HP 85027A/B/C Service
Mechanical Inspection
Gaging the
Precision 3.5mm Connector: Use a
precision 3.5mm connector gage to
check the mechanical dimensions of the connector. The tolerances are tight, but must be
met to ensure perfect mating between the connector surfaces. Perfect mating both
ensures a good electrical match and reduces the possibility of connector damage.
The recession of the center conductor is the critical dimension. The maximum allowable
recession of the center conductor is 0.003 in. (0.08mm). The minimum allowable
recession of the center conductor is 0.00 in. Any center conductor which protrudes
beyond the outer conductor mating plane is out of tolerance. it will permanently
damage any connector attached to it by buckling the female contact fingers. This
danrnge and the resultant electrical interference is often noticeable as a power hole of
several dB at about 22 0Hz.
Any center conductor which is recessed too far (>0.003 in.) behind the outer conductor
mating plane will cause poor electrical contact and high reflections.
Before using the connector gage to measure the connector, visually inspect the end of
the gage and the calibration block. Dirty or damaged gage facings can cause dirty or
damaged connectors. Refer to Figures 8-5 and 8-6 to see how to use and zero the gage.
Refer to Figure 8-7 to see how to measure precision 3.5mm connectors. Note that a plus
(+) reading on the gage indicates a recession. Thus center conductor readings must be
b0.000 and +0.003 in.
If you will be mating precision 3.5mm connectors with SMA connectors, please refer to
Figure 8-4, SMA and precision 3.5mm connectors.
8-9
