What do you do about appliance QRN?

[K5UJ]

Last night I had a nice QSO with a ham down in Florence AL, and HLR on 3885.  At my place, both had solid signals, but the QSO would have been much less enjoyable, almost unworkable had I not had my MFJ noise cancellation box in use.  This is one of those gadgets that picks up noise with a second antenna (I use the 80 m. vertical if I'm using the dipole to transmit) and then delays it some phase angle so it nulls out.   The local appliance noise here has reached a crescendo in the past few years.  The latest is a popping noise about 10 or 20 times/second that sounds like maybe some kind of circuit charging something.  This thing is 20 dB over S9 but fortunately I can null it out so the noise level drops down to S7, pretty low around here for me (there are other weaker appliance noises under it in the background).  If I didn't have the phase canceling box I'd be unable to operate a lot of the time. 

Am I the only one dealing with this?  I wonder what you guys in town with nearby neighbors do.  Only other thing I can think of is to DF the noise and start talking to neighbors which I have not done yet, but the phase canceling box is only a band-aid and not a permanent solution as these point sources multiply.   I'm starting to feel like knocking on doors is unavoidable but I have a hunch telling someone their new $1000 tv set is a problem for me is going to be an uphill battle.

73

Rob
K5UJ

[WQ9E]

Sounds like DFing time and I would carry some of those clip on ferrite chokes with me.  In many cases they will get rid of most of the noise from appliances by clipping one on the power cord.  The old marine RDF sets sold to boat owners work very well for this task.

Things are still fairly quiet out in the country except someone (and they have to be a mile or more away since those are my closest neighbors) apparently has one of the new ceramic element type heaters since I recognize the noise from one I own.  These are the worst QRM generators I have ever come across and I will track this one down at some point although it isn't too bad.  My normal noise level on 75 is around S-3 and this broadband hash raises it to S-7,8.

Rodger wQ9E

[KF1Z]

Hi Rob,

You say a Pulsing type noise, I'd look for someones electric fence first you did say you live out of town?


73
Jack.

Wouldn't be an electric fence at 10-20 cycles.

[W2PFY]

Wouldn't be an electric fence at 10-20 cycles

Why would an electric fence be at 10-20 cycles?

I need to know

[W3RSW]

My ele. fence is basically quiet (at distance) with intermittant pops from arcing across doubtful insulators unless the wind blows.

Then you hear a discharge for every weed touching the wires, not continuous but can be very annoying.

Don't ever discharge yourself on one 

[KB2WIG]

Some of the batt operated fences 'pulse' the juice to conserve power.

klc

[K5UJ]

Thanks -- I wonder what it is about the ceramic heaters that generates RF noise.  That's just swell--one more thing up here in the winter time.  It's starting to sound like everything that is made and sold that uses electricity puts out RF noise now.

How long before they come up with a way to make flashlights put out noise?  

No, I'm not out in the country Jack, I'm in town so there are no electric fences nearby BUT plenty of other garbage.   There is a website with mp3 files of RF noise you can listen to, to identify sources.  Now that I think about it, the 10 or 20 cps popping noise I hear might be an electric blanket.  I don't recall it being a problem back in the summer.  

Why bring this up here and not on some RFI reflector?  Because noise is especially an issue for AMers.  We operate on HF mostly, have receivers with relatively wide passbands, and deal with relatively lower sideband power thanks to the power limit.   So I figured there would be others here besides me with some experience dealing with RFI.

[KF1Z]

Wouldn't be an electric fence at 10-20 cycles

Why would an electric fence be at 10-20 cycles?

I need to know

Exactly what I said... it WOULDN'T be...
They all pulse, but not at that fast a rate....
Most are at 1cps discharge, some are at 2cps , never seen any faster than that.


How fast does a furnace igniter discharge at?
Are they just 60cps?

[W1RKW]

Wouldn't be an electric fence at 10-20 cycles

Why would an electric fence be at 10-20 cycles?

I need to know

Exactly what I said... it WOULDN'T be...
They all pulse, but not at that fast a rate....
Most are at 1cps discharge, some are at 2cps , never seen any faster than that.


How fast does a furnace igniter discharge at?
Are they just 60cps?

Depends if they are a transformer type or a solid state switching type.  Surprisingly, I have a solid state ignition system on my oil burner and it appear to be RF clean.

I do have a noise as well and naturally it falls in the 75m AM window.  It's a 60cps pulse type noise or buzz which I think is coming from a neighbor.  Also, get noise from what might be their plasma TV at certain times.

[W2PFY]

it WOULDN'T be

Well with no question mark after the statement, I didn't know if it was a suggestion or a question.  But now I know.

[k4kyv]

Have you tried running a battery powered receiver in your shack, and then cutting the main circuit breaker to the house, or pulling the mains switch?  It can be embarrassing to make a public issue about rf noise before finding out that the source is inside your own house.  Worse, after "crying wolf" even one time, the power company and the people next door will be less sympathetic when you try to deal with a noise issue that really may be their fault.

