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Old 20-Oct-2011, 12:59 AM   #1
Jaytibee
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problem with one channel

I currently have a Winegard 7649 UHF/VHF anyenna with a pre-amp mounted about 30 feet above the ground on my roof. I live in Dublin, CA just outside San Francisco. I have aimed the antenna at azimuth 256 degrees clockwise from magnetic north.
I get over 70 channels with great reception and I get all the channels from Sutro tower with the exception of KTVU Channel 2 (fox).

Is there a reason I cannot get this channel when I am receiving all the others off the same tower ??

Any help on this subject would be greatly appreceiated

Thanks

John
Dublin, CA
Zip 94568
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Old 20-Oct-2011, 8:58 PM   #2
Jaytibee
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OTA problem

Live in the SF Bay area - get all channels from Sutro tower except Fox Channel 2 (KTVU) also on the tower

Have a winegard 7694 with AP 7800 pre-amp

Anyone have any suggestions why I cannot receive this channel also ??

John
Dublin, CA
Zip 94568
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Old 20-Oct-2011, 10:43 PM   #3
GroundUrMast
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It's tough to know what your situation is like with out seeing your TV Fool report. Please post a link... Guidlines when asking for help

Is your preamp a Winegard AP-8700? 'AP 7800' does not ring a bell with me.

With an accurate TVFR we can help more.
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Old 21-Oct-2011, 12:37 AM   #4
Jaytibee
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Thanks for the quick reply groundurmast

Here is the TVFR, hope it helps

http://www.tvfool.com/?option=com_wr...60b5c226d1d9eb

Actually I believe the TVFool data base may be incorrect for KTVU FOX (transmitting on 44.1, 2.1 virtual) - it was moved to Sutro Tower (in SF) in the 70s, but used to be located on the San Bruno mountain. Strange to say I pull-in good signals from San Bruno (az 150) with my antenna pointed at 260 az

You are correct, the pre-amp is winegard AP-8700 mounted 1 ft below top of antenna, I have one homerun into the house TV from the antenna, with no splitters.

The current active digital channels at Sutro tower are:
KBCW
KGO
KPIX
KRON
KTVU
KQED
KMTP
KCNS
KCSM
KFSF

I get all of these, except KTVU, KBCW.

See what you think it may be

Thanks
John
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Old 21-Oct-2011, 11:54 AM   #5
ADTech
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I don't see any error in TVFool's database for KTVU. Please note that San Bruno is only several miles south of Sutro resulting in a 10 degree spread of signals between Sutro and San Bruno as seen from Dublin. Az 150 most closely is in the direction of Mt Allison and Monument Peak which overlooks Milpitas.

You're working with severely diffracted signals at your location in Dublin. It appears you're about 1000' below a 1400' peak that is dead in your LOS to Sutro. Such locations often are far more varied than the somewhat simplified modelling offered by TVFool's modelling engine. Don't get me wrong, it's the best tool available to the public, but it does have limitations. Consequently it's estimates for diffracted signals may vary widely from actual conditions on the ground.

In situations such as yours, the first recommendation is to try a different mounting location. Sometimes, this alone will resolve problems, especially if you are encountering what I call "frequency-specific multi-path" in which an errant reflection affects either a single channel or a very narrow range of channels.

The next step, should relocation not be effective, would be to step up to a deep-fringe UHF antenna, either an 8-bay or a Yagi. Your antenna is intended to suburban or close-in work and the UHF section may be a bit insufficient for your particular conditions.
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Last edited by ADTech; 21-Oct-2011 at 12:01 PM.
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Old 21-Oct-2011, 6:08 PM   #6
Jaytibee
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Thank you ADtech

Yes - TVFool's modelling is extremely useful and has helped me a lot, but I must say that the KTVU location does not appear correct.

I am happy with the antenna that I have and cannot complain about the 70 didgital channels or so that I am receiving at my location, approx 18 miles from the towers.

The TV fool signal analysis does indicate that the KTVU station has an az of 150 from my location which would put it roughly due south. This does not agree with the actual sutro tower location channels which are in the az 250-260 range, roughly due west. Unless they have moved this station, something is amiss with the database, or I have a loose screw ! which has happened before.

I will confirm that KTVU is currently broadcasting from the Sutro tower.
Thanks for your time and I look forwarded to a continuing dialogue on this subject. I know signal analysis is highly subjective, but if others in the Bay area have experienced this irregularity from the sutro tower, then I would appreciate your comments

Thanks once again ADTech

John
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Old 21-Oct-2011, 6:14 PM   #7
Jaytibee
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See link below for active Sutro tower station list

http://sutrotower.com/about.html
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Old 21-Oct-2011, 6:15 PM   #8
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The FCC database lists the 'construction permit' for the RF 48 transmitter, which does not confirm if it's on the air or not. The most knowledgeable source would be the engineering staff at KTVU, who can confirm the status of the primary transmitter and any translators or fill-in transmitters.
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Old 22-Oct-2011, 12:41 AM   #9
ADTech
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KTVU operates it's primary facility from Mt Sutro.

The applied for and receid a construction permit to insta an RF 48 translator on Monument Peak. I have yet to see any evidence that it has ever been built and made operational. It's not an "error" in TVFool's database, it's just that the database is updated from the FCC's data which is often updated at government speed. Consequently, TVFool will show facilities for which a CP is issued without regard to whether it's actually on the air.
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Old 24-Oct-2011, 12:04 AM   #10
Jaytibee
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Dear Adtech

It would be better if you used "actual data" as its more reliable and less confusing, but I do still admire TVFool !. I'll adjust my azimuths accordingly to reflect the correct locations at Sutro. I'll check my other stations also for any ambiguity.

Thanks for your time and effort

OandO

John
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Old 25-Oct-2011, 12:50 AM   #11
Dave Loudin
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It's not ADTech's data, but information extracted from the FCC's database of broadcast facilities. What is contained therein better be "actual" data, as it reflects the legally permitted operations of stations. Any ambiguity comes from trying to show approved future plans (construction permits) to help future proof antennas. Problems with displayed data here can be traced to problems with the database extracts.
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Old 25-Oct-2011, 1:14 AM   #12
Jaytibee
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Then we have a problem between FCCs actual data and the physical presence of KTVUs antenna on Sutro tower. I believe what you may be referring to is the retrofit permits done before the digital upgrades in 2009.

Does not make sense to indicate physical data on TVF site based on future FCC plans, it just throws everyone off and gives erroneous azimuth data

They've only broadcast from this tower since 1972. I called their engineering staff last Friday to confirm.

Thanks for your time
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Old 25-Oct-2011, 2:53 AM   #13
Dave Loudin
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There is no problem, physically, with the location of the KTVU sites in TVFool. Here's what is in the FCC's database. If you click on the listings in the table of your report, you'll get the path profiles used in the predictions. Note that the coordinates agree, and the main facility is on Sutro.

Note that the fill-in translator carries the same call-sign as the parent. That greatly complicates tracking its status beyond what is notoriously tricky to know already. The only error here is including the fill-in in the active list. There is value in showing what's planned, as it may influence antenna choices.
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Old 6-Nov-2011, 3:50 AM   #14
rsuryase
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I have same problem. I use DVICO card and MegaWave MTV-1 antenna. FOX KTVU signal is only 25-50%. I don't get NBC at all.

http://www.tvfool.com/?option=com_wr...4bba02bc4f4865
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