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166 Appendix E

Caring for Connectors

Mechanical Specifications

The critical dimension to be measured, regardless of connector type, is

the position (generally, the recession or setback) of the center conductor

relative to the outer conductor mating plane.

Mechanical specifications for connectors specify a maximum distance

and a minimum distance that the center conductor can be positioned

behind (or, in female Type-N connectors, in front of) the outer conductor

mating plane. Nominal specifications for each connector type exist, but

the allowable tolerances (and sometimes the dimensions themselves)

differ from manufacturer to manufacturer and from device to device.

Therefore, before gaging any connector, consult the mechanical

specifications provided with the connector or the device itself.

Precision 7mm Connectors

In precision 7mm connectors, contact between the center conductors is

made by spring-loaded contacts called collets. These protrude slightly in

front of the outer conductor mating plane when the connectors are apart.

When the connection is tightened, the collets are compressed into the

same plane as the outer conductors.

For this reason, two mechanical specifications are generally given for

precision 7mm connectors: the maximum recession of the center

conductor behind the outer conductor mating plane with the center

conductor collet removed; and a minimum and maximum allowable

protrusion of the center conductor collet in front of the outer conductor

mating plane with the collet in place.

The center conductor collet should also spring back immediately when

pressed with a blunt plastic rod or with the rounded plastic handle of the

collet removing tool. Never use a pencil or your finger for this purpose.

With the center conductor collet removed, no protrusion of the center

conductor in front of the outer conductor mating plane is allowable, and

sometimes a minimum recession is required. Consult the mechanical

specifications provided with the connector or the device itself.

Keysight NFA Series User Manual

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