Attached is a copy of the RAS schematic. This is one that I put together being for some weird reason everyone I have come across was poor quality or split on two or three pages. Couple of fun facts! The RF gain control is always in the circuit, regardless of AVC condition. With the exception of AVC first RF amplifier always runs wide open. B- is isolated by two 1K resistors above ground and used to provide a negative voltage for the AVC bus controlled by the tube between the BFO and Power supply and have no idea why they went thru a lot of trouble to provide a 600 Ohm output on the headphones but used the “Old School” approach of extending the plate and B+ to an external transformer located on the speaker panel? And unlike every other military receiver no provision for feeding audio out thru a 600 Ohm line.

There is a terminal that extend the B+ switch to the outside world that’s used as a send receive switch. I have an external relay on my ARC-5 transmitter as part of the transmit receive function for the transmitter that controls that point but it results in the receiver B+ switch always being in the off position.

Ray F/KA3EKH