The IFBR1 was upgraded to the IFBR1a-VHF receiver
by adding a number of important and useful features:
(1) Two rotary HEX switches to manually set the operating
frequency, (2) Automatic sensing/control of a mono
phone plug to eliminate the mono/binaural switch, and
(3) A multi-color LED for battery status. The Frequency
scan and memory features were retained.