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Offline Silversword

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Radio Interference Issue
« on: April 21, 2021, 02:58:31 PM »
Hi All,

I am a amateur radio operator and when I use my HF radio on 40 meters my receiving signal has a lot of noise that I cannot receive weaker stations.  When I turn off my BT system the noise goes away and I am able to receive those weaker station.

Is there a way to eliminate the interference coming from my BT system?

Any recommendations or suggestions will be greatly appreciated.

Aloha,

--Stan Y.
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Offline W0BTU

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Re: Radio Interference Issue
« Reply #1 on: April 21, 2021, 03:54:09 PM »
Could it be coming from a switching power supply that powers it?
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Offline Silversword

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Re: Radio Interference Issue
« Reply #2 on: April 21, 2021, 04:12:43 PM »
Could it be coming from a switching power supply that powers it?
Hi,

Thanks for the possible culprit. When I unplug the connector to the BT (Red) system the interference goes away and the power supply (wall wart) is still plugged in. I also have ferrite beads on the cable for all inputs to the system.

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Offline W0BTU

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Re: Radio Interference Issue
« Reply #3 on: April 21, 2021, 06:35:31 PM »
Is this a System Red? I've never owned one, but it seems I've read that the display can cause RFI. Can you turn it off?

Maybe a shielded cable has lost its ground, and it's radiating the noise? I suggest that you disconnect one cable at a time. If unplugging one of them makes the noise vanish, then that cable is suspect.

What kind of 40m antenna? Perhaps the coax shield is picking up noise near the receiver, especially if it's feeding a balanced antenna without an effective balun. An end-fed wire running all the way to your transceiver is notorious for picking up noise.

Is your choice of ferrite choke the right mix for suppressing 40 meter RF?

This is all I can come up with right now. I've never had my System Blues affect any ham band here. But I certainly believe you. Please keep us posted! :)
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Offline Silversword

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Re: Radio Interference Issue
« Reply #4 on: April 21, 2021, 07:08:01 PM »
Is this a System Red? I've never owned one, but it seems I've read that the display can cause RFI. Can you turn it off?

Maybe a shielded cable has lost its ground, and it's radiating the noise? I suggest that you disconnect one cable at a time. If unplugging one of them makes the noise vanish, then that cable is suspect.

What kind of 40m antenna? Perhaps the coax shield is picking up noise near the receiver, especially if it's feeding a balanced antenna without an effective balun. An end-fed wire running all the way to your transceiver is notorious for picking up noise.

Is your choice of ferrite choke the right mix for suppressing 40 meter RF?

This is all I can come up with right now. I've never had my System Blues affect any ham band here. But I certainly believe you. Please keep us posted! :)

Hi,

Thanks for your suggestions and recommendations.  Will try to isolate it via removal of cables first.

The display goes off after about 30 seconds after it comes on from time to time.  When it is off the interference is still there with it on or off. Don't know if the display is working in the background when it is in the off mode.

The 40 meter antenna is a full length dipole with a 1:1 balun.

I do have about a s5 noise level at my location.  With the BT system my noise level goes up to s7 and sometimes it pulses when the red blinking LED is blinking.

I don't know what type of ferrite beads are, but it did some good to reduce the noise just a hair.

Maybe I should retire my Red system for a Blue one. Might have to do the H and E fields system as well.  Big changes to do all that.

Aloha,

--Stan Y.
  KH6HHG
  Maui, Hawaii

 

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Offline davidmc36

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Re: Radio Interference Issue
« Reply #5 on: April 21, 2021, 07:10:35 PM »
Could it be coming from a switching power supply that powers it?
Hi,

Thanks for the possible culprit. When I unplug the connector to the BT (Red) system the interference goes away and the power supply (wall wart) is still plugged in. I also have ferrite beads on the cable for all inputs to the system.

--Stan Y.
   KH6HHG
   Maui, Hawaii

Could there be very little EM produced by the suspect power supply when just plugged in, no load?

Maybe a cheap audio device of some sort held right against the power supply while unloaded would sense the EM and be heard on its speaker. Like a small AM radio? ;)

Offline WA7FWF

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Re: Radio Interference Issue
« Reply #6 on: April 21, 2021, 07:11:27 PM »
Hi, I have a RED system and my 40M vertical is 75 feet away and I do not notice any noise, but I do have some powerline noise so maybe that is masking it.  What I would suggest is that you unplug everything but the power and see if you have the noise, if yes then set the display brightness to off or 100% and go from there with filters etc. If the noise goes away with just the power on, then plug in the sensors one at a time and then the ethernet and gps (if using an external antenna) see which one is causing the noise, then put your ferrites on that line or troubleshoot more.

Kevin

Offline Silversword

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Re: Radio Interference Issue
« Reply #7 on: April 21, 2021, 09:12:46 PM »
Hi,

David, with the wall wart PS plugged in and not powering the BT Red system no EM from it.  When it powers the system the noise is there by about 2 s units.

Thanks for your suggestion for an AM radio have done that and when the system is powered the noise is there, with the PS plugged in and not powering up the system, no noise.

