Product Overview
Pomona 3839 Bayonet Dust Cover for BNC Female Receptacles
Condition
Unused new old stock (NOS). Package labeled ITT Pomona Electronics Model No. 3839, Quantity 1, Dust Cap, BNC(F). Markings stamped on collar: POMONA 3839.
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Product Overview
Machined brass protective cover designed to mate with standard BNC jacks and chassis receptacles. Built with a knurled outer bayonet coupling, internal protective sealing gasket, and an attached tether lanyard, it guards sensitive RF inputs against bench debris, physical impacts, and environmental contaminants when test cables are disconnected.
Key Features
- Mates with all standard 50-ohm and 75-ohm BNC female jacks and bulkheads
- Machined brass body with tarnish-resistant finish
- Non-shorting mechanical design keeps signal pins isolated
- Internal silicone rubber gasket seals the mating interface
- Attached metal bead chain lanyard anchors to front panels or chassis mounting hardware
- Standard quarter-turn bayonet twist-lock action
Applications
- Capping unused RF ports on bench oscilloscopes, spectrum analyzers, and signal generators to keep dust out of input circuits
- Securing female BNC bulkheads on broadcast racks, patch bays, and CCTV distribution boxes between cable runs
- Makers building custom test jigs or field enclosures who need a tethered protective cover for chassis-mounted BNC connectors
Frequently Asked Questions
Does this cap short the center pin to ground?
No. The 3839 is a non-shorting mechanical protective cover. It does not contact or ground the female center socket.
What type of connector does this cap mate with?
It mates directly with standard female BNC receptacles, panel jacks, and bulkhead adapters.
How does the tether attach to an instrument panel?
The bead chain lanyard slips under an adjacent front-panel mounting screw, chassis ground screw, or jack retaining nut to keep the cover captive when uncoupled.
Nothing ruins a sensitive RF input faster than shop grime settling into an open jack. Anchor the tether, twist the bayonet home, and keep your bench gear clean until the next measurement.
