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Thread: Houston, we have a problem.

  1. #1
    Join Date
    May 2008
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    Default Houston, we have a problem.

    My local cell site, about 3/4 mile to my southwest ...
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    ...has recently added some new equipment.

    Since then, it has been wiping out many UHF channels...
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    ...This is what my most local TV station WKMU 36/21 (10 miles from here) looks like since the addition of the new equipment at the cell site.

    WKMU signal prior to new cell site equipment...
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    WKMU signal after new cell site equipment...
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    Are you sure you want that cell phone stuck to your ear all day?...
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    Many UHF channels are now unusable between 210 and 240 degrees azimuth. This used to be a very productive direction for UHF tropo. Not any more.

    Oh well, it was fun while it lasted.

    73, Ed NN2E
    Owner / Operator - Murphy's Law Test Site & Thunderstorm Proving Grounds
    Last edited by NN2E; 06-26-2013 at 02:05 PM.
    "You Might Be a Redneck If...
    Your TV is on 24/7.
    Your TV has been permanently on for over a decade.
    The only time your TV is off is during a power outage.
    Your TV gets 512 channels, but you go outside to use the bathroom.
    Your new TV is sitting on top of your old TV.
    Your TV costs more than all of your other furniture.
    Your deer-stand has a TV antenna on it.
    Your cable provider has no idea that you exist."
    Jeff Foxworthy

  2. #2
    Join Date
    Mar 2007
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    Pembroke Pines, FL, USA
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    Default

    That is terrible. DXers are low on the priority list.

    cd

  3. #3
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    May 2007
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    Line of sight to all Hartford, CT TX's.
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    Default

    It might be worth a call to the local TV station of the FCC. It's one thing when legal RF transmissions interfere with DXing but LOCAL TV reception - that should be something the FCC would want corrected.

    Bill

  4. #4
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    Jul 2005
    Location
    Indianapolis, IN
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    Default

    I would definitely file a complaint with the FCC (Moe, Larry and Curly) and notify every local area TV station that this new equipment is interfering with. When this equipment is totally disrupting reception of a local station @ 10 miles there is a real problem. And, yes, we may soon have a large portion of our population with issues like brain tumors and brain cancer. Some people seem to have a cell phone stuck to their ear 24/7. Not good.

  5. #5
    Join Date
    Jul 2005
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    Shreveport, LA
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    Default

    Ed, I agree with Bill and Steve about the FCC.

    That is a remarkable difference in signal.
    Danny
    Shreveport, LA
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  6. #6
    Join Date
    Jul 2011
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    Default

    ECPA, we have a problem.

  7. #7
    Join Date
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    Northern NY
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    Default

    Quote Originally Posted by indysteve View Post
    I would definitely file a complaint with the FCC (Moe, Larry and Curly) and notify every local area TV station that this new equipment is interfering with. When this equipment is totally disrupting reception of a local station @ 10 miles there is a real problem. And, yes, we may soon have a large portion of our population with issues like brain tumors and brain cancer. Some people seem to have a cell phone stuck to their ear 24/7. Not good.
    I try to avoid holding my cell phone up to my head as much as possible. I either use speakerphone or plug in headphones, I can hear the call much better through headphones than that tiny speaker on most cell phones.

    I imagine the new equipment is for 4G LTE around 700mhz. But it shouldn't be putting emissions all over the UHF band. Right near a cell tower the signal on my phone maxes at about -60dBm so cell towers aren't that powerful. There is no reason for them to be very powerful since they are limited by the phone's ability to transmit back. Hopefully the equipment installation isn't finished yet and the issue will get fixed.
    DX Radios:
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    Sony XDR-S10HDiP
    Tecsun PL-390

  8. #8
    Join Date
    May 2008
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    Thunderstorm, KY
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    Default

    I don't own a cell phone and I hope I never do.

