The AM Forum

A ham friend of mine had been complaining about a high line noise of S-7 on 75 meters for a while.  He presumed the problem was sourced from the power company's lines at his spacious country property.

I visited his house with a TS-820 transceiver that I had run at my QTH on 75 so I knew what should be the normal QRN and noise level on that TS-820 which also had a good operating noise blanker. 

I brought along my Sony ICF-2010 portable short-wave receiver for tracking the noise also.  As I drove to the QTH I was listening on my car's AM radio.  My opinion after walking around the property was that there was no strong line noise from the utility lines and that the source is probably in his house.  The dipole is positioned right over the roof of the house so this is a noise-critical situation for receiving on 75.

My TS-820 read S-7 also confirming the problem.  My noise blanker would not reduce the interference.  So we turned off breakers one by one, listening on my 2010 and found 2 breakers that reduced the noise and when both were off the interference was completely gone.  The one source has not been found and that breaker remains off, apparently some obscure load and outlet that could not be spotted while I was there.

The other breaker was for a living room and I unplugged appliances there one by one.  The offending appliance in that room was a Toshiba DVD player.  The player was off but as long as it was plugged in, it was generating the S-7 level of white noise, almost no 120 Hertz buzz to it at all.  So since the player is hardly used it remains unplugged until needed.

During my initial walk of the property I noted that a cable TV feed from the house to a barn apartment was hot with noise.  Later I believe I found the explanation for this; an ac line surge arrestor block in the room next to the living room.  There is a TV in this room and on the wall outlet behind the TV was this 9 - 12 ? outlet block and the cable TV service snaked through two F connectors at the bottom of  the block.  I believe that this arrestor coupled the line noise onto the cable TV cables at this point.  Disconnecting the TV cable from the block reduced the received noise level and once the DVD player was disconnected the arrestor block connections were restored to provide the supposed lightning protection to that TV.

After the DVD player was pulled, the QRN level was S-2 to S-3 maximum; the proper level for a QTH with no noise interference.

This interference was put up with for a very long time assuming that the source of it was the power company’s responsibility.  So obviously the thing to do is to get a battery-operated receiver (can be a solid-state HF transceiver with a battery) going and kill the power to your QTH and confirm whether the noise is from your house or before your breakers and proceed from there.

That is why I put up my ladder line fed doublet 160 ft away from the house.    I had RFI from different things in the house that it was not practical to shut off.    Moving the antenna away fixed up most of RFI.   One strong bugger was a cell phone charger that had to be unplugged whenever the ham rig was in use however.   A new cell phone contract and new phone fixed that up.

Just today also a ham friend of mine said he had found that a Ryobi cordless drill charger gave him RFI. 

Apparently all of these various chargers people leave plugged in today are becoming a significant source of wasted energy.

Yep, it's not always the power company. Sometimes the obvious is obviously wrong... ;D


I once had a 10M rotary Yagi mounted on a tower right above the house at about 50'.  It picked up all kinds of tones coming out of the computer. The path from the computer through the house floors and roof was all wood, so the RFI propagated well.

After relocating the Yagi about 200' from the house, everything was quiet. That computer noise seemed to really pick up on the higher bands, especially on 6M, so be aware of this when planning antenna locations for the sunspot years to come. 

T

I'll vouch for that as well.  I have an 18V NiMh set (4 piece + charger).  It's S7+ from 80-10 meters.  Pick it up on my Yeasu, a Cobra CB radio, and a little shortwave set (handheld Radio Shack unit, silver in color, not here, so I can't give the model number).

As do the "electronic" ballasts guys use for the MH and HPS lighting.

Cell phone chargers and drill chargers are all becoming switch mode power supplies.  It's cheaper!

--Shane

Don't you just love all that consumer junk that stays on even when the switch is turned "off"?  No telling how many fires this causes per year, plus all the wasted energy, carbon emissions, etc, not to mention unnecessary RFI.

No discussion on the horizon about curtailing those things, but they still want to take incandescent lamps off the market.

If you read the Sonny Irons story (http://www.browardpalmbeach.com/1998-04-23/news/sonny-s-last-stand/1), you will see the part where the cops raided his house, with code enforcers close at hand.  Perhaps understandably, they were  trying to "get" the guy any way they could, so the code enforcer cited him for using an extension cord that wasn't UL approved.

