Hello,
in a nutshell:
root@tplink:~# uci show wireless.radio1
wireless.radio1=wifi-device
wireless.radio1.type='mac80211'
wireless.radio1.hwmode='11a'
wireless.radio1.path='pci0000:00/0000:00:00.0'
wireless.radio1.txpower='19'
wireless.radio1.country='CZ'
wireless.radio1.cell_density='0'
wireless.radio1.channel='48'
wireless.radio1.htmode='HT20'
root@tplink:~# iwinfo wlan1 info | grep Tx-Power
Tx-Power: 12 dBm Link Quality: 59/70
Why just 12?