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RF interference on 75m/80m
- Thread starter blindfire
- Start date
cockpitbob
NES Member
![[popcorn]](/xen/styles/default/xenforo/smilies.vb/043.gif "Popcorn [popcorn]")
70KHz could be a switching power supply.
The first thing I would do is run the rig off a car battery and throw the house's main disconnect. If the noise is still there, it's not coming from your house.
70KHz could be a switching power supply.
The first thing I would do is run the rig off a car battery and throw the house's main disconnect. If the noise is still there, it's not coming from your house.
DOH...completely missed that I said MHz...instead of KHz.
![[rofl]](/xen/styles/default/xenforo/smilies.vb/013.gif "ROFL [rofl]")
Boy, do I feel stupid now!
70KHz could be a switching power supply.
The first thing I would do is run the rig off a car battery and throw the house's main disconnect. If the noise is still there, it's not coming from your house.
I'll give that a try.
Thanks.
Not sure why the popcorn emoji though. (???)
cockpitbob
NES Member
I'm interested to see how this plays out and what our experts have to say.
Gotcha! Thanks.
I do have two PowerWerx 25 amp power supplies. One feeds the radio and the other feeds my 2m Amp. Both are on, obviously. I'll plug into my battery bank and see what happens.
I also do have a laptop on the desk with a power brick. I'll unplug that as well and see what happens.
The noise reminds me of that BPL noise... tech never really took off here, but it makes a racket. There are consumer devices which pump shit over inside house wiring, though... might make similar noise...
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Ok...I figured it out! I must have a grow house in the neighborhood!
http://www.eham.net/articles/32558
I do have a couple neighbors with solar, but I'd expect it to be more evident during the day when the panels are pumping out power.
Will keep you guys posted.
Keep the ideas coming, please!
http://www.eham.net/articles/32558
I do have a couple neighbors with solar, but I'd expect it to be more evident during the day when the panels are pumping out power.
Will keep you guys posted.
Keep the ideas coming, please!
F
Finalygotabeltfed
70KHz could be a switching power supply.
The first thing I would do is run the rig off a car battery and throw the house's main disconnect. If the noise is still there, it's not coming from your house.
This was my very first thought also and the same diagnostic experiment of using a battery.
Other than that, I'd first unplug every wall wart power supply in the house one at a time and see if it changes, then start turning off breakers one at a time.
If no luck finding it with either of those methods, I'd be looking towards any incoming cable tv lines and maybe make a sniffer coil to walk around the hood and see if someone might have a noisy plasma TV or other device in use, particularly if the noise goes away late at night when most are sleeping and a TV would be normally shut off.
My past experience is that its a power supply or wall wart.
AHM
NES Member
Now I'm in trouble, you took me seriously.
I was just teasing you C. that the QRM was just every Lid operating for Field Day.
Interference hunts can be epic. One of the MMRA repeaters was once getting hammered by a fatal design flaw (inappropriate diode or something) in a cordless phone recharging cradle in Sudbury. The saga was in a newsletter, but I can't find it online anymore.
The hams found the house, but the initially friendly homeowner suddenly froze up and wouldn't let them inside to narrow it down. IIRC, the FCC had to apply social lubricant ("you can let these helpful guys in, or you can let us in and we'll levy a fine"). I'm sure that that chapped the homeowner's grommet, but it got the job done. I don't remember if they fixed the charger or the homeowner threw it out to solve the problem.
Ok...I figured it out! I must have a grow house in the neighborhood!
eHam.net:
CO Ham Tracks,Resolves Interference from Pot Cultivators' 'Grow Lights'
Watch out - they may not have an NES screen name, but they could have more guns than you do.
Really, though: eliminate your house as a factor, and then eliminate your rig. (I once thought the WB1GOF/R/2m/FM repeater had a spurious transmission, and it turned out to be an image inside my rig).
73's...
70KHz could be a switching power supply.
The first thing I would do is run the rig off a car battery and throw the house's main disconnect. If the noise is still there, it's not coming from your house.
DING DING DING!!!!
Came home and plugged into my battery bank. Still heard the RFI...so I started turning things off.
Turns out, my PowerWerx power supplies are the culprit!
Stupid question, but I'm not above being stupid here...but if I don't have it set to a common ground and am depending on the ground from the AC outlet, will that be a possible source? In other words, if I hook them up to a common ground with the radio, will that eliminate the noise?
Thanks again!
cockpitbob
NES Member
You have a good idea to try, but the first thing I would do is google around. I bet someone has already been down this road.
F
Finalygotabeltfed
All the conductors going into and out of the power supply will be radiating the noise. Putting ferrite beads on all of them will most likely be the best remedy. How many?.....as many as it takes to diminish or eliminate the rf noise.
The rf needs to be choked off as close to the source as possible. You could also try a pi filter in the output leads. Two series chokes of sufficient amperage ratings bypassed with a .001mfd capacitor.
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cockpitbob
NES Member
I did a little googling around and most people have no noise problems with that supply, but some do. I think your idea of configuring for 1 ground (star ground) is your best bet. Strap the supply, radio and tuner if you have one, to the same place with short cables.
All I have is linear supplies. I keep thinking I want to get a nice small, light switcher, especially for portable ops, but then I come across something like this and I think "I just don't feel like dealing with another noise issue."
![[grin]](/xen/styles/default/xenforo/smilies.vb/041.gif "Grin [grin]")
.I did a little googling around and most people have no noise problems with that supply, but some do. I think your idea of configuring for 1 ground (star ground) is your best bet. Strap the supply, radio and tuner if you have one, to the same place with short cables.
All I have is linear supplies. I keep thinking I want to get a nice small, light switcher, especially for portable ops, but then I come across something like this and I think "I just don't feel like dealing with another noise issue."
Hey...you can just give me one of your power supplies, right?
Anyone recommend a good ground bus that I can then hook to my ground rod outside?
I have one of the Astron 30A switchers and never really had a problem with it, FWIW. Not sure of others. My only gripe with the astron supply was the temrinals on the back of the unit sucked, so I "upgraded" them with some lug type terminals that I found at a hamfest plus some hot glue to fill in the dead space around the back of the terminals.
-Mike
-Mike
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