works as a Wi-Fi when the value of the transmitter power is set by default? the handbook says that: default means that the card will use the tx-power values ​​from the cards eeprom and will ignore the setting what is specified by the user in the tx-power field. but how do I know what value is in epprom?

it will use the maximum possible by that card. check card specifications datasheet to see what is the maximum.

txpower setting is only to decrease power. increasing above specified maximum will burn the card.

i.e. in 751, where there is a 1-Watt transmission, by default, will run a one watt?in practice, I don't watch. I'm switching the ADvanced mode, traveling and seeing the 30dBm other hardware that dot the radiation work more than it was by default.

I suspected that the default is 50 milivatt/17 dBm.

no it will run at 1W by default, depending on the datarate. from the datasheet:

802.11g:
30dBm @ 6Mbps
27dBm @ 54 Mbps

802.11n:
30dBm @ MCS0
26dBm @ MCS7

you can see that the txpower changes depending on the datarate.

While the focus will be on the worst connection?that is, if we have multiple attached devices that connect at speeds of 54Mbps, from your above transmitter will operate with power 500mW 27dBm/and if you see a device that connect to an access point and it will have a connection with the speed, power and 6Mbps access point would be 1 Watt?

and if that's the case, then the clients that were formerly connected to the access point will be better?

please be more specific what you want to know?
When the data is being transmitted to the client at 6mbps it uses 30db, when it sends data at 54mbps it uses 27db.

This means when the next customer to send data, power transmitter adjusts to each customer?