QMA Snap-On Bulkhead Jack for RG-402 Semi-Rigid
The QMA interface is the quick-connect snap-on variant of the SMA — same 50 Ohm impedance and 6 GHz frequency ceiling, but the snap-on coupling replaces the threaded nut for faster mating in dense panel layouts where a torque wrench is awkward. The kit ships as four pieces: the connector body, one contact, one lockwasher, and one nut, so you get the full bulkhead mount hardware in one bag.
RF Performance and Mechanical Limits
Rated at 50 Ohms nominal impedance with a maximum operating frequency of 6 GHz and an insertion loss of 0.25 dB — the loss figure tells you this is a low-insertion interface suited for the upper end of the cellular and ISM bands where every tenth of a dB counts. The voltage rating is 335 V, and the snap-on fastening type is rated for 100 mating cycles; that cycle count is typical for a QMA and reflects the trade-off: faster mate/demate than an SMA, but the snap-on collet wears sooner than a threaded nut.
This jack is built specifically for RG-402 (.141" semi-rigid) cable — the cable group is listed in the spec, so the centre conductor and dielectric dimensions are matched to the contact and body bore.