[Milsurplus] Re: BC-709 amplifier

[David Stinson]

Used in Ferrying operations.
Aircraft were often delivered without radios or other comm
electronics, because the Air Corps learned early on that
what was used at a given destination wasn't always "by the book,"
forcing whole units to remove and replace radios before
they could use the aircraft and, usually, wasting the 
pulled-out equipment.  Ferry pilots were issued battery-
operated radios and, if the radio didn't have provision 
to double as an intercom to the co-pilot (many of them did),
a battery-operated intercom amp.  Yes; I have documentation.
73 Dave S.