Missing Stream on B5c - UK 15km Link


I’m having a nightmare of a time trying to increase throughput on a B5c link spanning just under 15km here in the UK (EIRP 36). I’m using L-Com 30dBi dishes that I have set up in x-polarity. I’m hoping somebody can point me in the right direction - screenshots below:

Many thanks in advance for any help you can offer. I have read in a similar post that it could be a defective radio?

Best regards,


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Hi @Paul13,

Could you provide us or me a screenshot of the full channel and power page?

Well, your chain 3 and 4 have no TX power, and your SNR is pretty low for your distance. Something seems off though. Have you tried smaller channels?

@William5 I suspect that the TX power for the second channel is set much lower than the TX power for the first.

Hopefully we’ll get a screenshot that’ll confirm or deny.

Hello Dustin and William,

Many thanks for your replies and I apologise for the delay getting back to you.

Originally, one channel was sent in UK Band C which allows an EIRP of 36 and the other in Band B with an EIRP of 30. As the dishes we’re using are 30 dBi gain, this meant the lower channel could only have a transmit power of 0!

As an experiment, I bent the rules slightly and said the dishes were of lower gain than they actually are in order to send out more power. I’ve also now set both channels to Band C and unfortunately, the problem persists. Please see below:

Thanks again folks - hopefully you can help me identify the problem!

Best wishes,


Streams usually drop off because of poor RF conditions or high error rate. What is your Rate Adaptation set to? This is found under the Link tab.

Thanks for the explanation. Makes sense.

Ya know, it almost looks like some of my Ubiquiti equipment when it gets water inside the casing, I have never really hunted down the problem, we just replace the equipment, but I have always suspected a bad connector from water getting where it is not supposed to go.

You might try swapping the cables around on your B5c and see if the lower Rx Power changes in the swap. Begin to isolate the issue to either the radio or the cabling/antenna. My guess is that Stream 4 is Chain 3’s stream and because you are dealing with an SNR of 9 its unable to hold much of a connection.

I have had the same problem on two B5’s, and it ended up being bad TX chain. Replaced under warranty and all OK after that.

Hello All,

Dustin - the Rate Adaptation Criteria is set to ‘PER’ and PHY Rate is ‘Aggressive’. According to the spectrum analyser we have a nice, relatively clean spectrum. Could there be something else going on or is it likely to be a problem with the radio?

William - Thanks for that input. It’s tricky messing around too much with this radio as we’ve now got a handful of customers utilising the link. I’ll have a think about how best we can test this.

Mats - That’s very useful to know. I wonder if I should draw Mimosa’s attention to this post and see if they will agree to send a replacement radio? At least for the purposes of process of elimination!

Best wishes,


Hi @Paul13,

You’ve already drawn Mimosa’s attention to this post! We would be more than happy to RMA this radio, if you have a moment to come to our chat and go through some troubleshooting with our Support guys. They are great at seeing what’s going on by looking at the support logs and using cloud data.

As for the chains, they look ok. Usually if you have a bad RF cable, the difference between the H and V would be huge. Try changing your PER Aggressive to PER Conserative and see if that improves you link. If it doesn’t, follow my above advice and come talk to us!