Although the FAR's do authorize the "manufacturer"
of the aircraft to conduct the tests, the builder of an amateur-built
aircraft does not meet the FAA's definition of a manufacturer.
The FAA, in Order 8130.2, defines a manufacturer as a Production
Approval Holder (PAH). Some examples of a PAH would be the
holder of a Production Certificate (PC), a Parts Manufacturing
Authority (PMA), and Technical Standards Order Authorization
(TSOA). According to the FAA, an amateur builder does not
fit this definition and, therefore cannot perform the transponder
and pitot/static tests on his/her homebuilt.
(Info obtained from the EAA website)