HAM radio interference from RB-s

RouterOS Wireless Networking
1

I searched all threads but I have not found anything similarly for Mikrotik product.
On one tower where is our base station is 28Mhz (10 m) HAM radio antenna, and our RB 433UAH and RB711 5hn. colleagues report that 28Mhz band is out of use because of noise produced from our RB-s.
When I power off RB-s it’s OK.

I can see that it is 20 kHz step noise all over the band.
RB 433 and RB711 is connected with ethernet with 2m of STP cat 5e cable. PoE 24V DC from battery.

The boards is in plastic box.

I try change boards, check cables, grounding…

This is our new basestation and the first nearly HAM radio antenna?

Any suggestion, experience, solution?

2

Never ran into this.

Try disabling just the radios on your RB’s to determine if it’s rf from the radios that is interfering with ham.

Get metal enclosures. You can interfere with your equipment with plastic enclosures.
If you can’t replace the plastic enclosures, at least line them with a metal foil tape.

3

I’ve got one customer that is a HAM that has issues, might be at 28MHz.

I’ll ask again for clarification.

I haven’t had much luck, but different voltage POE introduce different interference, always on the same band though.

4

How i see the most interference come from ETHERNET. Even we use SFTP cat 6 cable, RB without metal case it is bad.
Therefore: metal case for RB, god SFTP cable, god grounding, and quality power sup… or run away from HAM towers :wink:

When i put RB711 in metal case the situation is better, but not enough.

I will update this topic when install metal case on other (RB433 uah) router, and test.

EDIT
at such locations, it is best to forget use some solutions like sextant, sxt, omnitik… because plastic case :frowning:

5

After placing RB433 in metal case the situation is only slightly bether.

Everything is OK until plug ethernet connection between two routers :-/
It is Ubiquiti Tough Cable Level 2, shilded with orginal shilded connectors…

6

mm


About the frequency as an smps.

So what is keeping up the charge across the battery? Not an smps?

7

As a ham operator I have a similar issue, but with an ubiquity rocket 5.
The culprit is the ethernet cable: If set to 100 Mbps I have heavy interferences on 28 MHz and 145 MHz.
Switching to 10 Mbps solves a big part of the problem, but not completely.
The only way to solve this is to get at least 3m between the radio antenna and the cable/device, but this means two towers…
So much about Class B digital device part 15 of the FCC rules.

LE: Strangely I don’t have this issue with a Nanostation 2 in the same spot… Could it be related to the ethernet chipset?

8

This is another problem that we solved with RF choke (ferrite) on solar charger output, and that smps is away from tower with ham antenna.
Interference on ethernet I cant stop, trying everything just slightly reduced it but they are still there.

9

Just a little comment:
The effort for solving these issues is really necessary.
Ham radio operators are primary users on the 28MHz and 144 MHz bands. This means that they benefit from interference protection enforced by the authorities. So they can easily and officially ban your equipment from the tower (as long as it is not your own tower - case in which you can make them move)…

10

I am a HAM too, I used to have all my equipment at the top of my 12M tower, just under my rotator for my 50Mhz beam.

Also connected to the tower was HF wire antennas.

I had NO rfi problems what so ever.

I made sure that I used a linear regulated 24V supply for the MT equipment and fed the whole lot via RG58 50ohm antenna cable.. The sheath was earthed to the tower legs at the bottom only.


PS, whoever it was that made the comment about CE approval of SMPS units.

I used to work in an EMC compliance lab, and the rules state that the unit only complies with the tests when the “standard” length of cable is used… I refer to the output lead often choked.

Once a longer lead is used, or extended, then the approval can no longer apply because the user has modified the unit by extending the lead.

11

Ok, but try choke ethernet communication between two routers on top of the tower.
I use best cat6 cabling, grounded, metal cases for RB-s grounded… Ethernet still interfere. every ethernet communication in 10 m from ham anthena is problem.

12

but you say that you supply the MT routers with battery power.

1: what is charging the battery?
2: You say you see 20khz noise, are you using scope to see that, its clear that the 20khz noise is from an smps.

Sollution

Feed the equipment on top of tower from a linear regulated supply, not a switcher.

Use a fibre optic link from base to top of tower, those converters are cheep these days, only 30 euro each end.

Simon

13

Interference from MPPT solar regulator I suspend with chocke-s, and ethernet interference is there all day and night.
When ethernet communication is established there are strong interference ( like this http://www.youtube.com/watch?v=fTu460Py-TI), without ethernet all clear.

I connect two RB’s on diferent tower sides (about 40 cm lan cable) with cat6, grounded, and chocked. When pluged out that connection all is OK.

Sou, eny solution for that?
I think, fiber is ok, but media conwerter also has ethernet!

14

Yes, but that one can be very short…
Borrow one and try :slight_smile:

15

I try connect two routers in one metal case, with les than 5cm SFTP cabel… šššbiiip šššš…biiiii…eeee…ššššš :wink: