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el berto
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Burn device or bug (or wrong configuration)?

Mon May 16, 2011 1:57 pm

Hi, I'm using a RB433 with two ATHEROS AR5213 cards (working at 5 GHz).
I had a link with remote AP, during test I was using 14 dB as TX power.
For error I set TX power to "default", so I've seen 19 dB into bottom box "Current Tx Power".
I was surprised I could reach 19 dB, but my real problem was I lost link to remote radio; then restore the "all rates fixed" mode with 14 dB tx power.
I've thought there could be a problem in the remote device, but through snooper I could see it (about -90 dB signal strength), but no registration.
I said "the PCI radio is out", so I put the antenna on WLAN2: same problem where I can see the radio through snooper, but no registration.
I also changed antenna, but the same.
If I've broken the PCI radio, I can't have broken all two radios (WLAN2 was still unused before).
I tried to change the radio (new RB433, new AR5213 modules) and set the same configuration through export command: now I have the link and the remote radio is registered at -75 dB.
What's wrong, have I really damaged RB433 or pci radio?
Thanks.
 
SurferTim
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Re: Burn device or bug (or wrong configuration)?

Mon May 16, 2011 2:05 pm

What make and model is the radio? If the radio has a maximum power of 19db at 6M, then it could have smoked the radio. It is hard to tell without the spec sheet on the radio to tell what the maximum power is at 54M tx rate. That tx-power is normally lower.

ADD: If that radio was a R52, then it is probably smoked. 14db is 1db too high for 54M tx-rate.
 
el berto
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Re: Burn device or bug (or wrong configuration)?

Mon May 16, 2011 6:02 pm

But I think the RouterOs should set the maximum power depending the data rate and the radio module model....

From Wiki:
What TX-power values can I use?

The tx-power default setting is the maximum tx-power that the card can use and is taken from the cards eeprom. If you want to use larger tx-power values, you are able to set them, but do it at your own risk, as it will probably damage your card eventually! Usually, one should use this parameter only to reduce the tx-power.

In general tx-power controlling properties should be left at the default settings. Changing the default setting may help with some cards in some situations, but without testing, the most common result is degradation of range and throughput. Some of the problems that may occur are:

* overheating of the power amplifier chip and the card which will cause lower efficiency and more data errors;
* overdriving the amplifier which will cause more data errors;
* excessive power usage for the card and this may overload the 3.3V power supply of the board that the card is located on resulting in voltage drop and reboot or excessive temperatures for the board.
So the RouterBoard will reboot in the worst case, but not break.....
 
SurferTim
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Re: Burn device or bug (or wrong configuration)?

Mon May 16, 2011 6:08 pm

If you set the wireless "tx-power-mode=all-rates-fixed", then all bets are off with the RouterOS. It will set whatever power you want. Trust me. I burned out a R52 thinking it was a R52H. tx-power=22 would be good for the R52H. The R52 did not survive.

ADD: What I mean by "not survive" is the wireless card was accessible from the router and everything looked normal, but nothing came out. No ssid, even up close. :( Would you consider "burned out" as "lower efficiency" or "more data errors"?

Mikrotik recommends "Don't mess with these settings".

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