I'm opening a new shop out here in Northern Virginia, and I took the opportunity of installing an outdoor FM antenna to add a scanner antenna. I'm a radio nut, and I like my FM, but where I am at the convergence of the Shenandoah and Potomac rivers, I'm in a triangular valley, surrounded on all three sides by mountain ridges... FM reception is terrible, to say the least. Scanning is good, however, as I'm surrounded by repeaters on those mountains! Anyway, I opted for an outdoor antenna on a 10ft. mast on the outside of my steel building. At the last minute I decided to top it off with a cheap discone. Got it mounted and set up last night, and decided to try it out this morning. Well... The Ubiquiti NanoStation M2 that I mounted adjacent to the antennas (to wirelessly share my Internet connection from my house across the street) is splattering the whole 140-150mhz band with a whine! Power is turned all the way down to -23dbm on both NanoStations, and I'm using shielded Cat6 and double shielded RG6 on the antennas. Very annoying and disappointing... Anyone have any ideas or suggestions?
New antenna install - from excited to disappointed
- Thread starter ur20v
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It appears that your scanner antenna installation is working fine, but just to ensure that is really the case, and that what you have is an interference problem from the Ubiquiti bridge: If you shut down the Ubiquiti system does the problem with the scanner go away completely? To make the interference go away do you need to shut down both ends of the Ubiquiti bridge, or just the transmitter on the steel building next to the antenna? And by "shut down" I mean not only turning of the Ubiquiti bridges, but also unplugging any "wall wart" AC transformers that may be used to power them. If you definitely isolate the problem to the Ubiquiti bridges, then here's the next question: Are you using good quality shielded Ethernet cable from each bridge device and with all the computer connections on each end of link? These are special shielded cables with metallic shielding that even extends over the RJ45 connectors, not your average cheap Ethernet patch cable you can buy anywhere. Take these steps and then come back here and tell us all if it helped or not.
mikepdx
Member
I'm thinking the obvious answer:
re-locate the M2 much further away from the antennas,
or the antennas from the M2.
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I determined it was the M2 by unplugging the POE injector. The whine went away immediately, squelch on the scanner closed and it went about scanning. The power on the M2s was initially set at -5dbm, and turning it all the way down to -23dbm (where it should be for my distance), the whine has decreased in level, but it's still there.
Unfortunately I dont have much option of moving either - power lines cross over the rear of my building, and the M2 has a relatively narrow unobstructed view of the M2 on my house due to the angle, adjacent buildings and trees.
I may try re-routing the Cat6, as right now both coax cables and the cat6 come in the building at the same point and run side-by-side for 6-8 feet.
Unfortunately I dont have much option of moving either - power lines cross over the rear of my building, and the M2 has a relatively narrow unobstructed view of the M2 on my house due to the angle, adjacent buildings and trees.
I may try re-routing the Cat6, as right now both coax cables and the cat6 come in the building at the same point and run side-by-side for 6-8 feet.
mikepdx
Member
I've solved many an interference problem by
just re-locating ethernet cables...
sometimes just by inches.
Are the coax shields & masts at ground potential?
I wonder if the shield/mast is picking up the
junk and re-radiating it.
Another thought is an operating
normally, but noisy (to a scanner)
power supply powering the M2.
Much luck with the puzzle.
I've been there...
The other thing to do is the Ubiquiti NanoStation M2 change the channel to see if the harmonic goes away is this the 2.4 gig or the 5.0 gig? You never did say what scanner you were using? You can also turn the Ubiquiti 90 degrees to change the signal pattern.
The NanoStaion is an M2 so it's 2.4ghz. My scanner is a Uniden BC436HP.
I originally had it set to channel hop and all the other funny little options Ubiquity offers, but after doing a spectrum analysis with the built-in tool, I decided to lock it down on channel 4. Seems there is a bunch of 2.4ghz congestion in this little area, which doesn't surprise me. But there was a nice empty spot on channel 4, so I snagged it.
Luckily the whine doesn't drown out any legitimate traffic in that 10mhz swath, it just stops the scanner on every preset in that chunk. I'll update when I get the cat6 relocated.
Unfortunately I'm using the molded-in pipe mount on the back of the NanoStation with simple j-pole satellite dish mounts, so rotating them isn't an option.
It can be done with angle iron I have made several Ubiquiti brackets in my day. I would still change channels. I built Video IP camera system running 100 IP Cameras with over 30 wireless total traffic 450MB with 45MB wireless in 3 mixed zones all on different channels all working happy together as close as you are set your password and let it run. You might have some luck swapping m2's just swap the locations.
prcguy
Member
Try some #43 snap on chokes on your CAT5 cable outside right at the unit and also inside at the power injector. You need at least 3 snap on chokes to make a big difference at VHF unless you can loop two turns through one choke and then two chokes one or both ends may fix the problem if its conducted via the CAT5 cable.I
It could also be the wall wart switching power supply causing the problem and you could prove that by disconnecting the CAT5 at the outdoor unit then plug in the power supply. If that's the case you might be able to put snap on chokes on the power supply or find a linear supply that will power the system.
If its radiated from the outdoor unit and not the CAT5 then you would have to relocate the outdoor unit or scanner antenna as others mentioned. I've used snap on chokes to completely fix RFI problems in the VHF range from new Cree LED flood lights and they can work very well
prcguy
It could also be the wall wart switching power supply causing the problem and you could prove that by disconnecting the CAT5 at the outdoor unit then plug in the power supply. If that's the case you might be able to put snap on chokes on the power supply or find a linear supply that will power the system.
