not see any loss of signal strength after the splitter was added.
The reran auto set up on our TV. Got several additional channels.

Would like to find more info on VHF antennas. It would be cool to get that band up to the same increase as we now see on the VHF bow ties.
I sort of think my folded dipoles are to close to together for one thing.

I wish I had been paying more attention to this thread and had noticed that you were in Modesto. I'm about the same distance from Walnut Grove that you are but you have a much better location than I do. I looked at the TV Fool report for Modesto and all the Walnut Grove stations are LOS with strong to very strong signals. Reception of those stations should be very easy. If the antenna you built hadn't produced strong signals then there would have been something wrong. My portable test antennas pictured below mounted 30' off the ground would have no problem with Walnut Grove.

You should point your antenna towards Fresno. TV Fool shows you are LOS to most of the Fresno stations and you should be able to receive those. More of a challenge would be the SF stations but not impossible.

More information on building an LPDA for high VHF can be found at the link in my signature.
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post #4884 of 4899 Old 02-24-2016, 01:12 PM
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Since I couldn't find your TVFool Report, I looked at TVFool for "downtown" Modesto Zipcode to see what Lo-VHF and Hi-VHF stations might be receivable:
http://www.tvfool.com/?option=com_wr...5134012d427257

KSCO on Ch3 is strong enough that you MIGHT be receiving it already....and MIGHT receive it on an upgraded Hi-VHF Antenna. KSCO is an independent station with a heavy mix of news and talk, talk, talk:
https://en.wikipedia.org/wiki/KSCO

In the Hi-VHF Band, you probably would want to receive Ch7 (MyN) and may or may not want Ch11 (Telemundo) depending on whether you understand Spanish. The NM for these is in the low 20's, so a "huge" Hi-VHF Antenna would be overkill. Much weaker Ch8 is a DUPLICATE NBC which you probably don't "need". Ditto VERY weak DUPLICATE NBC on Ch12.

Since a Full-VHF Band (Ch2-13) is HUGE, I'm going to hope you don't NEED it. So if you decide you WANT Ch3, I'm going to recommend you don't worry about it until you find a Hi-VHF Antenna is inadequate. At which point I would recommend adding a DIY Hourglass-Loop, designed for Ch3....and could be a FIXED Mount at a different location. Note that Wire Size is relatively unimportant, so easy to work (and rework) AWG12 or AWG10 will work just fine:
http://imageevent.com/holl_ands/loop...lassloopnorefl [NO Reflector]
http://imageevent.com/holl_ands/loop...ssloopreflrods [Re-Optimized for 3 Reflector Rods]
http://imageevent.com/holl_ands/loop...sloop5reflrods [Re-Optimized for 5 Reflector Rods]

Of course, there is a Hi-VHF Hourglass-Loop with Reflector Rods to increase Gain:
http://imageevent.com/holl_ands/loop...fhourglassloop

And Hi-VHF 2-Bay and 4-Bay Bowties with either Screen Grid or Reflector Rod Reflectors:
http://imageevent.com/holl_ands/multibay/hivhf2bayrefl
http://imageevent.com/holl_ands/mult...hf2bayreflrods
http://imageevent.com/holl_ands/multibay/hivhf4bayrefl

And several Hi-VHF Yagi's to chose from:
http://imageevent.com/holl_ands/yagis

However, I would suggest you simply BUY the 9-El Stellar Labs Hi-VHF Yagi:
http://www.mcmelectronics.com/product/30-2475
Which I analyzed here:
http://imageevent.com/holl_ands/yagi...agistellarlabs

Last edited by holl_ands; 02-24-2016 at 01:20 PM.
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post #4885 of 4899 Old 02-24-2016, 05:55 PM
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KSCO on Ch3 is strong enough that you MIGHT be receiving it already....and MIGHT receive it on an upgraded Hi-VHF Antenna. KSCO is an independent station with a heavy mix of news and talk, talk, talk:
https://en.wikipedia.org/wiki/KSCO

KSCO is an AM radio station. KCSO is Telemundo on RF 3 but it is being transmitted on KMMW RF 28 so KCSO on 3 is unnecessary. KCSO and KMMW are at the same site. The other low VHF stations KFTY (RF 2), KTVJ (RF4) and K02QX (now KQRO RF 2) all transmit the same 10 SD sub channels, mostly religious and shopping with North Bay TV on the .8 sub channel.

If you have a real low VHF antenna outdoors and not much noise those weak low VHF stations can be received. I receive KTVJ at 115 miles with about a 10 dB noise margin even though TV Fool predicts -3 dB NM. KFTY at 119 miles is slightly weaker. The temperature inversions affect low VHF less than high VHF and much less than UHF so the signal strength swings are less on low VHF.
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post #4886 of 4899 Old 02-24-2016, 08:20 PM
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You guys rock!
Right now I am satisfied. I use Netflix and Amazon Prime. And over the air we mostly watch cbs and local fox.
ABC is on real channel 10 here, good for football, when they run it.

I have learned a lot. Smart enough to realize what is beyond me also, and that is when ya'll become such a good resource.

I figured I saved a bunch of money with my home made.

Will likely be picking up roots again and heading out of state, Likely Kansas in the Leavenworth area. Not even the tiniest clue when. Irritates me that I will have to leave my creation that I am so proud of behind. But I can build another one and improved. I have most of the aluminum bits and pieces for it.

That bow tie vhf is a monster for sure. You are 100% correct holl_ands, Why build your own? $25 just makes that silly

Ken

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post #4887 of 4899 Old 02-24-2016, 09:07 PM
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I just for giggles checked out my step daughter's location in Leavenworth , Ks. It is rich in stations, all in the uhf range my FF6 (6-Bay) performs so good in. And heck half the distance that I am currently at.
Modesto
http://www.tvfool.com/?option=com_wr...51340d17ecbcc1

Leavenworth
http://www.tvfool.com/?option=com_wr...5134bef72e228c

Will keep this in mind.

Believe it or not I am hoping for some more bad weather so I can see how my antenna works in it.

Ken

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post #4888 of 4899 Old 02-25-2016, 07:48 AM
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Believe it or not I am hoping for some more bad weather so I can see how my antenna works in it.

I should write an article about this and add it to my web page instead of repeating it all the time.


Bad weather of any kind doesn't attenuate signals on UHF or VHF. Fair weather dominated with a high pressure like we're having now sets up temperature inversions over the valley that can bend signals and extend the range or enhance the signals. It was 59 degrees at my place last night at 2500' while it was in the 40's in the valley. Storms break up temperature inversions so any enhanced signals return to nominal levels. The best time to check your reception is during a storm. You should be able to receive everything you want at that time.
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post #4889 of 4899 Old 02-25-2016, 07:30 PM
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Then it would be much higher freaquencies that would be weather attenuated? Like maybe wi fi range?

I did notice today that pbs (real channel 9) dropped about 10 - 15 %. Real channel 10 was down about 5-10%.
Every uhf station was still at previous levels, around 97%


On a somewhat different subject, when I tore down the old 4 bay that I built maybe 5 or 6 months ago I did see a some amount of corrosion with dissimilar metal contact. Copper to aluminum, pennies (cheap washers) to hardware cloth. Galvanic reaction I quesse?

Ken

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post #4890 of 4899 Old 02-25-2016, 08:19 PM
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Then it would be much higher freaquencies that would be weather attenuated? Like maybe wi fi range?

No, not even wi-fi range. The satellite TV bands suffer from rain fade. The general rule is for significant rain fade the raindrops need to approach 1/4 wave of the operation frequency in diameter. At UHF TV that's about 5".
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