Is this normal?

[K4EET]

Do you have any dimmer switches on the lights? Anything with a remote control to turn it on/off? Just trying to think of what might still be energized.

Excellent example of another something that can become active again when a circuit is switched back on with individual switches all turned off.

 

[SpaceForceCmdr]

I do have a dimmer on the dining room light, which is on that circuit, but it's one of those with a knob that rotates. You have to first press it in to turn on the light, then rotate to dim/brighten. Coincidentally, that room does seem to be where I get a really strong hum on my portable. Could this be energized even when clicked off?

As for the wall warts, I think I've eliminated them as the causes. Unplugging them seemed to make no difference, but if all else fails, and can double check. It was getting pretty late last night.

 

[majoco]

Could this be energized even when clicked off? - most definitely!

 

[SpaceForceCmdr]

Wonderful =) Would all dimmers be like this? I guess the only way to know if this one is causing the trouble is to disconnect it from the wiring, that way I know it's not getting any juice?

 

[SpaceForceCmdr]

Here's another interesting thing: I just took off the plate for the dimmer, and the ground wire (green) is not connected to anything? Would that be an issue?

 

[SpaceForceCmdr]

ANOTHER UPDATE: So, this is really interesting. I cut the power (using the breaker) to that dimmer in my dining room. The lights that it controls go out. Here's where things get weird. If I push the knob in on the dimmer (to turn it on), the low humming starts when I'm tuned in to 4840 (and probably other freqs, too). If I press it again, the humming stops. The thing is, there shouldn't be any power going to that switch because the breaker is tripped. WTH??

 

[K4EET]

Here's another interesting thing: I just took off the plate for the dimmer, and the ground wire (green) is not connected to anything? Would that be an issue?

Possibly but not necessarily if it is getting a good ground from the metal frame to a grounded metal electrical box. If the electrical box is not conductive material, then the green wire needs to be connected to the ground wire of the electrical cable.

ANOTHER UPDATE: So, this is really interesting. I cut the power (using the breaker) to that dimmer in my dining room. The lights that it controls go out. Here's where things get weird. If I push the knob in on the dimmer (to turn it on), the low humming starts when I'm tuned in to 4840 (and probably other freqs, too). If I press it again, the humming stops. The thing is, there shouldn't be any power going to that switch because the breaker is tripped. WTH??

Strange indeed but I have come across things more complex in the weird department before. It's late and I'm tired. I'll come back tomorrow and hopefully somebody will have given a better answer than I could have given.

 

[SpaceForceCmdr]

Just to be safe, I attached the green wire from the switch to the inside of the metal elec box. My house is from the 30s, and there were only 2 wires coming into that box (no ground). When I tuned in later, it made no difference in "The Hummer" (that's what I decided to call my "broadcast, haha").

I'm just glad this weird RFI doesn't seem to be causing me issues in the ham bands. I will typically get some fading and weak signals there, but no annoying hum. I was able to pick up a dude from Russia last night, so I am pretty happy with my receiving ability.

 

[KE5MC]

...snip...
The thing is, there shouldn't be any power going to that switch because the breaker is tripped. WTH??

One house I lived in I was updating switches and outlet. The hallway light had two-way switches at each end. Some dummy wired the circuit connected to two different breaker branches. I identified one breaker and turned it off. Got a slight buzz or maybe I meter checked I don't recall, but had to turn a 2nd one off. I never did sort that problem out. Functional it worked, but was not right.

House wiring can be a nightmare to figure out. My current home I updated switches and outlets again. I took the time to map the breaker panel and created a detailed list of what each breaker powered. It was worth the effort to eliminate the poor back wiring connections and things I found. I can't say my house has lower RFI, but at least I know the connectivity.

Seems like you are getting a handle on things.
Good Luck!
Mike

 

[SpaceForceCmdr]

Now that you mention it, I have to check this out. There are two switches on the first floor, and two switches on the second floor, and I think they are wired to the same lights. I can turn on the upstairs lights from downstairs or upstairs. Not sure if they are on the same breaker, though.

 

[SpaceForceCmdr]

Do you guys happen to know why I'd hear this awful, low humming interference on AM signals, but not SSB? I was tuning around the 7 Mhz range, and on AM broadcast it was awful, but if I tuned into hams around the same freq on SSB, there's zero hum. Not that I'm complaining, but just wondering if that's typical?

 

[SpaceForceCmdr]

To try to mitigate the noise, I was playing around with my loop antennas. I have a Youloop and also the active MLA-30+. Neither of these seem to make much difference indoors. I think the low hum may be slightly better, but I can still hear it. The MLA-30 works almost as well as my long, indoor wire at pulling in most signals, but it also boosts the noise floor, so I think it's inferior. The noise floor is lower on the Youloop, but it's signal is also a lot weaker.

