Clients Ham Radio noise issue.

[AC\DC]

friend and client is a Ham Radio operator, He is getting Noise between 17kc-4mhz its silent at 7mhz so its below that range.
It started 2 months ago, he has found that it goes away when he turns off the M. Bed circuit breaker. He unplugged everything and got disconnect the line side of the GFCI to make sure nothing was on it.
WIth nothing plugged in it and when he throws the circuit, the noise slowly ramps up.
I don't know alot about this subject, I though maybe a Neutral to ground would cause the noise. He is in a manufactured home so its is on chassis.
He is a retired EE.

Any help or ideas.

I think I going to disconnect the mid point to narrow it down and go from there, but would like to know if there a better way to trouble then the typical way.

 

[tthh]

Any new things in the MBR circuit? Dimmers and light bulbs come to mind.

 

[N6CO]

There is no dimmer etc in the master , everything was unplugged from wall -
The noise is coming from the house as I have the ham radio hooked to a
solor battery and with master bedroom breaker turned off - noise goes away
Have changed the breaker for GP and still the same , big problem, I do not
have that much hair to pull out these days ( this one has me stumped

 

[synchro]

You might want to verify that no receptacles in other rooms go dead when the breaker for the master bedroom is turned off.
A clamp meter could be put on the output of the breaker with everything unplugged in the master bedroom to verify that there's no measurable current.
I would be suspicious of any "wall wart" power supplies or cell phone chargers.

 

[tthh]

If it is doable, what I've done more than once is divide and conquer. You need map out the wiring as best as possible and start disconnecting segments until it goes away. Then you can narrow the problem. How do you eat an elephant? One bite at a time.

 

[AC\DC]

That what I was going to do. The amp clamp is a good idea to make sure no small loads are on.

 

[synchro]

If you have a battery operated AM radio (not as easy to find these days) you could move it around to see if the noise is stronger ar any particular location. With the breaker off, I would set the frequency where there is no station present (or at least no strong station).

 

[N6CO]

Found my camp on amp meter and with breaker on shows zero amp's , nothing
on in the master bedroom at this time.
neutral is 3 amps - this seems about right for the umballaced current.
I assume
I also found my VERY old walkman that has a AM radio in - but it does not work -
I also have/had a emergency radio that has AM - so back to looking in box's.
We moved here not to long ago and still trying to clear out box's

Sub note - all was quiet until 1 month ago and what has me baffled is the
ramping of the noise - from a S-4 up to a S-9 in 10 min's with nothing on and everything unplugged - I am going to find the Em am radio and make sure there
is nothing happening with one of the wall outlets -- five hairs left ((

​

 

[LarryFine]

Found my camp on amp meter and with breaker on shows zero amp's , nothing
on in the master bedroom at this time.
neutral is 3 amps - this seems about right for the umballaced current.
I assume
I also found my VERY old walkman that has a AM radio in - but it does not work -
I also have/had a emergency radio that has AM - so back to looking in box's.
We moved here not to long ago and still trying to clear out box's

Sub note - all was quiet until 1 month ago and what has me baffled is the
ramping of the noise - from a S-4 up to a S-9 in 10 min's with nothing on and everything unplugged - I am going to find the Em am radio and make sure there
is nothing happening with one of the wall outlets -- five hairs left ((

​

Tune the AM radio to a quite spot near the low-frequency end of the band.

 

[synchro]

Found my camp on amp meter and with breaker on shows zero amp's , nothing
on in the master bedroom at this time.
neutral is 3 amps - this seems about right for the umballaced current.

So does this mean it's a 3-wire multi-wire branch circuit, where the master bedroom circuit is sharing a common neutral wire with another circuit powered by a different breaker? If so, try turning off that other breaker to see if it has any effect.

Sub note - all was quiet until 1 month ago and what has me baffled is the
ramping of the noise - from a S-4 up to a S-9 in 10 min's with nothing on and everything unplugged - I am going to find the Em am radio and make sure there
is nothing happening with one of the wall outlets -- five hairs left ((

Do any of the wall outlets have USB charging ports?

 

[zbang]

A ham operator should be able to make a directional antenna. Even connecting that with a suitably-long lead to a table-top radio should help find the noise source.
I'd also turn off a lot more breakers to see if the problem changes.

 

[Speedskater]

What about a:
1) old doorbell transformer, arching when it gets hot.
2) bad CFL bulb, that is thought to be switched off.

 

[BarryO]

AFCI breakers have microcontrollers in them; a sensitive Ham receiver may detect the RFI that they generate.

 

[hbiss]

AFCI breakers have microcontrollers in them; a sensitive Ham receiver may detect the RFI that they generate.

He doesn't have any AFCI breakers.

However,

We just discussed in another thread how GFCI receptacles that self test generate an RF signal to detect a neutral to ground fault with the wiring connected to it.

-Hal

 

[drcampbell]

A ham operator should be able to make a directional antenna. ...

The wavelength of a 4 MHz signal is 75 meters; at 17 kHz it's 18 kilometers. A directional antenna might be a trifle too big to use in a house.

I suspect a parallel arcing fault.

 

[synchro]

What does the noise sound like when receiving in SSB or AM modes? For example, is it a continuous rushing noise, or a buzzing noise possibly at a 60 or 120Hz rate?
That might help provide a clue about what is happening.

 

[N6CO]

Breaker off and other breaker on

 

[N6CO]

Am mode

 

[N6CO]

All GFCI receptacles were taken off line -
The main things that is making me pull my hair is - 1 month ago I had a
S-2 noise lev. nothing has changed in the house and when the breaker
is turned back on it takes 5 min's to ramp up to a S-9 , like something is heating
up - but with everything unpluged in the whole house from wall outlets and
no lights on etc . at least nothing else to do when it's raining outside (

 

[zbang]

The wavelength of a 4 MHz signal is 75 meters; at 17 kHz it's 18 kilometers. A directional antenna might be a trifle too big to use in a house.

That's why loops were invented . And it doesn't need much gain at all, just some nulls.