RB411AH + R52H AP Power Issue vs. D-LINK DWL-2100AP

RouterOS Wireless Networking
1

Hi guys,
nice to meet you, this is my first post, I’m new to Mikrotik but not to wireless… I am running a WLAN composed by one AP and about 10 clients (all D-Link DWL-2100AP @ 23dbm) since 5 years without problems but now I decided to substitutute main AP with RB411AH + R52H board just to test this professional configuration and maybe get more power strength and troughput on clients.

New Mikrotik AP is now running ok @ 25 dbm but I’m VERY surprised because signals on the clients side are about 50% of before and I don’t really know why. I checked out configuration many times, tried to upgrade routersOS version 3.13 to 3.20, changed tx power configuration but I have ALWAYS SAME SIGNALS.

Do you have any tips? Do you think hardware in not working in the right way?

Thank you in advance! Mario

2

“changed tx power configuration”

Bad bad bad. Leave it at default, you probably blew the card.

3

Thanks for the answer…

but this is impossible, signals are the same since my first start-up, I’ve never putted a manual tx-power over 25dbm

here you are the snapshot of the actual configuration:

4

5

Have you tried changing from antenna a to b or vice versa?

6

Yep, I tried and strangely there is no big difference between antenna a and antenna b… this is another stranger behaviour…
what do you think ?

7

I would try another radio card. Personally I wouldn’t use the R52H - there have been many failure reports. Either use the R52 or if you need the power an XR2

8

You have either a bad pigtail, cable or antenna, card or cable. I have had nothing but good luck with R52H btw, but have only bought around 20.

9

http://forum.mikrotik.com/t/r52h-faillure-rate-continues/20246/1

10

Hi guys,

I just bought another r52h card and after a new test everything is going well… I will RMA the first one soon.

Thanks for your help, see you soon. Mario

11

Hi there, just to keep you informed about my adventure with MikroTik mini PCI board…

yesterday new r52h’s power falls down again to a minimum level and many clients are due to low signal of the AP!

I will ask to the shop to change both R52H with simple R52 and I will definetly NEVER buy another R52H.

That’s all. I will keep you informed about the rest.

12

Hi,

Did you change to R52 and try out your adventure into Mikrotik? :slight_smile:

— Hassan

13

I have issues with R52H, too.
There was a defect pigtail cable which broke while the device was running.
I stopped all WLAN transfer rapidly and changed the cable. After that the recieve power on the clients
is so low that you only can connect if you are about 2 meters near to the AP.
In another room the signal gets totally lost. The bitrates that madwifi driver shows are at all ~1mbit to 5.5mbit/s and below.
At first i thought the new pigtailcable is defect, too. But after trying another UFL based Antenna directly on the board also with bad power output, i think the R52H amplifier really ‘blew up’ in a seconds..

The problem is, i dont have another card to test if the old one is broken.
Obviously no distributor can help cause i use Linux, changed the txpower and had broken cables. ;-(

14

I had the same problem using both R52 and R52H cards. The SNR was realy low. And I found out the reason. This is awkward, but it’s really happening. When the madwifi driver detect two antennas connectors on the R52 cards, it sets automatically the diversity up. Now, if you have two antennas physically connected to the card, this is fine. Nevertheless, I guess the most of you is using only one antenna connected to the MAIN connector. In this case you should take the diversity off and specify which connector to use to receive and transmit. You can check if you are using diversity in this way:

cat /proc/sys/dev/wifi0/diversity

PS: wifi0 or whatever is your wireless card.
If this command returns 1, it means that the diversity is enabled.
Furthermore:

cat /proc/sys/dev/wifi0/txantenna

If this returns 0, it means you are using transmission diversity.
The point is that you will definitely want to disable transmitter diversity if you only have one antenna connected. Otherwise 50% of your broadcast and multicast packets (ARP, OSPF) will go out on the wrong antenna. Furthermore you are likely to blow up the card amplifier when trying to transmit out of the connector not attached to an antenna because of impedance issues.
Since I have only one antenna connected to the card (to the MAIN connector), I have taken off diversity and specified to use antenna 1 for both reception and transmission. This is what you gotta do (for wifi0):

    
    sysctl -w dev.wifi0.diversity=0
    sysctl -w dev.wifi0.txantenna=1
    sysctl -w dev.wifi0.rxantenna=1

To save these settings, add them to /etc/sysctl.conf.

PS: For the R52 and R52H antenna 1 correspond to the MAIN connector, while antenna 2 corresponds to the AUX one.

After having applied this, I could noticed a ~10dBm gain in reception when no obstacles are present between the two antennas and a 5dBm gain when obstacles are in the middle. I really suggest to everybody to turn diversity off because otherwise your antennas will try to transmit out of the not connected connector.

Antenna diversity is treated here on the madwifi website: http://madwifi-project.org/wiki/UserDocs/AntennaDiversity

Cheers,

Stefano