I've been experimenting with an external 6 dB antenna on the RB751U. I've observed strange behaviour. The documentaion states that to utilize the external antenna on channel 1, you need to set Antenna Mode to "antenna b".
I have configured a second RB751U to act as a client for my testing. I have the external antenna installed on the RB751U that is acting as the AP. With the RB751U client I'm able see both the Tx and Rx signal strengths on both ends of the link. As expected the Tx level on the client end matches the Rx level on the AP end and vice versa.
What is not expected is that when I switch the Antenna Mode from "antenna a" to "antenna b" only the Rx signal level on the AP (or the Tx signal level on the client) improves. In my case the signal level improves from about -30 to -20. (Obviously my client is close to the AP for this test.) The Tx level on the AP (Rx on the client) remains unchanged. When I switch back to "antenna a" both the Rx & Tx levels go back to about -30.
This test implies that the Antenna Mode is only switching the radio receiver over to the external antenna, not the radio transmitter. Is this a bug? It is documented anywhere? Why would this be true?
Can any comment on or confirm my observations?
I'm using version 5.11, RB FW version 2.37.