Bizarre things you have experienced with RFI and the like

[darklife]

I know there have been a few threads like this in the past where the topic is about
strange things that have happened with you or someone you know and radio electronics.
The kind of stories where people hear the radio station in their tooth or have random lights
in their house glow because of a nearby radio station.

I'm just curious as to some of the really oddball stories you guys have.
This is part of radio that has always fascinated me. The strange things that happen that even
people with a good understanding of radio electronics and engineering can't explain but have
stories of and seem to agree really happens.

Thanks.

 

[WNTIRadio]

My grandparents lived about 10 miles from WABC, yet it got into EVERYTHING in the house. Phones, radios and even bled into the CB at times!! Never figured out how that happened that far from the TX. One day I need to go back there with the FIM and see what was going on in that location.

 

[satech]

I used to have a Quasar (Panasonic) fax machine which would pick up shortwave radio stations through its handset at night. The strangest thing was, even with the hook switch pushed down, you could still hear it!

Cheap amplified computer speakers are the worst. They have no proper shielding or grounding, so they pick up RFI from anything and everything, especially cell phones.

 

[TomZ]

I detect a detector detected your AM. :

 

[Chuck]

I used to be in the tourng sound buisness. Back in the 1970's we took delivery of a brand new custom built Midas mixing console. It was an amazing 32 inputs, 16 subgroups and four main outputs as well as 6 aux sends. Each channel had parametric EQ, and everything - inputs and outputs - were transformer balanced. For 1976 it was a rocket ship. In fact, it cost about as much as my first home.

It's builder/designer even came along with it for the first 10 days of the tour we were doing, just in case there was a problem. It was flawless, until the day after he left.

We were in Portland Oregon. Upon setting up the PA system, I fired up everything and brought up the master fader. Loud and clear, I got a full fidelity blas tof music from a local AM station. It sounded great, but wasn't exactly what I was expecting.

The guy from Midas was on a red eye plane back to England, so there was nobody to call for help. I tried gounding everything, even wrapping the console in aluminum foil. Still the radio station came in on every channel with remarkable fidelity. I found a pay phone (there were no cell phones back then) and called the station. I spoke with the Chief Engineer who told me their transmitter was about 10 miles from my location and it was only 10,000 watts. Interference because of high signal strength seemed very improbable. Still he was very concerned and drove over to the concert venue ASAP. We both tried every trick we knew, but to no avail.

I finally dragged an older home built console from the truck and substituted it for the Midas. All was quiet.

The next day I set up the Midas in San Fransisco, and it worked perfectly. As soon as I got a chance, I visited an electronics store (yes, they existed back then) and purchased an RF signal generator in hopes that I could duplicate the problem. Running it directly into every input would not duplicate the problem. In fact, I never again had an RF problem with that console. I kept it for well over 10 years and never figured it out, nor did I need to. It is still an RF mystery....

 

[boiseengineer]

Waaay back they got a new BE 4-pot mono board for the news booth. Not a stellar performer but was ok.
News people started complaining about hearing voices in their headphones. Sure enough loud & clear there was "10-4 good buddy" every time a CBer drove by. After much bypassing and the like to no avail we stuck an external amp on the thing and all was well.
They really were an IM distortion, noise, & RF magnet p.o.s..

 

[Schroedingers Cat]

My grandparents lived about 10 miles from WABC, yet it got into EVERYTHING in the house. Phones, radios and even bled into the CB at times!! Never figured out how that happened that far from the TX. One day I need to go back there with the FIM and see what was going on in that location.

My experience is that you only need about 100 mV/m to have things like that happen. That's probably close to what you had 10 miles from WABC. If you get up to about 500 mV/m, things really start to happen. But the longer the thing functioning as an antenna is, the more problems you will have. They manage to have some tuned circuit response, and sometimes different stations are heard on different devices.

 

[WNTIRadio]

One day when I'm passing by I'm going to bring the FIM-22 and see what the signal strength is there for 770. It's a swampy area, so maybe there's some good conductivity running up from Lodi...

 

[rew]

Back in my teenage years I enjoyed playing around on the CB band. I knew enough about electronics to be dangerous and liked to experiment with building linear amps. In those years I lived next door to the local funeral home. They had a cheap pa system all hi Z mics and unbalanced lines. One Sunday afternoon I finished building a new amp and decided to try it out. I didnt know there was a funeral in progress next door. The funeral director said the preacher had just started a prayer by saying "Dear Lord" and then my voice came thru the speakers loud and clear saying "I hear you good buddy" I think a few little old ladies fainted. I always checked to see what was going on next door before I fired up my amp after that happened.

 

[WNTIRadio]

Back in the CB days my grandfather figured out that with the linear on in the car, he could come through the local A&P's PA system. He pulled up one day by the window and said to me, "watch this". Got on the mic and said "Attention A&P shoppers, for the next 5 minutes all bread will be 10 cents a loaf". You should have seen people running from the lines to the bread section!

 

[Chuck]

Waaay back they got a new BE 4-pot mono board for the news booth. Not a stellar performer but was ok.
They really were an IM distortion, noise, & RF magnet p.o.s..

You are right about the P.O.S, board. We have a trailer that is outfitted as a vintage radio studio, complete with turntable, cart machine, reel-to-real tape and other "eye candy." We haul it out to public events and people love the retro look (although the is a computer hidden out of sight). The console is a modified 8 channel BE, but basically the same as yours. I didn't have much trouble with it until I tried firing up a Marti RPU in the trailer. What a mess! RF everywhere....