Please explain what is meant by a "ceramic heater".  The ones we have here use resistance wire, wound over a ceramic form.  The ceramic must be made from a material with high specific heat.  The way they work is that the resistance elements heat up the ceramic, which continues to radiate after the thermostat turns the power off to the elements.  That way the ceramic acts as a heat reservoir to maintain a nearly even output, instead of radiating intermittently according to whether the thermostat is on or off.  The ceramic shouldn't have any effect on the electrical operation of the heater or the generation of rf hash.

I suspect you may have some kind of switching supply running the heating elements.  I have a 1500w "quartz" radiant heater for the shack. It's one of those units with coils of fine wire wound inside transparent tubes, and a reflective mirror-like surface to the rear. That way, I can run the main propane heater at about 60° F, with the radiant heater pointed towards the operating position, and maintain adequate comfort.  The heater has a high and low power position and a thermostat.  In the high power position it generates no rf noise, but in the low power position it puts out hash that sounds like line noise.  Since it has a thermostat, I just run it at full power and set the thermostat to a comfortable level.

The demise of AM broadcast radio (and in-house radio listening period) has contributed a lot towards the tendency for nearly anything electric to generate hash.  Back when AM broadcasting was King, the public would not have tolerated consumer junk that spoilt their radio reception.

About a year ago I had a  severe line noise problem, and using a portable radio, traced the origin of the noise to a spot about 2 miles away.  I walked around the area, knocked on a few doors and talked to about a half dozen people.  Not a single one was aware of any noise problem even though they were sitting right under the source and the local 1-KW AM station about 8 miles away was barely audible through the hash.

[Pete, WA2CWA]

Whenever I have pulse type noise, I turn my noise blanker on and it cures the problem.

[WQ9E]

Thanks -- I wonder what it is about the ceramic heaters that generates RF noise.  That's just swell--one more thing up here in the winter time.  It's starting to sound like everything that is made and sold that uses electricity puts out RF noise now.

I think these ceramic heaters are worse than normal appliances because in addition to using an SCR (or Triac) type voltage control for low power the heater element itself is designed with a temperature coefficient so that it avoids getting excessively hot (of course that means its resistance is also constantly changing).  The one I have is OK on the full power position but when run on the low position it puts out so much garbage that not only does it trash the RF spectrum it creates a decidedly different note in the hum of my Desk KW plate transformer (so the heater now sits in a box in the basement).

I discovered the problem with the heater when I was restoring a Gonset G-28 a couple of years ago.  I had finished all necessary recapping and resistor checks and powered it on and it seemed to work OK so I let it warm up for a few minutes before alignment.  I went up for a fresh cup of coffee and when I came back down the audio had the most godawful hum I have ever heard.  I spent some wasted time replacing the rectifier, checking filter caps, and even investigating to see whether half of the transformer secondary had opened.  I finally realized the garbage on the filtered B+ was coming from the AC line and when I went searching I found my wife had turned the heater on and that was the problem.  I presume such devices are not thought of as RF radiators but they provide a nearly DC to daylight spectrum of noise.

Don, I just saw your response and these are known as PTC ceramic heaters.  They are theoretically safer due the the thermostatic action of the element itself and they do work well in some applications (for example the fuel heater in my pickup uses a PTC element) but the combination of that plus the SCR is horrible.


Rodger WQ9E

[KF1Z]

Whenever I have pulse type noise, I turn my noise blanker on and it cures the problem.

Yes, noise blanker on.....
Now that annoying noise is gone, but it always comes at the cost of distorted  audio.... Or at very least, less than full fidelity, nice crisp sound.

The best fix is to locate the source, and get rid of it...

Sure, sometimes that isn't an option.

But, if it's a matter of unplugging an appliance that's hardly every used, or something of that nature, then all the better.

Every once in a while, a new noise source can be an indication that some device is no longer working properly, so tracking it down may serve another benefit.

[DMOD]

Hi UJ, at first I thought you were referring to "appliance" operators.

Appliance QRN can be a real problem at times.

I had a similar problem not too long ago and went around the house with my GE SR and found one offender to be my battery-powered drill battery charger.

Another case in point: Even though we live in a small suburban community, we have quite a few horse farms in the area with electric fences. When I had some spare time, I went around to some of the local horse farms with the GE SR and found one offender that was located about a quarter mile away. I found the owner, told him about my concern with intereference, and offered to help him fix the problem. He was happy with that and we found some bad insulators and loose fence hitting barbed wire, etc. I put some ferrites on the power supply input leads to the chargers and now his farm is QRN quiet.

Also check out local construction. We seem to have new houses going up all around us and occasionally I hear a new interference source. Once construction is finished, no more interference.

