Typically anything with a BNC connection is only rated to 1 GHz, ie. HP 355 attenuators. ?I have pushed a BNC cable to 1.5 GHz, but that is as far as I would go with it.
DigiKey lists BNC connector spec.
Specifications for BNC Connectors
BNC style connectors are miniature, light-weight, weatherproof interconnecting devices characterized by their two-stud, quick disconnect bayonet lock coupling arrangement. Their design functions satisfactorily from DC to 11 GHz in static applications, or from DC to 4GHz in applications involving vibration. The connectors typically yield a low VSWR (reflected signal) to 4GHz. Primary applications include radio telecommunications, broadcast equipment, medical equipment, computer, Precision Video, High definition studio broadcast, video switching and test instrumentation where frequent coupling and de-coupling are necessary.?
Bomar’s BNCs are available in an extensive variety of configurations and cable sizes and are impedance matched to either 50 ohm or 75 ohm.
??
Connector Body and Parts
Frequency Range
??ELECTRICAL
?? ??Performance
Test ? Specification
?? ??Impedance
50 ohm???0-4GHz
75 ohm.???0-1 GHz
? ??VSWR
1.30 Max.??MIL-C-39012
? ??RF Insertion Loss
0.2 db Min. at 3 GHz.??MIL-C-39012
? ??RF Leakage
??Working Voltage ( At Sea Level ).??-55 db Min. at 3 GHz.??MIL-C-39012
???Test Voltage ( At Sea Level)
1500V rms.??MIL-STD-202
???500V rms.??MIL-STD-202
? ??Insulation Resistance
5000 Meg ohms Min.???MIL-STD-202
?? ??Contact Resistance
3 Milli ohms Max.
?
?Don Bitters
