to support operation of the R-1/ARR-1 VHF (246 MHz) "ZB" Homing Adapter

Thanks Mike,  very interesting.   I read part of the manual from your site to understand more about the AN/ARR-1 and now I see why they needed a broadcast band receiver!    And since the BC-946 would replace the BC-453 on the rack it also makes sense for it to provide power for the homing adapter.

73, Bob W9RAN