JB64T — 64-Channel BNC Junction Box, Tender Configuration

JB64T is the family’s chassis-configured build, engineered to a customer tender specification for a 64-channel BNC junction box for precision signal routing in vibration measurement, acoustic testing, modal analysis and structural health monitoring. Where every other model in this family ships in the standard screw-fixed T-series construction, JB64T is built the other way: a rigid rectangular chassis in cold-rolled or mild steel, minimum 2 mm thickness, powder-coated black by default, edges deburred and chamfered, supplied with a vertical castor-wheel stand for floor mobility.

Panel and cover

The top cover carries 64 BNC connectors grouped into 4 zones of 16 channels, with zone labels or dividing graphics separating the groups. Port numbering is printed on both the outer and inner face of the cover, in a font sized and contrasted to stay readable under typical field lighting — with the lid open or closed, a technician can read the channel map.

The cover itself is hinged, with a heavy-duty cabinet-grade folding lid-support stay that holds it open without a hand on it, and a lockable closure — key-operated or hasp-type — with ergonomic handles at both ends for two-point operation.

Cable management

Four cable glands, one positioned adjacent to each zone to minimise internal cable crossings, each sized for a bundle of 16 coaxial cables. Gland material is nylon or nickel-plated brass.

Electrical specification

±0.1 dB flatness, 10 Hz–20 kHz is the specification that defines this box. It is the number that determines whether the assembly is transparent to the measurement passing through it, and it is verified by measurement on every unit.

Parameter	Requirement	Expression
Flatness	±0.1 dB, 10 Hz – 20 kHz	Measured across the full usable band
Total harmonic distortion	≤ 0.001%	≤ −100 dBV ref. fundamental @ 1 kHz
Noise floor (broadband, A-weighted)	≤ −120 dBV	≤ 1 µV RMS, 50 Ω termination
Contact resistance	≤ 5 mΩ	—
Insulation resistance	≥ 1000 MΩ	—

JB64T is a passive assembly: 64 connectors and coaxial runs, with no active device anywhere in the signal path to generate distortion or noise of its own. The THD and noise-floor figures above are null-result measurements — they characterise the calibrated test system at least as much as the box, and what they demonstrate is that the assembly adds no detectable distortion or noise above the analyser’s own floor. Read them as confirmation, not as a spec the box “achieves” the way an active instrument would.

Two points worth carrying into a tender response:

• The tender’s 50 Ω / DC–4 GHz connector rating sits well outside this box’s 10 Hz–20 kHz usable band. An IEPE accelerometer chain is not an impedance-matched RF line at audio frequencies, so 50 Ω vs 75 Ω makes no measurable difference here — the requirement is harmless but narrows the approved-connector list.
• Delrin (Acetal/POM) is specified as the insulator; PTFE and polyethylene are explicitly not accepted. PTFE has a marginally better dielectric at RF, but for this band the difference is not measurable, and Delrin is standard and less costly. Worth confirming with the customer if PTFE is a fixed BOM requirement rather than a technical one.

Test report

Generated on a calibrated audio/RF analyser, covering a minimum of 10% of connectors or 8 channels — whichever is higher — with worst-case values reported. Values are given in both dBV and percent where applicable, and the report is submitted with the unit, not after delivery.

Tender compliance checklist

Reproduced from the customer specification, for direct mapping in a tender response.

• Exactly 64 BNC female-to-female bulkhead adaptors, 50 Ω, Delrin insulator, nickel-plated contact
• Connector make from approved list only (Amphenol / Neutrik / TE Connectivity / Fairview Microwave)
• Port numbering on inside AND outside of top cover
• 4-zone × 16-channel grouping with 4 dedicated cable glands
• Lockable cover with handles and soft-close lid support arm
• Powder-coated steel chassis
• Test report for THD, noise floor and frequency response (10 Hz–20 kHz) in dBV and %

Typical applications

• Aircraft-structure vibration and modal testing
• Large modal test arrays and impact/shaker campaigns
• Acoustic and microphone-array measurement chains
• Structural health monitoring (SHM) installations
• End-of-line test benches with a fixed, repeated sensor layout

See current pricing and configuration options on the TIERA store.

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Pairs with:

• Junction Box family — full line-up, configuration matrix and electrical spec
• JB48T · JB80T — neighbouring channel counts
• PhonoVibe Series — multi-channel DAQ to receive the routed channels