WPI (Water Pipe Interference)

[W5AMI]

Interesting thread on another list I belong to:

I need advice or a lead on Water Pipe Interference (WPI). This is not a joke. At midnight my wife and son came into the room while I was transmitting on 3.9000 MHz stating that someone or thing  is under the house hitting the pipes or dragging chains. My son and I, carrying shovels, walked the perimeter to find all the vents and crawl space covers in place. I went to the shack to resume transmitting while my son listened. He came in to say the water pipes were vibrating. I had him transmit while I looked and I could see the 3/4 inch water pipe moving rapidly back and forth in 1/2 inch cycles. I'm planning on clamping the pipes to the framing but wonder if that solution could lead to further problems. Has anyone had similar experience or information on this issue? I live near Los Angeles and have great signal reports from all the Western states. I'm running resonant inverted Vs with nearly a 1:1 match fed through a balun and RG213. The SDR1000 is driving an AL-82 with at
 least 1K Watts out and each piece of equipment is grounded to a 3/4 inch copper pipe running through the shack and leading to the copper water pipes 30 feet away. I have no TVI, RFI just WPI.

[Pete, WA2CWA]

I saw that post.
With his high power, he probably has the audio gain set too high, with too much compression, and probably toooo much low frequency response that’s causing the adjacent electrons in the surrounding air around his coax to vibrate excessively and then propagating to the water pipe causing it to vibrate, as it tries to find resonance. Well-known problem in the contest arena, which besides vibrating pipes, can also include teeth rattling, shaking pictures, and skinny people becoming spastic.

[W5AMI]

Well-known problem in the contest arena, which besides vibrating pipes, can also include teeth rattling, shaking pictures, and skinny people becoming spastic.

HeeHee

Here is a funny follow-up post on that thread:

Hi Jerry,


WPI happens much more frequently with Software
Defined Radios than with conventional transmitters.
We will have a WPI Flooring Filter in an upcoming
version that you can download via the SVN.

The sampling artifacts induce the vibrations.
Interestingly, Lower Side Band seems to affect
cold water pipes more frequently and Upper Side
Band vibrates the hot water pipes.  There was an
issue with spread-spectrum and sewer pipes, but
that was fixed as soon as it showed up.

In the meantime, while you are transmitting,
open a faucet in the house a slight amount so
that you have drips.  Drip size does not matter,
but the number of drips per second (DPS) should
be an integral multiple of the frequency you are
on in Megahertz.


Sorry, fellows, I couldn't resist.   

[k4kyv]

When I used to live in the Boston area, I had an apartment in one of those old wooden three-decker firetraps.  I ran about 450 watts DC input, plate modulated.  The antenna was an end-fed zepp running  from the rooftop of the apartment bldg to a tree across the street. 

I sometimes had rfi problems, particularly with solid-state stereo component systems.  One night, I was operating at about 2 AM, when I got a phone call from the guy in another apartment in the same building.  He said  that he was used to hearing me coming thru his stereo, but that time he had a sick friend staying over, and the friend was crashing in his living room floor until he recovered from his illness.  The friend was having trouble sleeping because my voice was clearly audible, with the sound coming right out of the wall.  The only thing I could think of was rectification at a corroded pipe joint in the building's plumbing system, since that wall was nowhere near my radio room.

I remember Otis, K5SWK in Houston, telling about the superstitious Mexican lady who lived next door.  One evening he was on the air, and the  lady came knocking on his door, with a frightened look on her face.  She told him she heard voices coming out of her electric stove oven, and she thought it was an evil spirit, and asked him to come over and see if he could chase it away.

In the past I have got into my own electric stove oven, so I suspect the lady really was hearing voices when Otis transmitted.

I can't explain the shaking pipe phenomenon.  But I'd bet the audiophool community could come up with some interesting theories, though.

[Bacon, WA3WDR]

Modulation from my first amateur AM station, 120 watts carrier input, used to be audible from the junction of a rusty mounting strap and a pipe in the basement.  If I recall, the strap held something else up, and a bent-over end of the steel strap was touching the gas pipe.  I bent the offending piece of strap away from the gas pipe, and the sound went away.  That was wierd.  And not good - little sparks to a gas pipe.  EEEK!

If the pipe is shaking, it might be that RF is turning a valve or pump on and off.

[KB2WIG]

Bacon, U was straping w/ 120W(in)    klc








Yes, I am on narcotics.

[W5AMI]

If the pipe is shaking, it might be that RF is turning a valve or pump on and off.

I'm curious to find out if it only shakes when audio is applied, however I think he's already fixed most of it by attaching an additional ground at one end of the pipe.

[Bacon, WA3WDR]

Bacon, U was straping w/ 120W(in)    klc

Heh heh, not THAT kind of strapping...

[W1RKW]

I have noisy neighbors who like to loud play music til late at night.  I'd love to have one of their pipes experience WPI especially a toilet.  That would be cool.

[KB2WIG]

Is the music recorded or is it live? I've found that a GDO is great for the radio... Most of the consumer stuff is plastic. All you do is read the ARRL guidelines for elimination of RFI in this stuff.  Learn from the hobby, and share with your neighbor.....   You have a transmitter. Use it. 


klc





 Yes, I am on narcotics.

[W1RKW]

It's recorded.  If they played music I enjoyed I wouldn't care so much. But geez that uppity new age celtic music, I can only take so much.  I did go out one night with the HT to see if a little RFI would stir things up but I wasn't lucky.  I think I need more juice.

[KB2WIG]

You need to get back to fundamentals..... like fundamental overload......

What have you in the way of RF generation???                    klc

[W1RKW]

Besides the FT102 and the Viking2 I have a leenyar which I haven't used in years.  I guess I should try it the next time I want to sleep.  I think it would be easier and more prudent to knock on the door. 

[Steve - WB3HUZ]

What was your first rig.... that caused RFI? Can we make this a Sticky?

[W1RKW]

What was your first rig.... that caused RFI? Can we make this a Sticky?

First rig was a PT Cruiser with wobbly wheels

[W2JBL]

that's not water pipe RFI. you have a family of illegal aliens living under your porch, and when you key up you wipe out Telemundo on their pocket TV sets. they are banging on the pipes in protest.