Navy DZ-2 DF
 

The WW 2 vintage Navy DZ-2 aircraft DF had a freq range of 15-70 Kc and
100-1750 Kc. What was the lower range used for? The loop had two windings, one
for the 15-70 Kc range and the other for 100-1750. What was transmitting on the
low band?