    I've spent the past couple of days playing answering machine tag with the cell site manager. I'm hoping, eventually, I'll actually get to talk to him and find out just what has been added to the site. Once I know it's frequency of operation I can start to figure out how to deal with it.

    However...

    ...The CM-7777 pre-amp I'm using was designed to amplify TV signals way beyond channel 51. Since, now, there's no regular DTV broadcast above channel 51 (just under 700 MCs) this opens the door for gremlins. If the cell site is running any transmitters in the 700+ MC range, this RF gets into the pre-amp which amplifies the Hell out of it. The DTV box just can't deal with all this unnecessary RF crud. So, I'm looking into using a low-pass filter with a sharp cut-off above 700 MCs. If the filter is installed between the antenna & pre-amp this should drastically reduce the amount of RF crud being delivered to the pre-amp and, in turn, to the DTV box.

    ...Just thinking out loud here... without all the necessary info... so don't bet the ranch on this.

    I'll know more when I know more.

    73, Ed NN2E
    Owner / Operator - Murphy's Law Test Site & Thunderstorm Proving Grounds
    "You Might Be a Redneck If...
    Your TV is on 24/7.
    Your TV has been permanently on for over a decade.
    The only time your TV is off is during a power outage.
    Your TV gets 512 channels, but you go outside to use the bathroom.
    Your new TV is sitting on top of your old TV.
    Your TV costs more than all of your other furniture.
    Your deer-stand has a TV antenna on it.
    Your cable provider has no idea that you exist."
    Jeff Foxworthy

  9. #9
    Join Date
    Jul 2009
    Location
    Northern NY
    Posts
    642

    Default

    Have you tried without the pre-amp to see if your locals come in better. If you can narrow down the issue to your pre-amp amplifying the noise above 700Mhz than perhaps a low pass filter would work. Its very likely that the equipment they added was 4G LTE which broadcasts around 700Mhz. I was looking around the internet to see if anyone made a 700Mhz low pass filter with F connectors and found that Radioshack makes a 4G LTE filter with coax connectors that is a 700Mhz low pass filter. I guess you are not the only one with this issue.

    https://www.radioshack.com/product/i...uctId=12934420
    DX Radios:
    Sony XDR-F1HD
    Sony XDR-S10HDiP
    Tecsun PL-390

  10. #10
    Join Date
    May 2008
    Location
    Thunderstorm, KY
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    Default

    (spunker88... I was typing this up just before you posted... seems we're thinking along the same lines)

    If you want it done right, ya gotta do it yourself....

    Tired of playing phone tag with the cell site manager I decided to do a little exploring with the Icom R-7000. I aimed the antennas at the cell site, unplugged the pre-amp power supply (this provides a ton of attenuation) and started up from 700 MCs. Didn't take too long before, there it was, a 10 megacycle wide swath of digital bedlam from roughly 746 to 756 MCs. This is what used to be channels 60, 61 and most of 62. It would seem the, "too much unnecessary RF crud in the pre-amp" theory might be correct.

    I guess it's time to look closely at low-pass filter specs and pick the best one for chopping off everything above 700 MCs. (channel 51)

    So far... I've looked at the Microwave Filter Company model 3322...

    http://www.microwavefilter.com/lowhighpass.htm

    ... but I'll check out the Rad-Shack filter. Thanks for the link.

    73, Ed NN2E
    Owner / Operator - Murphy's Law Test Site & Thunderstorm Proving Grounds
    Last edited by NN2E; 06-28-2013 at 09:54 AM.
    "You Might Be a Redneck If...
    Your TV is on 24/7.
    Your TV has been permanently on for over a decade.
    The only time your TV is off is during a power outage.
    Your TV gets 512 channels, but you go outside to use the bathroom.
    Your new TV is sitting on top of your old TV.
    Your TV costs more than all of your other furniture.
    Your deer-stand has a TV antenna on it.
    Your cable provider has no idea that you exist."
    Jeff Foxworthy

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