[Milsurplus] Ideas on Japanese circuit ?

[Hubert Miller]

Another thing that puzzles me, that i am very open to ideas on: 
BFO switched on, gives B+ to BFO triode. AVC is does not look like, is ever shut off, but it is DAVC,
delayed AVC, by a bias voltage on detector. 
But, there's another switch, that shorts the BFO tuned circuit, which shorts B+ to an audio oscillator.
So the BFO is no longer working at IF, and instead an audio oscillator is running.
The output of the audio oscillator is injected into the first IF.
The BFO switch must be in ON position for this to be operational.
My first thought was, this sounds like the postwar Bendix MN-? receiver that used an audio BFO.
It didn't work out, and there was a modification sheet issued to install a normal IF frequency BFO.
Voice and MCW ( A2 ) sidetone are provided to the receiver headphone circuit by circuit wiring.
Is this a way of providing CW ( A1 ) sidetone ? 
I don't see that the receiver B+ is ever cut off, even during transmit. It looks like only the antenna is
switched. 
Any ideas welcomed.
-Hue Miller