[Elecraft] K3S Sub-Rx Antenna Choices

[Lane]

In my quest to learn more about sub-rx operations, I’m reading through the
KRX3 antenna choices (KE7X book) and see that when installing the sub-rx,
there’s a choice to make in the connection of the antenna by connecting the
TMP cable to one of two places. A) to the ATU, or B) the auxiliary RF BNC
antenna.

I like the idea of connecting to the ATU which appears to allow me to use
the same antenna as the main, or by a software setting, which allows for
whichever antenna is not used by main. But the auxiliary BNC seems to be
used more for diversity reception (and can work same way).

Can anyone clarify what's best in what situations? My use is, I would think
is general, I’m wanting to learn how to operate w/ a sub. I’m guessing A is
the better choice. Which way does the factory ship the K3S?

Thanks.