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jdub
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RB912UAG, negligible TX power

Fri Jan 10, 2014 3:53 pm

Got a bit of a problem with a new RB912UAG. I had it set up as an access point using the built-in radio, working fine, but now after taking it on a flight across the Atlantic none of my devices can see it any more (or they see it with worse than -90 dBm signal strength). I've tried a reset, and the AP is active with normal transmit power. I've also checked the pigtails and scanning the neighboring environment shows both weak and strong signals, so I assume the RF hardware is functional.

Any suggestions for things I can test, ways of debugging this?

Only thing I can think of is that the power adapter, an EU model and I'm now it the US, is not giving the AP enough power despite the adapter being rated for 100-240V. Don't have another I can test with yet, however.

That, or somehow just both TX chains broke... :shock:

Cheers,
Jw
 
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normis
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Re: RB912UAG, negligible TX power

Fri Jan 10, 2014 3:57 pm

post config from the device with this command "/export compact" and we will see if the configuration is OK. Then we can start looking at other things.
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jdub
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Re: RB912UAG, negligible TX power

Fri Jan 10, 2014 5:26 pm

Attached is the config. I assume you don't mind that I took out the WPA2 key.

- Jw
[root@Notus] > /export compact
# jan/02/1970 00:09:58 by RouterOS 5.26
# software id = 9YTT-PK5A
#
/interface bridge
add l2mtu=1600 name=bridge
/interface wireless
set 0 band=2ghz-b/g/n bridge-mode=disabled channel-width=20/40mhz-ht-above country="united states" disabled=no distance=indoors frequency=\
    2437 ht-rxchains=0,1 ht-txchains=0,1 l2mtu=2290 mode=ap-bridge name=wifi-builtin ssid=NOTUS wireless-protocol=802.11
/interface ethernet
set 0 name=gigabit
/interface wireless security-profiles
set [ find default=yes ] authentication-types=wpa2-psk mode=dynamic-keys supplicant-identity=MikroTik
/ip dhcp-server
add interface=wifi-builtin name=dhcp1
/ip hotspot user profile
set [ find default=yes ] idle-timeout=none keepalive-timeout=2m
/ip pool
add name=default-dhcp ranges=192.168.88.10-192.168.88.254
/ip dhcp-server
add address-pool=default-dhcp interface=gigabit name=default
/interface bridge port
add bridge=bridge interface=gigabit
add bridge=bridge interface=wifi-builtin
/ip address
add address=192.168.1.4/24 comment="default configuration" interface=gigabit
add address=192.168.1.4/24 interface=wifi-builtin
/ip dhcp-client
add comment="default configuration" interface=wifi-builtin
/ip dhcp-server network
add address=192.168.88.0/24 comment="default configuration" dns-server=192.168.88.1 gateway=192.168.88.1
/ip dns
set allow-remote-requests=yes servers=192.168.1.1
/ip dns static
add address=192.168.88.1 name=router
/ip firewall filter
add chain=input comment="default configuration" protocol=icmp
add chain=input comment="default configuration" connection-state=established
add chain=input comment="default configuration" connection-state=related
add action=drop chain=input comment="default configuration" in-interface=wifi-builtin
add chain=forward comment="default configuration" connection-state=established
add chain=forward comment="default configuration" connection-state=related
add action=drop chain=forward comment="default configuration" connection-state=invalid
/ip firewall nat
add action=masquerade chain=srcnat comment="default configuration" disabled=yes out-interface=wifi-builtin
/ip neighbor discovery
set wifi-builtin disabled=yes
/ip route
add distance=1 gateway=192.168.1.1
/system identity
set name=Notus
/system leds
set 0 interface=wifi-builtin
/system routerboard settings
set cpu-frequency=600MHz
/tool mac-server
add disabled=no interface=gigabit
/tool mac-server mac-winbox
set [ find default=yes ] disabled=yes
add interface=gigabit
 
jdub
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Re: RB912UAG, negligible TX power

Fri Jan 10, 2014 7:24 pm

I've done a bit of further experimenting, and there clearly seems to be something wrong with the TX hardware.

My smartphone detects the NOTUS ssid when held almost against the antennas. A wifi analyzer app then gives a signal strength around -90 dBm, just enough to connect to, get an IP and access my local network as normal. The WebFig interface then reports one connected device, with an extremely high signal strength of -22 dBm. Moving it just half a meter away causes the phone to lose its connection and lose sight of NOTUS.

Would it help debugging to play around with which chains are in use for TX? I assume disconnecting the antennas is inadvisable, based on the warning label stuck on the board when I received it.
 
jdub
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Re: RB912UAG, negligible TX power

Tue Jan 14, 2014 9:38 pm

My suspicion that it was the power adapter seems to have been correct. The EU adapter I had specifically says "INPUT: 100-240Vac 50/60 Hz", but I did notice that the start-up beep was weak. Just received a new US adapter and now I'm getting full signal strength. :D

Bizarre. I'll test the EU adapter when I next get a hold of a multimeter.
 
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normis
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Re: RB912UAG, negligible TX power

Wed Jan 15, 2014 9:32 am

My suspicion that it was the power adapter seems to have been correct. The EU adapter I had specifically says "INPUT: 100-240Vac 50/60 Hz", but I did notice that the start-up beep was weak. Just received a new US adapter and now I'm getting full signal strength. :D

Bizarre. I'll test the EU adapter when I next get a hold of a multimeter.
Please do, and report your findings to support@mikrotik.com
Most likely this is a single defective unit, as the specifications of the adapter are suited for use in the US
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boliveira
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Re: RB912UAG, negligible TX power

Thu Jul 17, 2014 7:43 pm

Hi,

I am having the same issue, but i already replaced the power supply and reseted all the configuration with no change.

I can see the SSID only if i get my device close to the routerboard. I think it is a hardware problem.

Kind regards,
Bruno
 
jdub
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Re: RB912UAG, negligible TX power

Thu Jul 17, 2014 7:49 pm

Hi,

I am having the same issue, but i already replaced the power supply and reseted all the configuration with no change.

I can see the SSID only if i get my device close to the routerboard. I think it is a hardware problem.

Kind regards,
Bruno
Yeah, I'm not entirely sure it was the supply, as I think it happened once more. I get the impression it has to do with movement, and haven't had a problem after mounting it to a wall.

- Jw

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