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Author Topic: Transmit on 80 m knocks down DSL connection  (Read 1427 times)
W3TTT
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Posts: 30




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« on: February 12, 2012, 06:40:56 PM »

I have a new Icom 718 feeding directly into an 80m vertical with raised radials. 
When I transmit on 80 meters, my dsl connection is knocked down. 
I saw a topic in this forum from December 2001 on this issue, and it said it was probably due to rf in the shack, and to do all the usuall (rf filters on all the wires into the router) which I will do.
But does anyone have any new information since 2001?
Thanks
Joe w3ttt Smiley
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K8AC
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Posts: 1466




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« Reply #1 on: February 13, 2012, 11:00:17 AM »

Check the RFI forum. There have been recent discussions on the subject.  I believe that there are some improved DSL modems that are less susceptible to the problem.  Apparently, some ISPs are now able and willing to address the problem with you and it might be worth calling them.
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KC9TNH
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Posts: 304




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« Reply #2 on: February 13, 2012, 11:05:09 AM »

I recently went down this rabbit hole in prep for getting internet into the house for my Chief of Staff (and having a dipole right over the entry point to the house).  (not sure you necessarily have RF in the shack, sometimes devices can be sensitive to specific bands or even frequencies, a discovery the hard way) Some of it may not apply directly to your DSL situation but may lead you to something.

2 things I did have (so far) resulted in peaceful coexistence:

1.  Type 31 choke on the internet line (RG-6 in this case) as soon as it enters the house, as well as one outside. Yeah, I know, but it got rid of the wavy lines on the Mrs' TV while on 20m.
2.  Insistent (like a junkyard dog) on the internet provider's installers bringing someone along that no-kidding knows the craft in their industry and how to properly implement a ground once their hardline from their pedestal breaks out of the ground to enter the house as "normal" coax. If your service is provided by the phone company, request that the phone company check the integrity of the grounding they're supposed to do in the first place.

I'd go around and check the ground on the internet connection; try some decent HF chokes, if you want to put one on the router point you can try that as well.
Q:  Do you have any wired connections into the router where you've used a SHIELDED twisted-pair cable? In some cases regular unshielded twisted-pair works better, letting the twist do its job.
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73
Wes -KC9TNH
"Don't get treed by a chihuahua." - Pete
NO9E
Member

Posts: 395




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« Reply #3 on: February 13, 2012, 11:43:41 AM »

I spent a few months trying U-Verse to coexist with transmit 160 and 80m. All solutions were short lived. I am back to cable.  My experiences are not unique.
Ignacy
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AB9TA
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Posts: 20




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« Reply #4 on: February 13, 2012, 08:25:59 PM »

It just seems to be something about 80M.. I have the same trouble here with the cable internet. Both the dipole and vertical will cause the problem.
It shuts down the wireless router which also has wired connections to the PC's in the house. I've tried all the filtering, ferrites, and stuff I can think of, no joy.
But, as long as I stay at or under 15W, I'm OK.. No worries as I mostly run digital modes, it's not much of a handicap.
I just make sure the XYL isn't working or otherwise on the computer.. Satellite TV is unaffected.
I do sometimes wonder if the neighbors are affected..

73!
Bill AB9TA
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TANAKASAN
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Posts: 933




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« Reply #5 on: February 14, 2012, 01:53:40 AM »

Been there, done that.

1) Find out where the interference is entering the router. Disconnect everything except the power line and the phone line then get someone to watch the LEDs as you transmit. If you still knock out the DSL connection then your problem is either the power or the phone line, fit ferrite chokes to the leads.

2) Reconnect your network plugs one by one in an attempt to find which data line is carrying the interference, you may find that one of them is a resonant length on 80m. Shielded twisted pair MAY help but this isn't guaranteed, ferrite chokes may help.

Tanakasan
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KE3WD
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Posts: 5694




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« Reply #6 on: February 14, 2012, 08:05:01 AM »

And place a proper balun at the feedpoint of the aerial...

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W4VR
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Posts: 1194


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« Reply #7 on: February 14, 2012, 08:08:29 AM »

i had the same problem and my antennas were 100 feet away from the modem and phone lines coming into the house.  I tried filtering with ferrite beads to no avail.  I finally gave up and terminated my DSL contract with the phone company and switched to a Wi-Max service....no problems with RFI since I've done that.
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MM0ZBH
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Posts: 18




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« Reply #8 on: February 14, 2012, 03:53:10 PM »

UK DSL knocked out on 40m with about 50w ssb at my qth on the G5RV which admitted was 'close' to the overhead phone lines.  No other bands caused any issues.

Switched to a 1/4 vert for 40m in the front garden, the problem went away and the DX got better....!!
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N4NYY
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Posts: 4749




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« Reply #9 on: February 14, 2012, 05:40:39 PM »

One of the guys in my club has the same problem running barefoot. This Verizon DSL modems are crap! The same setup did not happen with Comcast.
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G8JNJ
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Posts: 487


WWW

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« Reply #10 on: February 15, 2012, 12:47:08 AM »

HI All,

I resolved my difficulties with UK ADSL by installing suitable ferrite chokes to the router cables.

My observation is that most folks don't use enough ferrite (or the correct type) to be effective in the 2 - 4MHz frequency range, where the ADSL signal is most succeptable to external interference.

I can run 100W on 160, 80 & 40m with a loft mounted antenna running parallel to the phone line at a spacing of about 6 to 10ft. With no problems on TX or noise on RX.

My notes can be found here.

http://g8jnj.webs.com/EMC%20and%20Amateur%20radio.pdf

Regards,

Martin - G8JNJ

www.g8jnj.webs.com
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