Problem with ht-txchain 1

RouterOS General
1

I have strange problems with version 5.0RC(X). Chain-0 is working good, but when I connect antenna to Chain-1, there is very poor signal.
Here is one image from my dual link. I have water issues on chain-0, so I tried to remove it and leave only chain-1 to work. I disabled chain-0 on both sides, but there was no connection. I tried all combinations but with no success. When I enable only chain-0, which have very poor signal, then link manage to connect. What’s wrong with using only chain-1.
This sample is not only one in my network. When I moved pigtails from chain-1 to chain-0 (single antenna on both sides) signal and CCQ improved and link was usable. When link was connected to chain-1, signal was 30% lower and troughput was about 1Mb (megabit), and CCQ was terrible.

Is there a difference in using cahin-0 or chain-1???

All cards are R52N-M or R52Hn. On this dual link, which is on picture, cards are R52Hn and I’m using dual polarity antennas.

2

I’ve seen strange behavior of chains, too. I did not manage to detect the rules
until now. Some links run best with one chain enabled on one side and two on
the other side. I have a link where running on chain two on both sides does not
work at all. Running on chain one does work with bad signal. Enabling rx of chain 1 on
one side gives a good link. So chains do not work independent of each other.

Newest rc gives rx/tx numbers for each chain. I have to look into this links again.

3

you can check this as usual wireless link, each chain seperately, and then check how they work together if 11n is enabled. Most probably, there is some interference or hardware is damaged (connectors, cables)

4

This is reply from MT support:

Hello,
chain-1 is optional chain and the link can’t work without chain-0. You always need
to be using the chain0 if you want to use chain-1 as well. Note that you should
always have antenna connected to the antenna port(chain) if you do not want to
damage the power amplifier of the wireless card.

So, if I use N standard with only one antenna, then I MUST use chain-0? But on A/B/G standards, I can chose which one to use?

5

you have to use chain-0 RX at all times, chain-1 is optional

6

Ok. Thx for info.

7

So can we expect a warning on the radios now? We’ve now just blown around 6-8 cards because of this. Not cool MT

8

So connected chain-0 and using chain-1 alone does not work/gives bad signal?

Not connecting chain-0 would damage the card even when only RX at chain-0?

Using a V+H Antenna connected chain-0=V-Pol chain-1=H-Pol I cant operate
at H-Pol only. I get interference from V-Pol as I have to use chain-0 RX ?

9

If you have connected both chain0 and chain1 to antennas and want to use chain1 then you need to enable the chain0 as well or the chain1 will not work correctly (bad signal, no connection).
if you have enabled chain-0 and don’t have connected any antenna you could damage the power amp.

In your case you should use chain-0 to RX and the chain-1 to Tx/RX or just switch the antenna connectors to have H-pol to chain0.

10

Thanks. This is very new information which clarifies some strange behavior in the past.
You should integrate this into the manual as it is not the expected bahavior.

11

I had the same problem.
Last night, after 532A upgrade goes bad, for a rapid sobstitution i change it with 411+r52n, but i connected the wrong chain (the only one i can reached with pigtale) and the link was unstable until the next morning when we changed all the device.
Not a great expirience with -6°C. :confused:

12

How about changing RouterOS so there are not checkboxes for Chain 0.

13

Is enought to connect to not used port only pigtail? to prevent damage power amp? or it must be antenna?