The
312B-4 Control Console is a common component starting with
the S1 stations through the S3 stations. This device provided
directional Wattmeter and SWR (Standing Wave Ratio) functions
on the HF frequencies. Additionally the 312B-4 provided the
phone patch capabilities for the station. Back then the Bell
companies required you to have a DAA (data access arrangement)
to connect the 312B-4 to the telephone line. The antenna relay
assembly is shown to the right and can also be seen in the
rear view of the 312B-4 (above right). The watt meter and
SWR transducer is located in the assembly. Typically if you
have problems with the 312B-4 it will be the diodes located
in this assembly.
