What is this?

  • 1
  • Problem
  • Updated 3 weeks ago
I've noticed a sudden jump in noise level on 15m over the last few days. So, I started to investigate and it looks like it may be internally generated.

I've pulled the plugs on all cables to 6400 except the ethernet and power cable, and it is still there!  The PSU is a linear design, not an SMPS. The Ethernet is cat6 directly to the PC and this has not changed for nearly a year.

In-band on 15m the noise level has gone up by about 1.5 s-point (now showing about S3-4) even with no antenna connected. However, I notice that out of band there is a massive bulge of noise -90dBm just above the 15m band....and this still is with NO ANTENNA connected whatsoever. Take a look at the pics.

I have also done a cold reset on the radio and removed and reinstalled the latest SSDR app just in case. What I am seeing here?  The radio is just a year old. Do I have a problem with it?




73 de Steve G1XOW
Photo of Steve G1XOW

Steve G1XOW

  • 315 Posts
  • 134 Reply Likes

Posted 3 months ago

  • 1
Photo of VE3DZP

VE3DZP

  • 56 Posts
  • 14 Reply Likes
You are not alone Steve I have the same problem. Made 15M un-operatable on the weekend. A fellow ham to the west of me had  the experienced the same. Going to try and track it down today.
Photo of Duane, AC5AA

Duane, AC5AA

  • 504 Posts
  • 120 Reply Likes
Does it also occur with a dummy load on the antenna connection?  (with the line terminated at 50 Ohms, that is)
Photo of Steve G1XOW

Steve G1XOW

  • 308 Posts
  • 134 Reply Likes
Duanne, exactly the same on open. short or 50 ohm dummy load to the antenna socket. Also tried the other sockets for XVTR and RXA...all the same.

The signal would have to be pretty massive for it to be anything external generating -82dBm in to a short circuited PL259 on the radio. So I assume it must be internal to the radio.

Also, nothing show at all in wide mode (when zoomed out) but when showing the whole of 15m plus a bit then the image is what you get.
Photo of Bob Craig, K8RC

Bob Craig, K8RC

  • 281 Posts
  • 115 Reply Likes
Any new electronics added to your house or neighborhood?

I could see my furnace fan's variable speed drive (yes, even with the antenna disconnected) until I added filters to the motor drive.   

Photo of Chris Tate  - N6WM

Chris Tate - N6WM, Elmer

  • 1014 Posts
  • 281 Reply Likes
Looks like the preselector is filtering out a good chunk of it.. looks like an external nose source
Photo of Doug K0DV

Doug K0DV

  • 169 Posts
  • 22 Reply Likes
Check your computer's power supply.  It may have lost the capacitors on the line filter.
Photo of Bill -VA3WTB

Bill -VA3WTB

  • 4619 Posts
  • 1093 Reply Likes
Does the WNB change anything?
Photo of Steve G1XOW

Steve G1XOW

  • 324 Posts
  • 135 Reply Likes
Bill,,

Yes WNB kills is but so does zooming out to "wide mode". Nothing shows at all in wide mode. But when showing the whole of 15m (with band pass engaged) then the image is what you get....even with -8dB of attenuation and the PL259 shorted.
Photo of Bill -VA3WTB

Bill -VA3WTB

  • 4619 Posts
  • 1093 Reply Likes
It still seems to be getting noise into the radio, even without an antenna. That is possible.
Do you have another PS to test with? I wonder if the PS is emitting a noise on that band.
Photo of Robert Lonn

Robert Lonn

  • 464 Posts
  • 177 Reply Likes
Not often talked about is the radio ground! I have a excellent ground system, 1.1 Ohms ground conductivity. That can make a big difference to how things operate in the shack... Flex has a good reason top have a ground connection on the rear of the radio. Also checking the Shack Ground at least once every spring and fall is like changing batteries twice a year in your smoke detectors... Another important thing to do, If you are TRAINED, and be safe, Is to check your circuit breaker box to be sure everything is tight, more with Aluminum Wire then copper, but I check mine at least once a year.. Let us know what your final fix is!!

Robert
Photo of Tim - W4TME

Tim - W4TME, Customer Experience Manager

  • 9478 Posts
  • 3665 Reply Likes
@Steve, it does sound like the noise source is external even though the antenna is disconnected.  Rather than hashing this out on the Community, I'd recommend you open a HelpDesk ticket so that one of our engineers can rule out anything wrong with the radio.
Photo of Steve G1XOW

Steve G1XOW

  • 324 Posts
  • 135 Reply Likes
Hi All,

Just wanted to check in on this and let everyone know where we are, and to help you avoid wasting time on this. As suspected all along the problem is indeed a defect for Flex to fix. Thankfully it looks like a software defect rather than another hardware warranty issue.

I've spent nearly 2 man-days chasing this ghost of fake interference. I have ripped my shack to bits and re-engineered almost every aspect of my station, new cables, local area samples of noise measurements, swapping PSUs, switching computers, new GPU, using other peoples radios for corroboration, isolating my shack from the mains, installing and reinstalling software, resetting the radio, profiles etc etc simply to prove what I already knew to be true.

The upshot is that this is a "known" (known to FRS that is) internal defect within the radio software, and obviously not local interference.

This issue has been logged as defect number: 6964

(Edited)
Photo of bobby

bobby

  • 97 Posts
  • 28 Reply Likes
Sorry for you waste of time, there is no radio worth that much time being wasted no matter what brand. This is just really sad .... but it is what it is and wont change in the future either ...
Photo of N5LB - Lionel B

N5LB - Lionel B

  • 243 Posts
  • 74 Reply Likes
Curious, how do you know it is a logged defect? Where did you find this?
Photo of Tim - W4TME

Tim - W4TME, Customer Experience Manager

  • 9478 Posts
  • 3665 Reply Likes
The information was provided to him by FlexRadio technical support.
Photo of Steve G1XOW

Steve G1XOW

  • 324 Posts
  • 135 Reply Likes
And here is another example of "fake noise" being produced on a Flex radio. This time it's on the 10m band. Don't worry if you see something like this, it isn't actually faulty it was designed that way!