SMA connector construction/anatomy and materials

[matthuszagh]

I'm looking at Huber+Suhner cable-mount SMA connectors and there are a number of different options (for the same cable) that use different materials and differ in price. I'd like to understand the parts of the connector that each anatomical description refers to as well as the tradeoffs of using different materials (and platings) for each of these parts (I'm just interested in the metal materials, not the dielectric).

For reference, I'm including a cross-sectional picture of mated SMA connectors, labelled according to the parts I think I know.

I'll additionally be referencing the following connector datasheets (in order of ascending cost on Mouser, from about 9USD to 13USD):

- https://www.mouser.com/datasheet/2/829/HUBER_2bSUHNER_11_SMA_50_3_56199_NH_DataSheet-2582581.pdf
- https://www.mouser.com/datasheet/2/829/HUBER_2bSUHNER_11_SMA_50_3_46133_NE_DataSheet-2581951.pdf
- https://www.mouser.com/datasheet/2/829/HUBER_2bSUHNER_11_SMA_50_3_6111_NH_DataSheet-2582519.pdf
- https://www.mouser.com/datasheet/2/829/HUBER_2bSUHNER_11_SMA_50_3_56199_NE_DataSheet-2582056.pdf
- https://www.mouser.com/datasheet/2/829/HUBER_2bSUHNER_11_SMA_50_3_6111_NE_DataSheet-2581919.pdf

The datasheets reference:

- center contact (labelled 1)
- outer contact (labelled 3)
- coupling nut (labelled 2)
- insulator/dielectric (labelled 4)
- crimp ferrule (crimped part shown in the other image)
- body (??)
- gasket (??)

What are the body and gasket? Where are these in my images?

Now onto materials.

I've heard that Copper Beryllium Alloy is a high-quality contact material. I've also heard that higher quality SMA connectors tend to use stainless steel over brass (and that SS should be torqued to 8in-lb vs 5in-lb for brass). Is that true? I expect this was in reference to the coupling nut, but I don't know.

Some of the lower cost connectors I linked use stainless steel for the outer contact (inner contact uses beryllium copper). Wouldn't SS be a horrible material for the outer contact? I would imagine that needs good electrical conductivity. By contrast, some of the more expensive ones use gold-plated brass for the coupling nut. That would seem to contradict my preconceptions above. I would have expected something like beryllium copper for the center and outer contacts and SS for the coupling.

Does the conductivity of the of the coupling nut matter? I had thought the current return path was through the outer contact, not the coupling nut.