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complete mechanical system that
met the tough environmental
conditions of a jet-aircraft borne, radar test instrument.
Being a
low quantity, high quality, (best commercial practice) test
equipment project for a Navy test facility, this unit could be
designed with component costs as a secondary consideration. Also, it
was reasonable to use machined and lathed parts.
The instrument was designed
with tight size and shape constraints; high altitude and high/low
temperature requirements; and shock and vibration performance
requirements.
An RF/digital/power backplane
interconnect system was devised to allow high density packaging of
various electronic modules. This was possible through the use of coax
loaded card-edge connectors. Each of four RF modules was designed to
plug into the unit for ease of assembly and maintenance. These modules
were designed as machined aluminum housings.
Outline and mounting of three
printed circuit cards was established so these too could be plugged
into the backplane. These cards were secured with expanding
"wedge-locks" along their edges.
A forced air cooling system was
specified to work with the natural airflow in the instrument test pod
and to maintain acceptable component temperatures at high temp, and
low pressure. In addition, a resistance heating element was
incorporated for the high altitude, low temp, test flight environment.
Internal ribs supported a three
piece sheetmetal skin, providing a rugged housing.
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