[Elecraft] K3 Diversity Receive is too quiet

[Steve]

My receive antenna, when plugged into ANT 1, produces much louder signals 
and much less noise than plugged into AUX RF/BNC during diversity receive.
    I am unable to locate anyone addressing this issue in the past 3 years 
of archives.
    The K3 does have a sub receiver, but, no antenna tuner.
The sub receiver and main are set for:
 PRE is on
ATT is off
AF is turned up
RF is full on
L-MIX-R appears to be unavailable during diversity.
Tuned in signals are heard, but they are very weak when the receive antenna 
is plugged into AUX RF/BNC during diversity receive compared to the receive 
antenna being plugged into ANT 1.

Steve, NU7T