 

[Schroedingers Cat]

I think the 100 mV/m level has to do with Germanium semiconductor junctions, and the 500 mV/m level has to do with Silicon semiconductor junctions. It has to do with the voltage where diodes and other semiconductor junctions begin to conduct, years ago quoted in Electronics class as 0.2 V for Ge and 0.6 V for Si. It doesn't take much of an antenna to exceed that voltage, like the wire connecting a phone to the phone jack, and the telephone wiring for that matter.

 

[K4WRF]

I was employed for a number of years at a Class A (formerly Class 1-B) 50kW station here that is near the top-end of the dial. The population around the transmitter has become somewhat dense over the decades and there are many stories but one specific instance stands out. Received a call from a gentleman one day who went to great lengths to explain that he was a college educated, local business man (CPA) of long-standing repute and success, not a "nut case". He said that his wife told him he was loosing his mind but late at night when he would go to the bathroom he could hear voices coming out of the toilet. At the time, the station programmed religion at night with a lot of preaching from a fundamentalist standpoint. The man went on and concluded with, "well, go ahead and laugh at me now, because you must think I am crazy". I was able to determine he was with in a couple blocks of the transmitter. I then replied "no, and if he poured about a fourth cup of Draino in to the tank and let it set for a couple hours it would probably stop it from happening."  He was shocked that I was so "matter-of-fact" about it and seemed relieved. A few years later, I received a call from the Tennessean newspaper wanting me to confirm the story as the gentleman had related the seemingly bazaar occurrence to one of their reporters. Soon after, it appeared in a piece about "weird things that I have seen" or something like that. So yes, the toilet copper workings can receive and demodulate radio signals..... The field near his home was right at 1 Volt on the Nelms WX2E meter.

 

[Fieldtech1]

Driving through texas some years back saw the towers lights (top beacon and side markers) of an AM station pulsing/modulated with the music being played on the station. Not sure if it was a RFI or power supply related issue as it seemed i remember the lights dimming to the beat.

 

[Studio1]

In my younger days I had a 200 watt amp on the end of my 26 MHz CB set in the car. Great for DX work and really getting out of bad areas.
Problem was it used to trigger every burglar alarm in town, as I drove down the main street. Most PIRs don't like large amounts of RF at close range.

Somewhat related, I have a Panasonic DMR-EH57 DVD recorder with hard drive on the desk in front of me. I use it mainly for recording the news.
A few weeks ago I noticed it making strange noises, and flashing up the message "Please wait" on a regular basis, even when it was in the OFF mode.
Funny thing was it would only do it sometimes, and a check on Google turned up little of any relevance.
The message would flash up, it would make a weird buzzing noise, then a clunk, then the message again, then silence. Then it would do it all over again.

I finally worked out that sitting my cellphone on the desk right in front of it was the cause. It doesn't like being nuked with 6 watts of pulsed 900 MHz.

Another RF related story goes back to the 70s, when AM was the only service here.
The station I ended up working for (sometime after the event) was noticing that their power was dropping significantly at random times of the day.
The transmitter, tower, coupling and feed lines were all checked. The transmitter was run into a load and performed faultlessly for a week. Put back on air and the problems started again.
Much head-scratching and consternation ensued, until finally it was discovered that a farmer who lived quite close to the mast had built a huge coil inside his roof space, tuned exactly to the AM frequency. He'd charge batteries off the induced voltage and run lights and other appliances from them with an inverter.

 

[ChiefEngineer]

What a cool idea, I think this may have some public benefit. I don't see it draining the power unless it was very within the array.

 

[radionekkid]

we have now wondered past the laws of physics into the realm of bs.

 

[boiseengineer]

Firing up a killowatt on 80 meters will toast most of the old VHS VCRs.

 

[IndigoCoyote]

Unlike most on this board, I am not an engineer- but I have always been fascinated from the production/sales side on what you guys and gals can do. I also have a singing toilet issue. At KUJ Walla Walla WA in the 80s, we'd switch from 5kw non to 5kw directional at sunset. When we did so, this poor farmer's toilet would sing for about 15 minutes or so. He brought the whole station (all 8 of us or so) over one winter afternoon...it actually sounded pretty good. Our engineer wasn't too happy, though. Muttered something about cheap ownership and prehistoric equipment...or something like that.

Anyway, a lot cheaper giving the guy a new toilet that was all PVC inside, than actually fixing the station.

 

[ChiefEngineer]

At WLW there were many stories of lights that would never dim in both the 500kw and current power levels in Mason Ohio. Toilets, bedsprings, and a host of metal items that reradiated music or voice. One account of rectification on fillings was evidence of a loose filling. After fixed, no more WLW. How did that call with the Chief go? "You hear us on your teeth? I have had this happen several times, do you live in Mason? Yes. Call Doc Brown and he will surely have to fix that filling. No. You're not carazy. No. I'm not kidding. Call anytime."
At WGBF we found transmission line problems with a flourescent bulb having no power to it. The line was 6 outer wires (copper) and a single ijner conductor (copper). The old Collins 5 kw had transformers that would sing. Lovely to hear the audio even with no radio. Erwin told me never to walk inside the rf cavity (transmitter energized) with keys in my pocket as the6ywould get hot and I would run screaming out of the cabinet with hot keys. Unless ofcourse I electrocuted myself on the way out.
There is a history of people receiving rf in large amounts on equipment inside their homes with no direct connection. This is hugely inefficient - why we have no wireless power companies.
If I lived near WFNI (50kw) at Zionsville I would consider building something to receive rf and rectify it. Given the rf complaints over the years I would sell a device to people if it had any reasonable means of being useful. So far no such device has been noted and given the broadcasters and engineers generally being cheap I would think such a device would be perfected by now if it existed.