Electrical Interference/EMI all around apartment?

[RedPenguin]

I am trying to diagnose a problem that appears to be electrical interference.

I am in a townhouse like apartment and I have always had fun picking up my county’s channels in the 453-470MHz range.

I finally got my reception almost perfect years ago with a V-Dipole and small dB CATV amp.

Lately though, I seem to be having some sort of EMI.

My scanners, Antenna, and my OTA TV Antenna are all in an upper room as I don't have access to the roof.

Anyway, I noticed lately if I turn an incandescent lamp on/off in the same room or even in the downstairs living room underneath a small fan, it can disrupt reception.

I don't have an extremely easy way to see it on my BCT15/BR330T other than bad audio recordings, but I can see the interference clear as day on the OTA TV equipment. The OTA signal will drop to almost 0% then fix in seconds. It seems to possibly affect regular AM radios also.

I have tried unplugging virtually everything and I can't seem to get rid of this EMI.

I don't know how to prove if it's traveling through the apartment via the electrical wiring or somehow through

 

[tvengr]

Inexpensive CATV amps are notorious for intermod problems. What happens if you eliminate the amp? There may be a transmitter just added in your area creating the problems. Do you have the interference using just the scanner mounted antenna?

 

[RedPenguin]

Inexpensive CATV amps are notorious for intermod problems. What happens if you eliminate the amp? There may be a transmitter just added in your area creating the problems. Do you have the interference using just the scanner mounted antenna?

Yes, I have tried going 100% without the amp on the scanners. I noticed on some of the further away channels, it makes them somewhat worse quality.

Yet, at least for the TV side, Ch 22 (518MHZ) which has an LP station and Ch 35 (596MHZ), just turning on random things like a small nightlight or desk fan, can make mostly the 518MHZ signal go haywire but somewhat the 596MHZ signal also.

I have tried turning off anything that can transmit RF like Bluetooth adapters, WiFi Routers, everything. That doesn't help either.

 

[tvengr]

What happens if you disconnect the scanner from the external antenna and use an antenna mounted on the scanner?

 

[RedPenguin]

What happens if you disconnect the scanner from the external antenna and use an antenna mounted on the scanner?

It seems like the scanner(s) work just fine with the exception of not sounding that great without the V-Dipole on the stations that are like 19 miles away.

It seems like the interference to the OTA Antenna is a little lessened but the TV immediately breaks up.

I also tried a few days ago, the same test with my TV with just a little UHF loop cheap job and that lessed the interference but it was still present.

 

[tvengr]

If the scanners are clean when disconnected from the dipole, that sounds like a problem with your dipole antenna system. What make and model CATV amp are you using? Is it a splitter powered off AC or is it an inline cable amp powered by sending DC up the cable? What happens if you turn off the TV? Is the interference still present?

 

[RedPenguin]

If the scanners are clean when disconnected from the dipole, that sounds like a problem with your dipole antenna system. What make and model CATV amp are you using? Is it a splitter powered off AC or is it an inline cable amp powered by sending DC up the cable? What happens if you turn off the TV? Is the interference still present?

It's an RCA VH140R and it has a 4 splitter built in to it that all powers via AC.

I forgot to mention that the TV Antenna is not actually connected to the Dipole but actually a GE Pro Roof/Attic 29884. I tested an amp with the GE antenna and that intensifies the errors in signal.

 

[RFI-EMI-GUY]

Do you have any LED night lights that have light sensors? A security camera with IR lighting?

"Anyway, I noticed lately if I turn an incandescent lamp on/off in the same room or even in the downstairs living room underneath a small fan, it can disrupt reception."

Do you have any electric heaters plugged in, or in the furnace?

You might have a loose wire in one of your circuit breaker branches. This could be an outlet or switch that was "backstabbed" by the electrician, a lazy cost saving method that makes for overheated and erratic electrical service.

Run an extension cord from a circuit dowstairs to the equipment upstairs. Turn off the upstairs circuits. Try turning off other circuits.

You also might have a burned or loose main service lug on your utility meter or electrical panel. You need an electrician or utility company to tighten those,

 

[RedPenguin]

Do you have any LED night lights that have light sensors? A security camera with IR lighting?

Do you have any electric heaters plugged in, or in the furnace?

No and I also temporarily unplugged my one LED bulb that I did temporarily have it on lamp but that seems to make no difference at all.

No security camera or electric heaters.

It seems that somewhat it's not so much the quick turn on/off that you notice the more interference. It seems you see it more so if you power cycle some electronics a few times with the exception of my Radio Shack NOAA Radio.

