Author Topic: Local RFI (Read 21816 times)

Wrightwood · « **on:** Jun 23, 05, 05:03:51 PM »

I decided to take a few pictures of cable tv lines in the neighborhood to see if they might be the culprit to our radio frequency interference.

Sure was a lot of loose wires that don't appear to be terminated.

Chesslike · « **Reply #1 on:** Jun 23, 05, 05:18:33 PM »

The loose wires appear to ones that are going to people's houses who no longer have active cable and should not have any signals going through them. You should probably be concerned if the junction boxes are properly terminated so they don't leak a signal. Does Clint have any equipment that tests for signal leakage?

Wrightwood · « **Reply #2 on:** Jun 23, 05, 06:23:54 PM »

I know there are some loose wires running towards the houses and who knows what is taking place in people's houses.

My biggest concern is the un-terminated cable company wires. Look at the top two photos and the last one and you'll see loose wires coming right out of the cable companies distribution box. And in the first photo, what's the big cut wire end that looks like coax that's hanging there?

I should have mentioned that I only walked a few hundred feet in the neighborhood and found a number of suspicious spots. Since Clint has determined that the RFI exists down Linnet and then Thrush it's possible that more areas will be found when we get a chance to walk the entire area.

Wrightwood · « **Reply #3 on:** Jun 23, 05, 06:59:20 PM »

The frequency of the noise being generated is at ~~125.250~~ 145.250.

Here's some additional information:

http://www.arrl.org/tis/info/rfigen.html

SNOW · « **Reply #4 on:** Jun 23, 05, 11:58:19 PM »

Is this the same signal that Clint mentioned to me regarding Thrush? I found a hot spot on Thrush, midway between Dogwood and Sheep Creek. The frequency is 145.25.

Looking at a chart found on:
http://www.arrl.org/tis/info/HTML/catvi/index.html

I wonder if this could be the source of the RFI in that area.

Problem Channels for Amateur Radio Operators
Channel* CATV Video Carrier Sound Carrier

Cable 18 E 145.25 149.75

SNOW · « **Reply #5 on:** Jun 24, 05, 08:47:22 AM »

Thank you for posting the link, John, it is a 'gold mine' of information.

Wrightwood · « **Reply #6 on:** Jun 24, 05, 09:09:58 AM »

Jack,
This interference has been an issue for years in this neighborhood.

We will be drafting a letter to Charter Cable soon and informing them that their lines may be the cause of severe RFI throughout the area. The appropriate FCC Part-15 Rules will be cited and we'd like to get to get the OK of local hams to include their calls signs on the signature line.

SNOW · « **Reply #7 on:** Jun 24, 05, 10:35:06 PM »

It would be interesting to see if the audio carrier frequency, 149.75, is also present at the RFI hot spot on Thrush. That could be a very good indication that there may be leakage from the cable system.

Wrightwood · « **Reply #8 on:** Jun 25, 05, 09:33:04 AM »

Clint worked on the issue again this morning and located a distribution amp for the cable company on Thrush near Dogwood that has major problems. You can stand 15 feet from amp and pickup a cooking channel on a receiver.

In another spot on Sheep Creek & Thrush is a 20 foot piece of un-terminated coax hanging onto the ground.

clint · « **Reply #9 on:** Jun 25, 05, 03:14:33 PM »

And yes Jack, the audio channel of 149.75 is full quieting into an HT at the distribution amp. And the scanner with 500 ohms of attenuation will still open squelch on 145.250 at the amp. So it looks like we found the originating source.

SNOW · « **Reply #10 on:** Jun 25, 05, 04:40:43 PM »

Good job, guys. Sounds like the smoking gun to me. This may be just what we need to get the cable company's attention.

clint · « **Reply #11 on:** Jun 25, 05, 07:17:05 PM »

I would like to do one more test into a step attenuator (which I have to build) so we can give the FCC inspector hard numbers. That makes a big difference in these matters.

SNOW · « **Reply #12 on:** Jul 15, 05, 03:56:14 PM »

Wrightwood · « **Reply #13 on:** Jul 15, 05, 05:42:54 PM »

Good job Jack. The article sure sounds like a match to our problem.

Sounds like the cable is the place to start.

Wrightwood · « **Reply #14 on:** Nov 08, 05, 09:55:43 PM »

Toolman,
There's more details in this forum about our serious RFI issue.

We know for sure that it's present on the streets listed but suspect many other areas have issues. There's hanging - unterminated connectors all over town.

RobertW · « **Reply #15 on:** Nov 08, 05, 10:27:40 PM »

Wrightwood · « **Reply #16 on:** Nov 08, 05, 10:29:39 PM »

When I was up on Rivera a week or so back I happen to look up and it appear to be a clone of what I've seen around here.

Toolman · « **Reply #17 on:** Nov 09, 05, 06:41:59 AM »

Thanks John for letting me in

Wow...what a mess the cable company has. Does anyone have access to a spectrum analyzer? A couple hrs. worth of readings and a print out of the data along with the photo's sent to the FCC would/should get the message across.

WB6K

SNOW · « **Reply #18 on:** Oct 12, 06, 11:49:37 PM »

Has the interferrence from the cable distribution amplifier on Thrush near Dogwood been resolved? Was the letter to the cable company sent and did they respond in a timely manner?

Wrightwood · « **Reply #19 on:** Oct 13, 06, 12:00:29 AM »

unfortunately....
No, No and No

Author Topic: Local RFI (Read 21816 times)

Chesslike

clint

clint