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Old 21-Feb-2014, 2:09 PM   #1
Desert Rat
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Join Date: Feb 2014
Posts: 5
Help with deep fringe reception Tucson to Phoenix

Hello, I'm new to TV Fool and have found this site and the tools to be fantanstic. Thanks for all your expert help.

My map:
http://www.tvfool.com/?option=com_wr...5b940fbea50b5a

My Location:
NW Tucson, AZ

My problem:
I've been receiving OTA all the major networks and Tucson channels for years with a good sized VHF/UHF antenna in my attic. The only problem in NW Tucson is that we are shadowed to the transmitters on Mt Bigelow to the east where most of the major network transmitters are located. Because of this ABC, NBC and CBS have rebroadcasting translators to the south of Tucson. The problem is FOX, channel 11 does not have an alternate transmitter. Years ago before digital I could pick up Ch 11 with a rooftop antenna, cut for VHF 11, and a preamp. But the preamp is long gone and Ch 11 now broadcasts on RF 25. I still have a decent UHF antenna on the roof but can't get Ch 11 on 25, especially without a preamp. I thought I would give Phoenix a try and pointed my rooftop UHF towards Phoenix. It is a straight shot 90 miles up I10 to south mountain without any noticeable obstructions. I did a scan and wow! I picked up about 15 Phoenix stations including FOX Ch 10. (BTW, FOX 10 broadcasts on RF 10 but I found it on 10.2 RF 26, not listed on my TV Fool report, but found here http://www.ask.com/wiki/List_of_tele...ons_in_Arizona).

I thought all was good until I went to watch the superbowl on FOX and found all the Phoenix channels GONE! I messed around with the antenna, cabling, connections, direction, etc. all to no avail. Later I discovered all the channels come in fine late at night and in the morning and disappear around 11am. From what I have read this may be due to some tropospheric conditions that change as the desert heats up during the day. I'm thinking a better antenna or preamp may be needed to boost the gain enough to get past these conditions. Is there a better antenna that you believe could help? Preferrably without a preamp. Or other suggestions? I don't believe I need VHF since I can get Ch 10 on RF26.

My current rooftop UHF is a 30 year old, maybe winegard, at 21 ft. IMAG1754smaller.jpg

Thanks!
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Old 21-Feb-2014, 4:59 PM   #2
stvcmty
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Join Date: Mar 2013
Posts: 135
How many TV’s are you feeding?
How long is the cable from the antenna to the TV(s)?
What ground blocks, splitters, junctions, wall plates, etc. are between the antenna and the TV’s.
With the low signal strength for the phoenix stations, cable losses need to be carefully weighed against noise from a preamp. (I know you said preferably without a preamp, but if you have more than 3dB of losses, the right preamp could make a positive difference.)
Which Phoenix stations do you want? The best antenna for RF15 may not be the best antenna for RF51.
(The fox station you are getting on RF26 is SD; look at KUTP on rabbit ears. http://www.rabbitears.info/market.ph...&callsign=kutp )
If fox is your white whale, you could chase it on RF25, RF26 (in SD), or RF10. For RF25 or 26, either would be in the range where the 422HD or the HD8800 have the best gain (as modeled by http://www.hdtvprimer.com/ANTENNAS/comparing.html ). If you want to go after RF10, you could try a Y10-7-13.

(I have never captured a VHF channel with a negative noise margin, but I have gotten several UHF stations with negative modeled noise margins. That probably has something to do with it being easier to make a high gain UHF antenna that is a reasonable size.)
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Old 21-Feb-2014, 7:16 PM   #3
teleview
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+=>
----
The Phoenix Tv stations are 80 Pluse miles away , are very low signal strength and have 2 Edge path obstructions = hills and mountains.

For reception of what will be received from Phoenix.

A Big antenna is required.

Install a www.antennacraft.net , HBU55 antenna aimed at about 311 degree magnetic compass direction.
Here is how to aim antennas , www.kyes.com/antenna/pointing/pointing.html

Use a Real and Actual magnetic compass to aim antenna.

Install a , RCA TVPRAMP1R , preamplifier.

Connect to 1 Tv only , No splitters , for the Testing of reception of the Phoenix Tv stations.

----------------------

For reception of FOX Tucson.

Install a NEW matching transformer (balun) to the UHF antenna and run a NEW coax form the New matching transformer through a open door or window direct to 1 Tv.

Tilt the front of the UHF antenna up and aim at the top of the mountain where the Fox transmitter is , scan for channels , is Fox received now??

Also can aim the UHF antenna at the surrounding mountains to find a mountain that provides a strong reflected signal of the FOX transmitter.

------------

Also , Digital Tuners can develop - Digital Glitches - that are not cleared out with simple channel scans.

