Strange noise occurance

Steve W6SDM · November 2014

I am in a very rural location and have done most everything to keep the station quiet. I use an isolation transformer on the AC, and most of my peripherals are powered off of a non-switching power supply rather that wall worts. My noise floor is usually below 3 depending on the band and the time.

However, I have birdie that comes up on the low end of the panadapter and travels to the high end. Of course, I only hear it as it passes the frequency that I am tuned to and it's a high pitched sweeping sound. I can see it on the waterfall after it has traveled the panadapter, at the bottom of the waterfall as a black "bump" in going left to right.

What kind of noise source should I be looking for? I have a small RF detector but there are so many places around the house to check.

Dave KD5FX · November 2014

I have those around here too. Turned out to be a battery charger in my garage so I put a remote on/off switch on it. I've noticed that the battery chargers for my cordless drill and cordless trimmer also put out lots of noise. So I put them on a power **** which I turn off except for the hour or so it takes to charge the battery.
Survey your whole house, look for those little wall warts that charge this and that or power whatever. Unplug them all and then see if you still have the noise. If so, it could be coming from a neighbor!
Good luck, you'll need it.
73, Dave KD5FX

Jim KJ3P · November 2014

I have one of those as well. In my case, I'm pretty sure it's a switching supply for the local cable company. It's located less than 100 yard away on a power pole. I've watched the average frequency of it change with temperature, too. In my case, it repeats every 100 kHz all through the 40-meter band (the AC line between it and the nearest transformer is about 1/2-wave on 40, so it seems to resonate there). It is sort of a "swishy" sound when you listen to it with BFO.

RoyS · November 2014

I have a similar situation on my 6300. If I compress a slice down to where I see 7 MHz on my panadapter screen, I see a signal (I have seen as many as 3) start out in the AM broadcast band and travel as high as 29 MHz. Movement is about 1 MHz per 10 seconds. After a short delay, the transmission repeats. This appears to me to be an intentional transmission and may be connected to someone doing research on propagation. Just a thought.

Tim - W4TME · November 2014

Could be an ionosonde http://en.wikipedia.org/wiki/Ionosonde

Bill-W9OL · November 2014

THAT was going to be my suggestion but you beat me to it.

Steve W6SDM · November 2014

Well, unless it's an ionosonde, or unless it's extra-terrestrial, it's something around my house. My nearest neighbor is about 300 yards away.

The good news is that it isn't much of a nuisance. Their presence only lasts on a particular frequency for milliseconds. As I was working the contest this weekend, I kept watching them travel up the band and thought it was one more thing I could eliminate.

I do have the chargers for my iPhone, iPad, and various other battery devices in my shack. I will be playing process of elimination with those to see if it makes any difference at all on my noise level.

Andrew VK5CV · November 2014

A few nights ago I noticed a broad signal repeated over the 80m band. The little Tecsun PL360 (a firmware SDR) rapidly lead me to a USB output wall wart of discount origins. In VK without the protection of FCC rules these devices often save a few cents on the filter components by leaving those bits of the board empty.

N7CXI · November 2014

With "voluntary" FCC compliance, the rules don't protect much these days here in the states, either.

73,
Jim N7CXI

Reg · November 2014

I have a noise source that repeats every 70 kHz from about 3 MHz up to 36 MHz. It is about 20 kHz wide and drift is very slow. There is no audio associated with it regardless of which mode I listen in or try a BFO. What it does I raise the noise floor by 15 to 20 dB. It doesn't seem to "interfere" with signals but weak signals which fall on those frequencies are buried much deeper down in the noise. The project for this week is to use the Pixel PRO-1b to try to DF it. Hopefully, it will be on a friendly property. Has anyone identified a signal with this kind of profile?

Reg

David Ramer, VE7YA · November 2014

I have this very same problem myself. I just got my 6700 two weeks ago and I am astonished at how much of the RF spectrum this signal takes up and how much noise it creates. I have detected it as low as 300 KHz and seen it as high as 30 MHz. I have not followed it past 30 MHz. I do not see it at 50 MHz. Weak signals are impossible to hear at my location. Quite frankly, I want to shut down whatever it is and I am considering making a formal complaint as it not only interferes with amateur frequencies, but commercial as well. I am located on the southern end of Vancouver Island. I don't know if it has anything to do with oceanographic work or military use. It will be a while before I am able to do any DFing and track it down.

I have also seen a signal as described earlier that scans from low to high frequencies on all bands. I have also seen a signal that scans from high to mid frequency on 10 Meters. It is strong enough to be an annoyance in a qso.

The panadapter has really opened my eyes to just how much noise and crud there is out there on HF frequencies. I have a suspicion that some of the noise is related to the use of grow lamps, and I want to track those down. My ICOM IC-737 shows an S9 noise level on 40 meters and S5 on the 6700 which makes 40 Meters impossible for qso's with weak signals. 20 Meters is slightly better, but still weak signals are impossible to hear.

David, VE7YA

James Kirk · November 2014

Grow lights for marijuana

David Ramer, VE7YA · November 2014

I was tempted to say that, but there may be some people who grow orchids or other exotic plants. Growing marijuana is still considered illegal outside of government approved businesses in Canada. I have a concern about just how to approach such a situation, or how to differentiate between the exotic plant grower and the illegal marijuana grower before touching the door bell.