(cross-posted at the "parachute" thread, sorry for thread drift):
AE tried to use her DF on approach to Howland, according to the radio log. She said she could not get a minimum, meaning she could not determine what direction the signal was coming from. This also tells us the DF loop and receiver worked well enough to receive, if not capable of telling direction on 7500, the frequency she was listening to from Itasca at that moment. The unsuccessful Lae test was on 6540, which was also too high. She obviously didn't understand the loop's frequency limitation.
I think it is important to keep in mind that she could only receive on one frequency at a time, and that it took some time to change frequencies. When she reports that she hears Itasca, she's transmitting on 3105, and listening on 7500.
Had she switched her transmitter to 500, Itasca might have been able to get a DF bearing. She could transmit on 500, 3105 and 6210.