Phil -AC0OB

[WB3LEQ]

I have a Magnavox digital TV converter that generates a rhythmical pulse for five seconds, pauses, does a few long bursts, then starts all over again.  I can receive it from 300hzs up through 20 megs.  It sounds similar to something arcing on the utility power pole but it quits whenever I shut it down. In my case it's just the downside of having an indoor receiving antenna. 

[K5UJ]

Hi Phil, Don, and everyone...

BTW Don you were bombing in here the other night on 3885 & I would have called you but I had the rig cooled down to hit the hay...anyway, yes I have done the thing with shutting the service to the house off and putting the rx on a car battery but that was a few years ago so I suppose it wouldn't hurt to do it again. 

One thing that's new and I appreciate being told about it, is my DTV converter box which is plugged in all the time but off but we all know that nowadays if it's plugged in, it ain't really off is it, so I'll have to unplug it and see if that makes any difference.   That's the only new gadget I can think of--fortunately I'm not a big gadget nut--so I'll have to check it out.

Rob
K5UJ

[k4kyv]

Don, I just saw your response and these are known as PTC ceramic heaters.  They are theoretically safer due the the thermostatic action of the element itself and they do work well in some applications (for example the fuel heater in my pickup uses a PTC element) but the combination of that plus the SCR is horrible.

I had never heard of them.  Did a search on the net and found the following.

http://www.specsensors.com/ptc-apps.asp

Looks like the heating element itself is a solid state device. In addition to heating, they might have some useful applications for current or voltage regulation.  I wonder if the noise they generate could be from a negative resistance characteristic that maintains thermal equilibrium, and if a simple rf  filter on the a.c. line that feeds the heater wouldn't do the trick.

Like Rob said, how long before they start making flashlights that generate rf hash!

[KX5JT]

I turned my equipment on just now after returning from town running some errands.  Well, tuned to 3.880 AM and I have a noise level of about s4 with some static crashes no doubt from the cold front that is north of me.  I noticed however from the other room, when I plugged my cell phone into the charger, a loud buzz was heard in my receiver.  Unplugged, dissappeared.  Jeeze!  I'm sure I waded through many QSO's with the thing plugged in and causing me qrn!  Just thought I'd note it here.

[W1RKW]

I had a problem once with my DSL modem wallwart PS. It was noisy as heck, about S9 on the shack equipment and 10over on the bedside receiver. The solution was to shield it in its own metal box with an outlet in the box and attach the metal box to the ground prong on the wall outlet.  Eliminated the noise in the shack and get about an S2 on quiet 75m nights on the bedside receiver. Then took it one step further and put the DSL modem on a programmable timer that operates based on the ham schedule and when the computer is not in use. It eliminates the noise entirely and saves me 22 watts when not in use on the electric bill.

[KC4KFC]

My Dish Network HD TV Satellite receiver generates a popping across the hf spectrum. Could be considered 10-15 hz but is irregular. Loud, popping like a light switch sound. Even when off. It won't go away unless I unplug the stupid thing. It is local though and can't be heard once the receiver is fifty feet or so away from the dish receiver. Once I figured it out, I thought "Geez, don't they care anymore."

Worse culprit I had was a $40 Walmart DVD player that was a gift. S8 hash across HF. I had to find it with a battery radio and keep hitting circuit breakers til I found it.

Good luck.

[WBear2GCR]

popping at some rate can be due to static discharge on the ANT!

dunno if that is what ur getting, but I get it, albeit not at the same rate you mention. One solution for that is the DC grounded ANT.

I am headed that way meeself... DC grounded ANT.

              _-_-bear

[K5UJ]

I tried unplugging all my stuff last night--dvd player, DTV converter, DSL modem...all that stuff and nothing changed so at least I know they aren't my problem.

No, no one cares now.  Here's how it goes:   A bean counter in a suit at some big consumer electronics company looks at a design and thinks, we can get rid of this bleeder cap and that teeny ferrite bead and save twenty cents per unit and it will work fine anyway.  Now, they are gearing up to make 5 million of these things to sell in every Best Buy, Wal-Mart, Amazon and so on all over the world and 20 cents may not seem like much but multiplied by 5 mil. and you are saving a million bucks.  Someone says, won't our product cause RFI?  They estimate the probability of that happening based on estimates of the number of hams and swls there are and conclude the no. of estimated RFI probs. is miniscule compared to the no. of units to be sold so they take a calculated risk figuring the production cost saving is greater than the loss to complainers returning the product for a refund.  The bean counter in the suit wins, gets a big holiday bonus and a pat on the back and the shareholders are happy but joe ham and joe swl get screwed because we don't have the numbers to make a difference.

Thanks Bear for the idea on static discharge.  I have a huge static discharge choke I can put on the vertical here.  It came out of a broadcast tower matching network.  I can maybe make two like it and put them on my balanced feeder lines to bleed them to ground.  May help

Rob