ae) Printed Circuit Boards (PCBs)
The HW and SB series transceivers used a (mostly) common set of printed circuit
boards. Because of the similarity among different levels, it is possible that different
versions of the same board may have been used during production (i.e., earlier
production runs may have used on version of a given board while later production runs
may have use a different version, or even two different versions). While unlikely, it is
also possible that a given board may have been replaced with a different version as a
repair.
Printed Circuit Boards (PCBs) Page 107