Between-Series Adapter: SMA Jack to SMB Fakra Jack
The Amphenol APH-FKJ-SMAJ is a between-series coaxial adapter that converts an SMA jack, female socket to an SMB Fakra jack, male pin. It's the part you reach for when a harness has an SMA bulkhead on one end and needs to terminate into an SMB Fakra interface — common in automotive telematics or antenna feed systems where the Fakra latch is preferred over a threaded SMA for quick disconnect.
50 Ohm, 4 GHz — What the Bandwidth Means
The 4 GHz ceiling covers L-band, S-band, and most of the C-band up to the lower 4 GHz ISM allocation — so it handles GNSS, Wi-Fi, and cellular bands through LTE. Above 4 GHz the adapter's internal geometry starts to introduce mismatch loss; if your signal runs at higher frequencies, you need a different adapter rated for that range.
Construction and Field Life
The body is machined brass with a nickel finish — nickel holds up better against corrosion than bare brass in humid or salt-spray environments, though it's not a marine-grade finish. That wide operating range means it can sit in an engine bay or a rooftop enclosure without the dielectric shifting phase or the plating fretting from thermal cycling.
SMA Threaded, SMB Fakra Snap-On — Two Locking Styles
The SMA end uses a threaded coupling nut. The SMB Fakra end uses a snap-on latch with a colored plastic housing (the Fakra keying code, typically A through Z). The threaded side stays put under vibration; the snap-on side is what you disconnect repeatedly during service without tools. If your application sees constant vibration on both sides, the snap-on Fakra latch can wear over time — the 500-cycle rating on the adapter is a practical limit before the retention force drops.