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HP 85027A/B/C Service
CAUTION: SMA CONNECTORS
SMA connectors will mate with precision 3.5mm connectors. But use caution to prevent
accidental damage due to worn or out-ot-specification connectors. Such connectors can
destroy a precision 3.5mm connector
even on the very first connection.
Hewlett-Packard
recommends that you keep two points in mind when you mate SMA with 3.5mm
connectors.
(1) SMA connectors are not precision mechanical devices. They are very susceptible to
mechanical wear and are often found to be out of specification prior to first use. Thus
gaging SMA connectors is the single most important step you can take to prevent
damaging your equipment. It takes very little time as shown in Section 8.
Also take care with initial alignment: push the two connectors straight together without
overtightening or rotating either center conductor. Use a torque wrench (HP part
number 8710-1582) for the final connection. This torque (5 lb-in, 60 N-cm) is less than is
used when mating 3.5mm connectors together. Use connector-savers for an extra margin
of safety.
(2) Important structural and dimensional differences exist between these two types of
connectors. Thus when an SMA connector is mated to a precision 3.5mm connector, the
connection will typically exhibit a discontinuity match at about 20 GHz. This mismatch
is less than when two SMA connectors are mated together although it is higher than
when precision 3.5mm connectors are mated together.
PRECISION 3.5mm CONNECTOR
SMA CONNECTOR
Figure 8-4. SMA and Precision 3.5mm Connectors
8-10
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