I will have to try to figure out on how to use my Tiny SA as a tool to see how the spectrum looks like near the BT system.

Kevin, I will try to see if putting the display to off and see if that will cure it.  Is the display working in the back ground as it is off normally but comes on at times?  Still don't know if that is the issue. Will try to unplug all of the sensors to see if anyone will cause the noise to go away. My 40 meter dipole is about 40-50 away from my radio and the BT system.

Thanks for both suggestions and recommendations.

Aloha,

--Stan Y.
   KH6HHG
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Offline WA7FWF

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Re: Radio Interference Issue
« Reply #8 on: April 21, 2021, 09:26:21 PM »
Stan,
  Tthere is a known issue that the PWM for the backlight can cause some noise but turning it off or setting to 100% takes it out of the equation.

Offline Silversword

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Re: Radio Interference Issue
« Reply #9 on: April 22, 2021, 01:20:20 AM »
Stan,
  Tthere is a known issue that the PWM for the backlight can cause some noise but turning it off or setting to 100% takes it out of the equation.

Kevin,

Here is the current settings for the LCD. Will let you know tomorrow to see if this settings solves my issue with my s meter noise factor.

Thanks for your input.

Aloha,

--Stan Y.
   KH6HHG
   Maui, Hawaii
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Offline zoomx

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Re: Radio Interference Issue
« Reply #10 on: April 22, 2021, 04:36:07 AM »
David, with the wall wart PS plugged in and not powering the BT Red system no EM from it.  When it powers the system the noise is there by about 2 s units.

Maybe if the PS is simply plugged doesn't emit RF because very little power is used, can you test it powering another device?

Offline Silversword

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Re: Radio Interference Issue
« Reply #11 on: April 22, 2021, 04:03:15 PM »
Hi All,

Changing the LCD settings made no difference. Switched out the power wall wart with another PS, made no difference. Used another device (cell phone) with the one that I use for the BT system and that did not cause RF S meter to rise to 2 S units, only when attached to the BT system my S meter rises 2 units.

Right now, I am stumped, there might be other places within my system to check, but for now, I will unplug the BT system while I am on my radio and plug it in when I am done.

Thanks all for suggestions and recommendations for my dilemma.

Aloha es Best Regards,

--Stan Y.
   KH6HHG
   Maui, Hawaii
 
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Offline SoMDWx

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Re: Radio Interference Issue
« Reply #12 on: April 22, 2021, 05:59:22 PM »
Do you have any fluorescent light on in this space or near it? Bad ballast possibly....

Offline Silversword

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Re: Radio Interference Issue
« Reply #13 on: April 22, 2021, 07:38:35 PM »
Do you have any fluorescent light on in this space or near it? Bad ballast possibly....
Hi Jim,

There is a fluorescent light about 20 feet away from my BT system. Turning it on or off does not make a difference with the s unit on my radio with the BT system on.

Thanks for the thought.

--Stan Y.
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Stan Y. - KH6HHG - Maui, Hawaii --- Blitzortung ID: 993 --- FlightRadar24 ID: F-PHOG1
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Offline vreihen

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Re: Radio Interference Issue
« Reply #14 on: April 22, 2021, 09:10:51 PM »
Silly question - Is the BT case/chassis grounded?  Can you put some extra shielding like a spaghetti pot over it to see if it helps?????
WU Gold Stars for everyone! :lol:

Offline NK7Z

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Re: Radio Interference Issue
« Reply #15 on: April 23, 2021, 07:44:08 AM »
I wrote up a small entry here:
https://www.nk7z.net/rfi-now-house-cleaning/
on removal of stray RFI from the shack...  It may help you.

Offline SoMDWx

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Re: Radio Interference Issue
« Reply #16 on: April 23, 2021, 09:25:10 AM »
That is a great article to read! Lots of testing i see.....   =D>

Offline NK7Z

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Re: Radio Interference Issue
« Reply #17 on: April 23, 2021, 09:41:07 AM »
Thank you!  There are three parts to it as well...

Offline Silversword

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Re: Radio Interference Issue
« Reply #18 on: April 23, 2021, 01:12:19 PM »
Hi All,

Silly question - Is the BT case/chassis grounded?  Can you put some extra shielding like a spaghetti pot over it to see if it helps?????

Possible issue to make a Faraday cage for the BT system. Thanks for the thought.

I wrote up a small entry here:
https://www.nk7z.net/rfi-now-house-cleaning/
on removal of stray RFI from the shack...  It may help you.

That is a great read.  At least I know that my BT system is one of the culprit. I have done some isolation testing around my place and it seems that a lot is coming from either utility poles and PV systems around my neighborhood. I have reported our power company to some of the poles that have a high noise level and they have done some maintenance on them and that has reduced my HF noise level.  At time my noise level was over s-9 and now it is simmering at about s-4.

Anyway this is on another subject and I just wanted to know what I could do to reduce my BT system RF.