Some years back after subscribing to Dish Network, I had a similar, annoying and persistent sound appear in the receivers some 40-50 feet away at the other end of the house. Using the same method of shutting stuff off but from the source rather than the breaker box (saved a lot of trips up and down the cellar stairs), I was able to isolate it to the Dish receiver. After that I added an outlet strip that could be switched off as needed. Only problem was, each time I did that the receiver had to reboot. The current DVR hasn't proven to be a problem (yet), but it has the same reboot issue when power is lost.

Never could figure how much of it was traveling through the line vs airborne, though. Should've tried some of those clip-on ferrite beads.

Yep. I posted about this exact same thing.   In my case it was a philips HD DVD player. It was OFF.  It produced S7 to S9 on my RXer all the time.  My Sony like yours found it.  I put the Home theater rack on a power strip and just turned it off. If we want to use it, We turn it on... Cant talk on the radio and watch a DVD at the same time anyways!

other sources at my house are Air purifiers, Florescent lights in kitchen, and the big one.. The neighbors Pool pump..

Clark

Yup, we are all at the mercy of whatever our neighbors decide to buy off the shelves at Walmart. The little 5 volt switching supply that came with my D-Link router was nasty on HF. It had little warbling oscillations spaced every 60 kc that slowly traveled up the band. Easy to watch what was happening on the spectrum display of the Pro III. Easy to fix too, just replaced it with a linear supply. Too bad Part 15 appears to be insufficient to stop the proliferation of these noisemakers.

Build a dedicated antenna to pick up the noise, amplify it, and  pump it back into the TV cable system.  That'll bring in a few complaints.

Tom

I had EXACTLY the same problem here and solved it the same way.  The noise had a sort of cyclic machine noise and turned out to be a piece of crap Phillips DVD player.  It has since found a home in the circular storage facility.

I thought we had RFI radiation specifications -- apparently they are toothless

Al

I wonder if I am the only one who is somewhat outraged at the FCC busting Hobby Lobby (a chain or craft and hobby retail stores) for violating some part of Part 15 because they imported these nifty little gadgets from Australia and sold around 100 of them?  I read about this on the ARRL news website.   Some VK company makes this teeny tv camera and 10 mW tv transmitter that's powered by a dime battery.  It's lightweight enough to be a payload on a RC model airplane.  You also get these LCD goggles to wear that connect to a receiver.  You put the camera and tx on your airplane positioning it so it looks forward.  Once you get airborne you are supposed to be able to put on the goggles and it's like your a tiny pilot on the airplane.   Is that cool or what?  BUT they violated some technicality and FCC smacked them down, ooo rah. 

Now, this was a no no, but the importation of _millions_ of crap power supplies that are destroying HF .... that's perfectly okay I guess, at least I have read _nothing_ about FCC enforcing any RF suppression with these supplies. 

At my place my low band noise level is typically S9.  Sometimes it gets down to S7 (wheee hooo).  And there's always some junk fired up around me (I've done the battery receiver trick and found some dimmer lamps and turn them off when I operate the station) and I know it's from outside.  I can work you if you're running a Viking or more but Rangers and AF67s and such are tough.

73

Rob K5UJ

I have a little phase cancellation box that sometimes nulls out noise but if ham radio ever dies it's gg to be death by a 1000 cuts--antenna restrictions, noise from consumer junk, kids' lack of interest, BPL...

Don't even get me started on touch lamps and touch switches.  The big box stores like Lowe's and Home Cheapo are loaded with them, and not a damn one has the required Part 15 warning label about rf interference.  They even make wall switches with a solid brass plate so all you have to do is touch the switch plate to turn on the light.

Imagine if the people next door equip their entire house with the damned things!  What I can't imagine is someone too damned lazy to turn a knob, push a button or flip a toggle switch to turn on a light.

One consolation is that a nearby transmitter, even at low power, will often make the things go crazy and the lights will blink on and off randomly while the tx is keyed down.

The time my daughter brought one home, it lasted for 2 days before I found out what was wiping out my reception.  I bought a regular switch, yanked out the touch switch module, drilled a hole in the brass base of the lamp and mounted the manual switch.  I told her she could stay, but that touch lamp had to go.

Besides, they are a safety hazard.  What happens if you are standing barefooted on the concrete floor in the basement, and you reach up to turn on the light, unaware that a component in the touch module has shorted out?

