Читать книгу Handbook of Microwave Component Measurements - Joel P. Dunsmore - Страница 43

The 7 mm connector has a couple of interesting attributes: the center pin has no slots but contains spring‐loaded center collets that protrude slightly from the mating surface, as shown in Figure 1.18.

Figure 1.18 A 7 mm connector.

When mated, the collet from each connector floats against each other, providing a good center contact. There is a slight gap in the slotless outer sleeve of the center pin. As with almost all RF connectors, the outer conductor forms the physical mating plane. On most connectors, there is a slip‐ring‐threaded sleeve surrounded by a coupling nut. To mate, the threaded sleeve is extended on one connector and retracted on the other. On the retracted connector, the coupling nut is extended to engage the other's sleeve and is tightened. Only one coupling nut should be tightened, although it is common but incorrect practice to tighten the other coupling nut. In fact, tightening both coupling nuts can result in the center pins pulling apart and a poorly matched contact. Occasionally, one sees parts that contain only a solid threaded outer conductor (serving the purpose of the threaded sleeve) and no coupling nut. These are more common on older test fixtures intended to mount directly the 7 mm connectors of network analyzer test sets.