senao txpower

[Gudmundur Karlsson]

I have a Senao 2511 CD PLUS EXT2 with a 5 dBi Omni RP-TNC antenna running in
Master mode.  iwconfig shown below.

I still don't seem to get good range.  It seems the same as any other card
I've used.
How do I check if the card is really transmitting at 200mW ?
If it isn't, then how do I set the txpower?

iwconfig won't set it with iwconfig wlan0 txpower 200mW:
Error for wireless request "Set Tx Power" (8B26) :
    SET failed on device wlan0 ; Operation not supported.

gct3102:/etc/rc2.d# iwconfig wlan0
wlan0     IEEE 802.11b  ESSID:"gcwl"  Nickname:"gct3102"
          Mode:Master  Frequency:2.422 GHz  Access Point: 00:02:6F:09:B1:41
          Bit Rate:11 Mb/s   Sensitivity=1/3
          Retry min limit:8   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality:0  Signal level:0  Noise level:0
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:635  Invalid misc:3525   Missed beacon:0

Thanks in advance,
Gudmundur