I put the MLA-30 in my backyard just slightly away from the house, and that does seem to almost eliminate the nasty, humming sound.

 

[Boombox]

Do you guys happen to know why I'd hear this awful, low humming interference on AM signals, but not SSB? I was tuning around the 7 Mhz range, and on AM broadcast it was awful, but if I tuned into hams around the same freq on SSB, there's zero hum. Not that I'm complaining, but just wondering if that's typical?

SSB sometimes 'covers up' noise. I've never seen it cover up really bad hash, but when there was powerline noise around here it would sound horrible on AM mode but SSB would sort of cover it up. Can't explain why. It might be due to most SSB reception being in narrower mode -- you're mainly tuning to one sideband. It also may be due to the carrier that the radio is injecting to decode the SSB covers up some of the noise.

Others here who know better will probably have a better explanation.

 

[SpaceForceCmdr]

OK, so I believe the low, pulsing hum is not actually interference from my home or electrical system. It's my PC! I discovered that if I tune into 4840 right now, even though there's not detectable broadcast, I hear the hum. Now, I if connect the SDR to my laptop, but use the same, there's static, but the hum is gone. Now I just need to figure out if it's possible to connect the SDR to my while somehow removing the interference. I'm going to start a new thread in the SDR section if anyone had advice. Thanks!

Help with RFI coming from my PC please!

I've been getting a low, pulsing hum on certain stations (happens a lot around 4840 and the surrounding areas). I was pulling my hair out, but I think I figured it out. It's not interference from my home electrical system or various electronics: it's my dang PC! I connected my SDR (HF+...

forums.radioreference.com

 

[SpaceForceCmdr]

Looking at this further, there is definitely some noise coming from my PC, but it's not what's causing the hum on 4840. Using the circuit breaker method, I think it has something to do with the light switches. I did remove the dimmer in my dining room just to see what would happen with it disconnected, but it didn't resolve the issue. There is still some weirdness going on because even with the breaker off, if I turn on the light switch in my computer/radio room, the hum returns. Not sure why as there should be no power going through the switch.

With the power on, and the switch on, the hum seems to increase. I currently have 2 LED bulbs in the overhead fixture, so that may be causing some of it. Not sure what to do since I need light in the room. I had a spare bulb that another brand, and I put that in, but same thing. Still not 100% sure the LEDs are the only thing causing the hum, but they definitely seem to be contributing.

Is there a type of bulb that's known for not causing RFI? I could try to go back to incandescent, but not even sure those are available anymore.

 

[SpaceForceCmdr]

SSB sometimes 'covers up' noise. I've never seen it cover up really bad hash, but when there was powerline noise around here it would sound horrible on AM mode but SSB would sort of cover it up. Can't explain why. It might be due to most SSB reception being in narrower mode -- you're mainly tuning to one sideband. It also may be due to the carrier that the radio is injecting to decode the SSB covers up some of the noise.

Others here who know better will probably have a better explanation.

Well, I'm definitely glad for this since SSB is my main interest. TBH, most of the SW broadcast stuff is talk radio in another language, or religious stuff, and I'm not very interested in either. It is kind of cool to hear foreign music, though.

 

[wtp]

a found a house down here from the 50's.
the house wiring does not have a true ground.
an electrician used a what is called a floating ground (common ground) but still not grounded.
that just means that he put in 3 hole outlets all around the house and just tied all of the grounds together.
could this be a possibility ? it sounds it to me.
also the satellite guy got a good shock because he grounded his cable and then got in between the box and the cable.
the cable was grounded on the incoming wire and the box is tied to the rest of the stuff in the house.
it has since been corrected.

 

[SpaceForceCmdr]

Help with RFI coming from my PC please!

I've been getting a low, pulsing hum on certain stations (happens a lot around 4840 and the surrounding areas). I was pulling my hair out, but I think I figured it out. It's not interference from my home electrical system or various electronics: it's my dang PC! I connected my SDR (HF+...

forums.radioreference.com

 

[littona]

With the power on, and the switch on, the hum seems to increase. I currently have 2 LED bulbs in the overhead fixture, so that may be causing some of it. Not sure what to do since I need light in the room. I had a spare bulb that another brand, and I put that in, but same thing. Still not 100% sure the LEDs are the only thing causing the hum, but they definitely seem to be contributing.

Is there a type of bulb that's known for not causing RFI? I could try to go back to incandescent, but not even sure those are available anymore.

LED lighting can definitely cause RFI. The only thing you can really do is try changing brands, unless someone knows of a web site somewhere that has analyzed RFI from different manufacturers. The bottom line is that the cheaper brands don't really care about RFI.

 

[wtp]

2 wires is what i was talking about.
without a real ground you get to pick up everything as the 3rd wire is now an antenna to every outlet in the house.
it might be time for a real electrician anyway.