To clear tuner do Double Rescan.

www.wchstv.com/DoubleReScanAlert.pdf

Last edited by teleview; 24-Feb-2014 at 2:03 AM. Reason: Clarify information and typos.
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Old 21-Feb-2014, 8:06 PM   #4
StephanieS
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Join Date: Aug 2012
Posts: 442
Hi Desert Rat,

Your Phoenix stations are extremely weak according to your tvfool. When signals are right on that edge of reception, they can come and go. Where you'll notice this is during daylight hours. If at night they are stable and 10 or 11 in the morning they vanish till 6 or 7pm they are showing symptoms of what the atmosphere can do to TV signals that are very weak, the more active atmosphere is too much for the signals and they fall below reception threshold. I have a signal that is about 7db. Without my preamp in service, it vanishes for most of the daylight hours. The preamp has helped reduce that just to occasional freezes or 1 or 2 second drop outs during middays.

Your situation with FOX is unfortunate. If I were in your situation, I would swap you antenna for a two antenna situation.

First Antenna: Channel Master 4228HD: http://www.solidsignal.com/pview.asp?p=4228-hd. This recommended over the DB8 due to having a bit nicer gain in the channels below 35. It is also for UHF only (real channels 14 and up)

Second Antenna: Antennacraft Y10-7-13[. http://www.solidsignal.com/pview.asp...-7-13&ss=31606. This antenna is for high-VHF only (real channels 7-13).

You also need a combiner. The Antennas Direct EU385CF-1 signal combiner is a nice unit. http://www.solidsignal.com/pview.asp...CF-1S&ss=31614. This does what it says, literally. It takes your 4228 and Y10-7-13 and instead of two coaxes combines them into one. Thus, your 4228 coax will go into the UHF input while the Y10-7-13 coax will go into the VHF input, hook into your exist download into the "output" connector.

You can test a preamp, it may or not work as planned. With preamps, if you have strong signals nearby, such as KHRR RF 40, you can actually lose reception to overloading your tuner. If this happens, remove preamp.

Overall, this is what I would do to go after FOX. It still may not be reliable, but it gives you the best chance. With your 2-edge conditions for magnetic 65's towers, you need a UHF antenna with more surface area.

When mounting, make sure to have 4' of space between antennas on mast.

Cheers.

Last edited by StephanieS; 21-Feb-2014 at 8:09 PM.
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Old 22-Feb-2014, 2:48 AM   #5
technicolor
Junior Member
 
Join Date: Jan 2014
Posts: 14
Quote:
Originally Posted by Desert Rat View Post
Hello, I'm new to TV Fool and have found this site and the tools to be fantanstic. Thanks for all your expert help.

My map:
http://www.tvfool.com/?option=com_wr...5b940fbea50b5a

My Location:
NW Tucson, AZ

My problem:
I've been receiving OTA all the major networks and Tucson channels for years with a good sized VHF/UHF antenna in my attic. The only problem in NW Tucson is that we are shadowed to the transmitters on Mt Bigelow to the east where most of the major network transmitters are located. Because of this ABC, NBC and CBS have rebroadcasting translators to the south of Tucson. The problem is FOX, channel 11 does not have an alternate transmitter. Years ago before digital I could pick up Ch 11 with a rooftop antenna, cut for VHF 11, and a preamp. But the preamp is long gone and Ch 11 now broadcasts on RF 25. I still have a decent UHF antenna on the roof but can't get Ch 11 on 25, especially without a preamp. I thought I would give Phoenix a try and pointed my rooftop UHF towards Phoenix. It is a straight shot 90 miles up I10 to south mountain without any noticeable obstructions. I did a scan and wow! I picked up about 15 Phoenix stations including FOX Ch 10. (BTW, FOX 10 broadcasts on RF 10 but I found it on 10.2 RF 26, not listed on my TV Fool report, but found here http://www.ask.com/wiki/List_of_tele...ons_in_Arizona).

I thought all was good until I went to watch the superbowl on FOX and found all the Phoenix channels GONE! I messed around with the antenna, cabling, connections, direction, etc. all to no avail. Later I discovered all the channels come in fine late at night and in the morning and disappear around 11am. From what I have read this may be due to some tropospheric conditions that change as the desert heats up during the day. I'm thinking a better antenna or preamp may be needed to boost the gain enough to get past these conditions. Is there a better antenna that you believe could help? Preferrably without a preamp. Or other suggestions? I don't believe I need VHF since I can get Ch 10 on RF26.

My current rooftop UHF is a 30 year old, maybe winegard, at 21 ft. Attachment 691

Thanks!

