Discussion in 'Amateur Radio News' started by IW2BSF, Apr 17, 2017.
a nice video on RFI in 40 meters
What was it, and what was it used for ? Should have explained at least that part.
Looks like a switched mode PSU, (noisy). Used on many things these days.
It's a common and never-ending battle. One thing I was surprised by is how bad things can be on VHF. My HF reception is pretty reasonable, so I thought I didn't have any bad noisemakers. My 2 meter reception wasn't stellar, but I didn't have anything to compare it to, and it was good enough for my closest couple of repeaters. The thing is, a noise source may not sound like anything when you listen to it using an FM receiver -- it just covers up signals and makes them seem weaker. One evening, I happened to listen to a 2m simplex station in the car on my way home, and noticed that he disappeared as soon as I got to my driveway, and he reappeared when I drove a few dozen yards away. Got out the handheld scanner, tuned it to AM mode, and made a search, flipping breakers. Discovered a switching regulator for a light that was raising the noise floor on 2m. I built a linear regulator to replace it, and now I can hear dozens more repeaters, and my commercial FM broadcast reception is better, as well.
More details of my noise problem here: http://ag6qr.net/index.php/2017/01/02/chasing-noise-sources-part-1/
In the last 13 years I have lived in 3 different places.
The first place was terrible for noise , place 2 was OK ,, and my current place was a total DISASTER.
I live at a commercial property with a small supermarket and several other small shops , 2 workshops , and 30 meters away there is a factory.
During the day and for most of the night the roads around me a busy with traffic coming to and leaving this area.
I can't complain too loudly because I work at these places , and I must live on site - its my job.
But the noise levels have been off the charts ,, and are all locally made.
I have now been here 3 years and have been reducing the noise sources one by one.
Some I can't fix because I don't have complete access or authority but its not bad.
A portable SW receiver in my house is still 20dB over 9 across all of HF with noise , but with my external antenna I have essentially no noise.
Was it easy , cheap and fast to fix these problems - NO.
Was it worth the effort - SURE.
When a Ham says that he has noise and its bad and he can't do anything about it , , , I just smile - Really ?
I recently got on HF again at my other house in the trees in Auburn, CA. When I listened to 40 meters, my noise was 20 over S9 throughout the entire band. I have no nearby neighbors there, so I started at the circuit breaker box. When I turned of the garage, the noise dropped to S4. Then it the garage, which is NOT even close to my radio or antennas, I started unplugging stuff. The noise problem was caused by two battery maintainers that are used on my little used vehicles.
The noisy battery maintainers are this model.
So now, I simply unplug them B4 getting on the air.
-Don- Reno, NV
I've got a BAD 15m noise source here. Its driving me crazy to figure out what it is.
I would think it is the switching PSU but I've used it in other locations with no problems. I don't have another one to try but I'll see if I can adjust this one.
Tried 3 different rigs, 4 different antennas. Same problem.
This is in the 15m JT segment... around 21.076. This is with the RF squelch/gain turned all the way down. S-9 over 80+.
I had the following appear on the bands of 20, 40,80, 160M (more than likely everywhere in between!):
The culprit was a new touch lamp makeup mirror my daughter had in her bedroom:
It's NO LONGER a touch lamp, I gutted the RFI generator and replaced it with a simple ON/OFF switch. There is now
peace AND quiet on the bands locally!
73 Kriss KA1GJU
When I sprayed my yard for weeds, I sprayed all my rf with the same spray. Weeds are dying. I'm giving the rf another dose next week if it is still there.