RF WNB Noise issue

Ray - K6LJ

I have recently noticed that I have developed a buzzing sound mostly noticed when on my Titan vertical. The Hex has much less of this effect. It was the first time I have tried to use the WNB filter and it really helps. The first pic here is with the WNB off.



Next I turned ON the WNB set at about 92 and things are much improved.




Next I zoomed out all the way to see as much spectrum as possible. And disconnected the antenna. Selected RxB. could also select the dummy load and would look about the same as selecting RxB. Turned off WNB.




Turned on WNB and things were greatly improved.



I have tried to find the source with an AM radio and pulling the wall warts, Powering off devices etc. I have not tried connecting the radio to a battery but the house really has not added devices since this issue started.

I live somewhat out away from the city on a 2 acre lot so this issue could be coming from one of the neighbors or me or the Power Pole in front of my house.

I can still operate pretty well because of the WNB Filter however I would like to find the source.

I actually suspect the power pole in front of my house but just using the AM radio will buzz when I get to near anything.

I see this MFJ noise finder on the web. Has anyone used this? Is it worth the money to help locate the noise?



Thanks will appreciate any advice provided.

MIchael Ryan

The little handheld antenna/recvr combo is very sensitive to polarity (vertical / horizontal) as  you might imagine and as I recall operates at or around 137mhz, not far off the aircraft band. They recv is not very selective, you will hear aircraft if you are near an airport (even though they are on AM I think) and also nearby FM broadcast stations if you point it in the direction of one.  If you have neither it may be helpful.  The units run off a 9v battery so don't forget to turn it off when done with it or the battery will be shot the next time you want to use it. One thing I have learned about noise sources is to look inside your OWN house first. Too much to cover here but you may find major offending sources right in the living room. The power supply for that electric recliner you like so much. Or the wall wart that charges your Iphone and powers your Amazon Alexa. The power pole out front is always the easy to blame culprit. If you want some real help finding / hunting down noise check out the info on https://www.rfiservices.com/   Happy hunting.  -Mike, K4CVL 

Steve Sterling

When in RxB (or on the dummy load) your baseline is pretty high at -108dbm or so. Typical signature of the pre-amp gain setting at 0db so you are seeing the floor of the A-D converter, not an external noise source. Bump the gain up to +10db  (under left column ANT. settings) and you should see at least it drop when on the dummy load. Not saying you need that gain when actually hooked to an antenna, but when hooked to dummy load and gain adjusted for very low signals you should see a baseline in the -135 to -140dbm range.

Ray - K6LJ

Thank you

Ray - K6LJ

Thanks will try tnx 4 the link

KF4HR

Ray - I've been experiencing (what I assumed was) home electrical interference issues, which have resulted in fairly high noise levels on the lower HF bands (160, 80, and 40M), so to help track down this potential noise I purchased a MFJ-856.  I wasn't expecting high quality construction, and I got pretty much exactly what I expected (hi), but the unit went together fairly easily and does work.  I was able to find some devices around my home (wall warts, a dehumidifier, etc) that were generating RF noise, although when I disconnected these devices I found I had no difference in my Flex-6700's noise floor (on any of the  bands).

I'm not sure if this is true but I recently read that due to the low sun spot numbers, the condition of the earth's ionosphere is currently allowing certain types of radiation from space (solar particles and such) to enter our atmosphere, which under better ionospheric conditions normally wouldn't, and this may be responsible for the relatively high HF noise levels on certain bands.