Oddly, just plugging the wall wart from the NOAA radio in or unplugging it is enough to drive the signal crazy.

It seems that the scanners for the most part aren't getting the noise anywhere as much as the TV equipment though.

 

[RFI-EMI-GUY]

You might have some loose wires in your outlets. Try to turn off breakers until the noise goes away,

 

[RFI-EMI-GUY]

But get that NOAA radio out of the equation.

 

[RedPenguin]

Well that was some unusual results.

I have an older power strip behind my downstairs TV.

I noticed for a little while now that the red LED is pulsating but I found out online that typically just means the light inside is going bad.

Yet I decided let me flip that power strip entirely off.

I'm not 100% sure yet, but that seems to have at least cleared up like 90% of the interference. Oddly enough, that strip would be directly under the upstairs antennas.

 

[tvengr]

A scanner can emit signals out of the antenna jack and into the antenna jack of another scanner when connected together by a splitter. They can interfere with each other. Your splitter may not have good isolation between outputs. I use a Stridsberg Engineering MCA204M multicoupler for feeding my scanners from a common antenna. I would also check that the TV, scanners, and amp are all fed from the same AC outlet. You can have ground loop problems when AC is fed from different locations. Any time you connect electronic equipment together, you can have ground loop problems. TV's can radiate signals and interfere with each other also.

 

[RedPenguin]

Well on pure accident, I seem to have figured out a major cause of the interference.

It did it again after I changed to another power strip.

Strangely, it seems like it's actually a dual USB charger that seems to be causing the issue.

Even though the dual USB charger is plugged in downstairs in the living room, if you have it plugged in, equipment upstairs seems to cause interference.

Yet if you unplug the USB charger, then strangely electronics upstairs don't seem to create the interference. Even the NOAA radio won't have it show up.

EDIT: I take that back about the NOAA radio. That still seems to cause it but without the NOAA (upstairs) or USB charger (downstairs), it seems the night light no longer at all makes any interference.

 

[tvengr]

I remember seeing another report of USB charge outputs causing interference problems. I'll have to remember that one for future reference..

 

[slicerwizard]

USB chargers have disgusting SMPS circuits.

 

[RedPenguin]

I still seem to be getting video errors on the TV Ch 22.

I was told on another forum that it could actually be the channel itself (owned by HC2) but it's a channel that has only been on the air since Feb.

I have nobody locally that can run tests for me though to see if they get the same issue.

It does seem though that the electrical interference is gone at the very least though, as nobody how many times I turn lights off/on, that doesn't break up the signal of Ch 22 or Ch 35.

I wish there was some simple way to prove my end or the transmitters end. I am only 2.21 miles away.

 

[vagrant]

USB charger, yes indeed can cause massive RFI. I discovered that while near 9000’ in the Sierra National Forest, miles away from anyone. I cannot say all of them do that, but once contained in the metal of a Sterno stove, it was dramatically reduced. The RFI was on HF, VHF, UHF. I did not check higher or lower than that. Wall warts can also be an issue.

As to your channel 22 problem, is an FM radio station nearby? Have you tried an FM filter inline with your OTA antenna? If you have a station nearby and it is around 104 MHz, definitely try the FM filter.

 

[RedPenguin]

USB charger, yes indeed can cause massive RFI. I discovered that while near 9000’ in the Sierra National Forest, miles away from anyone. I cannot say all of them do that, but once contained in the metal of a Sterno stove, it was dramatically reduced. The RFI was on HF, VHF, UHF. I did not check higher or lower than that. Wall warts can also be an issue.

As to your channel 22 problem, is an FM radio station nearby? Have you tried an FM filter inline with your OTA antenna? If you have a station nearby and it is around 104 MHz, definitely try the FM filter.

I actually have a bunch of FM stations nearby unfortunately. They actually put at least 2 right in between Ch 22 & Ch 35's towers.

I put on an old Radio Shack FM Trap that I had and at first I thought it was actually working.

Eventually though, errors again.

I know my area does seem to be swamped with FM though as I remember years ago, you could oddly find FM stations I think all the way up on 200MHZ+. I think I even found interference at least 300-500MHZ occassionally.

EDIT: FM Trap to Amp seems better but not perfect

 

[jonwienke]

Get a SDR dongle and a USB extension cable, and put a rubber duck on the dongle. Plug it in to a laptop running SDR# and use the SDR like a metal detector to hunt the RFI.