Best Regards,

--Stan Y.
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Offline Cutty Sark Sailor

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Re: Radio Interference Issue
« Reply #19 on: April 23, 2021, 10:01:20 PM »
Hey...Lonessme Stan!  :D
....looking for ground loop effect....????
By any chance, is the BT Wall Wart plugged into the same AC Circuit that your receiver is on?
Also, if you're grounded to an AC ground?
What happens if remove the ground?  Maybe try coldwater pipe
Explore if you're using shielded RJ45 cables, and the one to your router/modem is shielded.  Try unshielded there, or vice-versa...
Good Luck!
Mike
« Last Edit: April 23, 2021, 10:02:54 PM by Cutty Sark Sailor »
 

Offline W0BTU

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Re: Radio Interference Issue
« Reply #20 on: April 24, 2021, 06:21:42 PM »
Except for the ground you mentioned, this is what I've been thinking all along, Mike. Thanks for mentioning unplugging the cables again.  [tup]

Stan, the size of your lightning receiver is only a very small fraction of a wavelength at 40m. Thus, with all the cables unplugged (except for the 5V DC PS), unless it is in close proximity to something unshielded your ham shack (like my MFJ antenna tuner), direct radiation from the receiver itself is very unlikely to be strong enough to reach your dipole. It has to be coming from one (or more) of the cables that are plugged into this receiver. :)

Do you still hear the noise with only the power cord plugged in?

There was a recent post on the other forum about a fellow whose noise was coming from a bad cable.
« Last Edit: April 24, 2021, 06:25:49 PM by W0BTU »
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Offline Silversword

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Re: Radio Interference Issue
« Reply #21 on: April 24, 2021, 08:31:17 PM »
Hey...Lonessme Stan!  :D
....looking for ground loop effect....????
By any chance, is the BT Wall Wart plugged into the same AC Circuit that your receiver is on?
Also, if you're grounded to an AC ground?
What happens if remove the ground?  Maybe try coldwater pipe
Explore if you're using shielded RJ45 cables, and the one to your router/modem is shielded.  Try unshielded there, or vice-versa...
Good Luck!
Mike

Hi Mike,

Thanks for your suggestion and recommendations.  The wall wart is connected to the same source that comes from my UPS that also supplies power to most of my stuff.  My ground rod is an 10' copper rod that is tied into my system.  It is usually kinda wet where I am located so there is a good ground that I know of.  I have isolated the grounding to the BT system from the rest of the system with no effect.

All of the cables that is used by the BT is shielded RJ45's. I have not tried unplugging the cable to the router/modem.  Will try that and see what happens.  Will let you know the outcome when I do that.

Thanks again for your suggestions.

I may not be the only BT systems here in Hawaii as I saw there are three more here but don't know how active they are, as when monitoring some strikes, I do not see any lines from those sites when I have lines going to strikes in the Eastern Pacific. There is one on the Island of Kauai, one on the Island of Hawaii and one more here on Maui, on top of Mount Haleakala.  Hope that they will become more active....

Aloha,

--Stan Y.
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Offline Silversword

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Re: Radio Interference Issue
« Reply #22 on: April 24, 2021, 08:39:55 PM »
Do you still hear the noise with only the power cord plugged in?

There was a recent post on the other forum about a fellow whose noise was coming from a bad cable.

I have not completely disconnected all of the cables to and from the BT system yet.

Will have to see if there is the interference noise coming from the BT system with only the power plugged in. If on noise will plug in the GPS, then the cable going to the router, then to the antennas.

Will let you know the out come when I have the time to do that.

Also, thanks for your suggestion and recommendations.

Aloha,

--Stan Y.
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Offline SoMDWx

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Re: Radio Interference Issue
« Reply #23 on: April 27, 2021, 11:02:51 AM »
I Love it! This is like waiting for the next episode of a soap!

Offline Silversword

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Re: Radio Interference Issue
« Reply #24 on: April 27, 2021, 09:00:17 PM »
Hi All,

Thank you all for sticking with me with my issue.

Finally got a chance to take the system cabling out with only the power attached.

With the display on the signal level was a S-9 on my radio.

When the display went off the signal level went down to a S-5, which is probably coming form other sources outside or within my house, which is the norm for this testing.

Next connected the GPS, no change with the signal level.

Next connected the modem/router, no change with the signal level.

Next connected the H antenna to amp 1, the interference came on at about a S-8.

Disconnected the H antenna and connected the E antenna to amp 2, signal level dropped to S-5.

Moved the E antenna to amp 1, system did not like that but the signal level stayed a S-5.

Then put the E antenna to amp 2 and put the H antenna to amp 1, the interference came back on.

Looks like the culprit is the H antenna is the issue. So have that off for now and will have to go the roof where the H field antenna is located and check on the amplifier in the box of the the ferrite core loops are located.

Attached is what I have the settings for both amplifiers.

 [ You are not allowed to view attachments ]

Hope all this makes sense.

Thank again for all of your inputs.

Will see what I can do with the H field antenna system.

Aloha,

--Stan Y.
  KH6HHG
  Maui, Hawaii

« Last Edit: April 27, 2021, 09:03:05 PM by Silversword »
Stan Y. - KH6HHG - Maui, Hawaii --- Blitzortung ID: 993 --- FlightRadar24 ID: F-PHOG1
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