If its radiated from the outdoor unit and not the CAT5 then you would have to relocate the outdoor unit or scanner antenna as others mentioned. I've used snap on chokes to completely fix RFI problems in the VHF range from new Cree LED flood lights and they can work very well
prcguy
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Thank you, I'm going to try that suggestion, though all I've been able to find so far are mix 31 chokes. But your post brings up a new issue - the 8 LED floodlights I'm about to install outside to light up the walkway and my sign.
Ain't technology great? ;-)
Ain't technology great? ;-)
I've been wondering about all the electronics in LED lights if they're going to end up as headaches for us radio people especially in apartments if everyone is using them.
what is a Ubiquiti NanoStation M2? I've not heard of those before.
There will definitely be some issues with them. My house is full of high quality Edison base LED bulbs, and they give me no trouble at all. My parents have a surprisingly expensive surface mount over-counter LED fixture which uses a wall wart. Whenever it's plugged in, it QRMs pretty much the entire HF spectrum. Nothing but big-gun local AM stations can get through it.
Back on the original topic - I hope that rerouting the Cat6 cable, or remounting the Ubiquiti helps with your noise problem. Another alternative - Could you add an arm, extending away from the mast, to mount the Ubiquiti? If the noise is coming from the box directly, that may also help.
wb6uqa
Member
FM ANTENNA
Many directional tv antennas also include a directional fm antenna. Just add a rotator and you have a dx fm antenna.
Many directional tv antennas also include a directional fm antenna. Just add a rotator and you have a dx fm antenna.
I have motion sensor lights at the corner of my detached garage, about 100 feet from my shack and about thee same distance from various other antennas. There are 3 high power LED bulbs in the fixture and they don't appear to cause any RF interference...at least not that I've stumbled on yet. I have LOTS of other RF interference producers, most of which there's nothing I can do about, so if the LEDS are producing interference in the same area(s) as some of the others, I'm unaware of it.
I've gone through every RF interference elimination technique I thought possible, many of which helped. I'm just in a dense RF area. I've removed nearly all my wall warts, choosing instead to use a large linear supply and two smaller RF quiet switching supplies (the kind where the noise can be moved if it does interfere, which I've had to do a few times). I also ended up selling a TV very soon after I bought it, but not soon enough to just return it :-(, because it was a huge noise generator in many parts of the spectrum. I would bet that if I took that TV to the FCC for emissions testing, they'd revoke the approval. I'm not sure if it's the FCC or some other agency, but you get the point.
Other thing that have helped a lot are what another poster already mentioned: ferrite beads. You can never have enough ferrite beads. I probably have several dozen of them attached to numerous devices, all of which had some positive impact. BTW, that's about the best, easiest, least costly thing you can do to help with interference.
Another thing you might be able to try, if you have enough coax available going to your Ubiquiti NanoStation M2, is creating a 1:1 balun with the coax. If there's signal coming back down the coax shield from the device, a 1:1 choke balun will get rid of it. That's something that costs you nothing, other than time. I'm not sure how many turns will be needed at 2.4GHz, nor the coil diameter. You'll have to do some research on the internet to find out, but I'd guess the information is readily available. If you do have interference from RF on the coax shield, you could also just buy a 1:1 choke balun instead of building your own. Not free, but certainly less time consuming. If you know someone who has one available that you could borrow, you could test it to see if it helps.
73 - David, AG4F
I've gone through every RF interference elimination technique I thought possible, many of which helped. I'm just in a dense RF area. I've removed nearly all my wall warts, choosing instead to use a large linear supply and two smaller RF quiet switching supplies (the kind where the noise can be moved if it does interfere, which I've had to do a few times). I also ended up selling a TV very soon after I bought it, but not soon enough to just return it :-(, because it was a huge noise generator in many parts of the spectrum. I would bet that if I took that TV to the FCC for emissions testing, they'd revoke the approval. I'm not sure if it's the FCC or some other agency, but you get the point.
Other thing that have helped a lot are what another poster already mentioned: ferrite beads. You can never have enough ferrite beads. I probably have several dozen of them attached to numerous devices, all of which had some positive impact. BTW, that's about the best, easiest, least costly thing you can do to help with interference.
Another thing you might be able to try, if you have enough coax available going to your Ubiquiti NanoStation M2, is creating a 1:1 balun with the coax. If there's signal coming back down the coax shield from the device, a 1:1 choke balun will get rid of it. That's something that costs you nothing, other than time. I'm not sure how many turns will be needed at 2.4GHz, nor the coil diameter. You'll have to do some research on the internet to find out, but I'd guess the information is readily available. If you do have interference from RF on the coax shield, you could also just buy a 1:1 choke balun instead of building your own. Not free, but certainly less time consuming. If you know someone who has one available that you could borrow, you could test it to see if it helps.
73 - David, AG4F
Sorry, I just re-read my post and realized it was unclear - the choke balun goes right at the antenna, not at the NanoStation (regardless of whether it's a coax balun or a commercial, store bought balun).
73 - David, AG4F
73 - David, AG4F
Here's a link to a good article about RFI: http://audiosystemsgroup.com/RFI-Ham.pdf. It's rather lengthy (65 pages, PDF), but does have some excellent information about RFI causes and cures.
wb6uqa
Member
FM ANTENNA
I would buy a different wi fi router . All that stray rf is not healthy.
I would buy a different wi fi router . All that stray rf is not healthy.
It is not a wifi router it is a 2.4 secure wireless bridge point to point LAN
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