Get a quality preamp from antennacraft. If this does not solve your issue, it will not be money wasted.
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Old 22-Feb-2014, 3:03 PM   #6
Desert Rat
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Join Date: Feb 2014
Posts: 5
Thanks for the help.

It's a bummer that Phoenix 10.2 RF26 is SD. I'm thinking now since Phoenix HD FOX10 is VHF that maybe I should go for Tucson FOX 11 on RF 25 since it sounds like deep fringe VHF is more difficult. But I know if I can get Tucson 11 at all it will likely need a preamp. And many of the other Tucson stations are very strong, so I'll probably have saturation issues with the preamp.


STVCMTY
Currently i am only running one TV but may want to add 1 or two more in the future. My cable length from the antenna on the roof is 30 ft of RG6 that connects to about 20 more feet of coax in the wall (30 yrs old, presumably RG59). No other ground blocks, splitters or combiners yet.

StephanieS
Thanks for the antenna recommendations. I could go with the two antennas as you suggest, and just use my rotator to swing from Phoenix to Tucson stations. Otherwise my plan was to just keep the attic antenna for Tucson stations and use a specialized rooftop setup for FOX out of Phoenix. If I go that route I will only need UHF or VHF, but not both depending on which FOX station I'm trying to receive (10 or 26).
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Old 29-Dec-2014, 12:11 PM   #7
Desert Rat
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Join Date: Feb 2014
Posts: 5
With some time off from work over the holidays I was finally able to get back to this project of trying to receive Fox Ch 11, RF 25, from Mt Bigelow in Tucson. Thanks for all your recommendations, I believe I used most all of them and have some good news, and some weird news.

First I purchased an RCA TVPRAMP1R preamplifier and installed it with my existing rooftop UHF antenna. I tried different aim points, both horizontally and vertically. No sign of Ch 11.

Next I purchased a CM4228HD and installed it with the preamp on the roof in place of my old UHF antenna. Again I tried many aim points with no success.

I was ready to give up, but thought I would give it one last attempt using more of your recommendations. I removed the antenna from the roof, hooked up a new shorter coax with the preamp, and used a smaller TV that I could take in my backyard that faces the mountains where the transmitters are located. With everything on the ground and the antenna facing the mountain I did a scan, and WOW! Immaculate reception! I'm now getting channel 11.

The next step was to determine what was now allowing me to receive a decent signal. Was it the new shorter coax with no splitters, a different TV, antenna location, etc. Any guesses?

I'll spare you all the trial and error, but it turned out to be the antenna location. I thought if I could receive a good signal with the antenna on the ground it would be even better if I could find the ultimate spot on the roof. So I tried various spots on the roof and even attached the antenna to a mast that I could move around manually trying different locations, heights and aim points. Turns out it would not work at all anywhere above 5-6 feet. In fact it would not work as well even raised 2-3 ft. off the floor of my back porch. But sitting directly on the concrete facing the mountain I could get 71% on the strength meter. Ok, it's getting weird now.

I went back to the TV Fool report, and sure enough, if I put in 1 ft. antenna height it gives me better numbers than 10 or 20 feet. 1 ft. = +4.5 db, 10 ft. = -0.7 db, 20 ft = -1.3 db. So apparently the TV Fool calculations knows about this weirdness. I did some searching on this and best I could find is that sometimes with 2 edge signals and mountains you can get a phenomenon where the RF signals will travel along the ground following the terrain. OoooK. It's true, antennas and RF are a little bit voodoo.

I reconnected to my standard house cables, splitter and big TV and it all works with the same good signal strength, as long as the antenna is on the ground.

Now I have to figure out the best way to setup the CM4228 on the concrete floor of my back porch. Any thoughts on mounting an antenna to sit on the floor, or any other tests I should try would be appreciated.

Thanks again for all your help and suggestions. This is truly a good service you provide.

Last edited by Desert Rat; 29-Dec-2014 at 4:17 PM. Reason: typo
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Old 29-Dec-2014, 10:42 PM   #8
Tower Guy
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Location: Delmar, NY
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Quote:
Originally Posted by Desert Rat View Post
Turns out it would not work at all anywhere above 5-6 feet.

I went back to the TV Fool report, and sure enough, if I put in 1 ft. antenna height it gives me better numbers than 10 or 20 feet.
The formula used to calculate signal strength in TVfool does not use ground reflections to figure signal strength. Yet ground reflections can add up to 6 db to the signal strength.

Read the paragraph "Average Power Diagram for UHF" in the following web site:

http://www.hdtvprimer.com/antennas/siting.html

In your case, the signal enhancement near the ground is even more pronounced than the picture shows. I'd assume that the TVfool calculation of a stronger signal at ground level is a coincidence.

Consider an old umbrella stand for your mounting pole. Others use concrete in a 5 gallon plastic pail.
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