What sticks in my craw is driving up in the 'vicinity' of a traffic light and having your FM station wiped out by the clock in the light's PLC. I never measured the output but I always though you weren't supposed to detect anything like that from more than 15'. (?)

When the LED traffic lights first appeared here in NH, they were really CRAPPY with noise.  I'm not noticing that problem so much.  Wonder if anyone knows if the FEDS stepped in and regulated that noise away.  Seems to me it might be a emergency vehicle problem if they miss an important comm.. because they were passing under or going around one of these NOISE GENERATORS.

Al

Hi Tom,

Was this Bill DGB? Worked him last weekend on the AWA net and he mentioned the exact same story.

It amazes me how this stuff is allowed to "pollute" the RF spectrum, I used to think that was what Part 15 was all about, but as one of the fellows pointed out, Wal-Mart's China junk hardly qualifies as a being tested.
Thankfully I'm a long way from any neighbors with that junk.

Not sure if it was your efforts, but Bill's signal on last weeks net was the best I ever heard him.
Wondered if you guys raised up the antenna?

I know of a case where a disgruntled cable TV customer injected a swept oscillator back into the cable at some +20dBm. This went on for several days until a cable TV van appeared on his street. He shut it off before he got found out.

In another case, a person was fond of injecting home videos right on channel 3 into the cable at whatever hotel he was staying at. That was before the days when the TV sets were all programmed and locked down. Back then the rooms had a set top cable box like tuner with a manual slider on them.

Today, I am not sure feeding anything back into the cable would work well because they have amplifiers along the line. I suppose they are one-way. ?

We all know of the FCC certification for the cheap equipment. So, what is the responsibility, where does it fall, when you have proven that your Toshiba DVD player is making hash?
What remedy is the available to the person who bought the equipment?
I suppose if I knowingly buy the equipment then it is my problem?

My burglar alarm is a huge noisemaker at 3-4MHz. I may have to try bypassing the leads to all the doors and to the keypad. Oh, hehe what happens when you have a keypad with a noisy clock and scan running through cheap wire to the "brain"?

I can't use that 3-4MHz band in the house, but out in the lab there does not seem to be an issue. However, the upcoming dipole will extend right over the house.

I have posted on some of these I found before at my house.

iRobot Roomba switching charger - very bad broadband noise
Gas dryer with electronic controls- very bad noise, particularly on 40
W&W Associates HT pack charger - pretty bad considering it's sold to hams.
Diamond 40A variable 12V supply - throws drifting birdies on HF (sold as ham radio supply)
Chinese cellphone charger for Treo 650 - light noise mostly while charging (goes away when Treo fully charged)

Cable companies that have internet service have to be two-way, in fact if you have a cable modem and put in a preamp, you have to be sure it is two-way.   I don't know the backwards bandwidth and whether you could send some TV channel video back.

You'd think with the FCC having to raise much of its own funds that this sort of stuff would be a gold mine with all the fines they could issue.  Then they could back off on the spectrum auctions.

Scott Todd

From the ARRL Letter, VOL 28, NO 30 (FRIDAY, JULY 31, 2009)

==> FCC ISSUES CITATION TO PART 15 MARKETER

On July 28, the FCC issued a Citation to Hobby Lobby International (HLI)
<http://www.hobby-lobby.com/> for marketing non-compliant radio
frequency devices

<http://hraunfoss.fcc.gov/edocs_public/attachmatch/DA-09-1626A1.pdf>.

According to the Commission, these devices were in violation of the
Communications Act of 1934, As Amended and the Commission's Rules, as
well as United States Customs and Border Patrol regulations.

On March 5, the Spectrum Enforcement Division of the Commission's
Enforcement Bureau sent HLI a Letter of Inquiry, initiating an
investigation. The FCC wanted to know if the Tennessee-based company was
marketing an unauthorized radio frequency device, specifically, the
Pilot View FPV 2400 video transmitter

<http://www.rcgroups.com/forums/showthread.php?t=858566>.

According to the Citation, the FCC observed that the device was marketed on the
retailer's Web site.

