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baumie
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interference to two way radios

Sat Dec 03, 2011 10:27 am

Hi
I'm co-locating with a guy with a two-way radio repeator and now all of a sudden he's getting a Hissing sound on his radios, but the moment I put my mikrotik of its quiet again. Is this possible at all I mean I'm on 5.8Ghz and he's on 124Khz. Could it be that the board itself coul generate noise BTW its a RB433 with one R52HN and two normal R52's all an 5.8Ghz.
thanks
 
changeip
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Re: interference to two way radios

Sun Dec 04, 2011 4:49 am

maybe your power supply? switching power supplies are very noisy.
 
baumie
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Re: interference to two way radios

Mon Dec 05, 2011 8:50 am

Ok the powersuply is a 24v battery charger with two deepcycle batteries. I have got a toggleswitch to switch supply to the router on and of so the power supply stays on and as soon as the router goes of the noise stops
 
changeip
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Re: interference to two way radios

Mon Dec 05, 2011 6:45 pm

thats not a good test because you dropped the load on the power supply (its not producing). try using a different power source just temporarily to see if it helps. Maybe run them directly from battery without the charger on.
 
warwickw
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Re: interference to two way radios

Thu Dec 08, 2011 9:48 am

Are you using shielded CAT5 ?
Is your shielded CAT5 connected to the common ground ?
Have you grounded your enclosure to the tower?
 
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nest
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Re: interference to two way radios

Sat Dec 10, 2011 6:28 pm

Is this possible at all
Very definitely, yes.
he's on 124Khz
Are you sure about that frequency? 124kHz is not a frequency used by any two way radio equipment I know of? That is a frequency for worldwide communication, the wavelength is measured in kilometres! ;-)

The interference could be coming from a number of different sources. As indicated above, it could be the Power Supply (when under load), the Mikrotik board or the wireless cards. You have to remove or swap out (with something completely different) to test. So, to test the PSU, as suggested work from just a charged battery only. No mains, no solar panels, no electronics controlling this. Just a normal battery directly into the Routerboard.

Then, consider removing the wireless cards and pigtails - just leaving the Routerboard only.

Then change the routerboard for a completely different model. (We found for example that all our RB532A's used to wipe out a VHF service across the whole island, we tried everything, checking earthing, adding ferrite blocks, but the VHF signal was being passed up through from the Routerboard, through into the R52 cards and then into the 2.4GHz aerial via the coax on the mast! In the end, changing to RB433's solved the problem even though we used the same wireless cards, outdoor boxes, coax, aerial etc. All we changed was the Routerboard.)

If the interference heard on his radios is a hiss sound - this suggests a switched mode power supply. If it were more pulsed and harsh a sound, I would suspect the 5.8GHz RF side. You can prove this by changing the RF mode of the wireless card between 802.11 and nv2 as they will sound different. Also you can disable the wireless cards in winbox and see if the interference sound changes. If it is the RF the interference should stop and start as you enable/disable the card.

Ron

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