49
Interior view of the completed SP-II Control Unit
IX. Assembly of the RF Relay Unit
Preparation for Assembly: The RF relay enclosure shown below consists of two
interlocking aluminum pieces powder-coated with an extremely durable graphite-colored
finish. Unfortunately, the powder-coating process has an unavoidable overspray into the
interior of the enclosure. Before beginning assembly, therefore, the builder should use the
small strip of emory cloth provided with the hardware packs to sand the powder-coating
off all the screw holes on the
inside
of the top cover. Doing so will ensure good electrical
contact between the metal cover and the ten SO-239 coax jacks, and also between the
metal cover and the four threaded standoffs that secure the printed circuit board. It is a
good idea, but not strictly necessary, also to sand off the paint on the lip of the top cover,
where the black sheet metal screws secure the two parts of the enclosure together.
(1) Identify the top cover of the RF relay enclosure and mount ten SO-239 UHF coax
jacks to the inside surface, as shown below. Use two 4-40 x 5/16” machine screws, with
internal lockwashers and nuts on each of the SO-239 connectors. The lockwashers go