HLI responded to the Letter of Inquiry on May 7, telling the FCC that
they began selling the Pilot View FPV 2400 video transmitter on May 12,
2008; they have sold 109 units of the device in the United States. In
its reply, the company told the FCC that the manufacturer of the
transmitter, Intelligent Flight, an Australian company, represented to
them that the device was FCC compliant. HLI admitted they imported the
transmitters, but did not file any FCC Form 740s for the imported units
(before radio frequency devices may be imported to the United States, an
FCC Form 740 [or the electronic equivalent] must be filed with the
United States Customs and Border Patrol). According to the Citation, HLI
stated that the last date that a transmitter was received was November
17, 2008, which is around the time that HLI's contact at Intelligent
Flight stopped responding to their requests for further information
concerning the device.

The FCC noted that HLI sent a unit to a test lab prior to receiving the
Letter of Inquiry. "After receiving the Letter of Inquiry, HLI contacted
the test lab to inquire about the test results and learned, for the
first time, that the device is not FCC compliant," the Citation said.
"HLI provide[d] a copy of the test results, which indicate that the
device substantially exceeds FCC radiated emission limits. HLI state[d]
that [they] discontinued selling this device as soon as it became aware
that the device was not FCC compliant."

The FCC said "it appears that HLI violated Section 302(b) of the Act and
Sections 2.803 and 15.209 of the Rules by marketing in the United States
the Pilot View FPV 2400 transmitter. It also appears that HLI violated
Section 2.1203 of the Rules by importing the Pilot View FPV 2400
transmitter without making the required import declaration."

HLI was warned that "if, after receipt of this citation, you violate the
Communications Act or the Commission's Rules in any manner described
herein, the Commission may impose monetary forfeitures not to exceed
$16,000 for each such violation or each day of a continuing violation."
The company was given 30 days to respond to the Citation either through
a personal interview at the Commission's Field Office nearest to your
place of business or a written statement. HLI was advised that any
response should specify the actions that they are taking to ensure that
they do not violate the Commission's Rules governing the marketing and
importing of radio frequency equipment in the future.

Take a look at this FCC page for an almost endless list of equipment enforcements:

http://www.fcc.gov/eb/marketing/

Interesting information Steve and Tom. I read some of the citations and it appears that the F.A.A. was the complainant in a few of those. I would imagine they can get the attention of the F.C.C. pretty quickly. Still, it's awkward for a ham to show up at the doorstep of a neighbor's house with his/her geeky equipment complaining or inquiring about possible sources of RFI. Of course if your neighbor is not interested in speaking with you about it, you are SOL. As far as I know, there is no enforcement body that will be coming out to assist you with this crap. I suppose the F.C.C. might send a letter if you document the problem with enough intensity, but I doubt there is much hope for resolution with an uncooperative neighbor. Somewhere the inspection and approval process is broken and the end result of that is more and more noise.

I listen to the AM broadcast band in the car at times and find that even in my little rural town the amount of noise along some stretches on the main road is incredible. It's not just the usual powerline noise either, in some places DSL data noise and U-Verse leakage is roaring away on top of all kinds of weird appliance noises and electric fences. It must be frustrating for those who operate HF mobile!

Good thing the gummint division that takes care of LASERs is not so vigorous. Due maybe to FAA complaints and run of the mill evildoers, they are, however, banning imports of some lasers, broadly speaking mostly those that:

emit more than a certain amount of power and do not have the proper safety devices integrated
-or-
emit more than a certain amount of power and are not OEM devices designed to be integrated into a system.

Both need to be licensed in the state of TX though. $350 each laser.. There is a loop hole. If the power can be controlled by a setting to some lower amount, I forget hwat, no license is needed unless the device is operated above the limit.

So for now, anything that looks like a >5mW pointer or "mega pointer" is being forbidden. Barebones parts and assemblies are not. I just ordered two 100mW red laser OEM assy. Yet a deviation in the enforcement is that the green one that seems exactly the same OEM type and form factor is forbidden.

I need the red lasers to align the optics on a YAG laser project. Red will pass through.. green generally does not. Nonetheless, why the clampdown on the green lasers? same box. what gives?

Someone is always out to spoil the experimenters' efforts.

(AM content- -these can be amplitude modulated and operate on 461 or 565 THz, respectively. Yag as an aside is pulsed operation at 282 THz. )

Thank goodness there are no LASER Police. Yet. An eventual goal is the retroreflector on old Luna. Not hard getting the pulse there. Hard is listening (looking?) for the return buried in the noise. others have done it and it is generally not as easy as with radio waves. So alot of people don't try it. besides it has little practical use except to impress girls.