Goobay 50 Ω coaxial cables with "like BNC" connectors
Warning on Goobay 50 Ω coaxial cables with very bad BNC connectors. These cables are very cheap but are unusable !
I recently bought 6 Goobay cables with “BNC” connectors installed at each end.
These cheap cables are absolutely unusable.
These connectors, described as BNC type, are not !
Description of non-conformance of supplied connectors to BNC standard
1. The metal bushing ensuring continuity of the cable shielding does not touch the BNC base of the device on which the cable is connected because its outside diameter is too small ! We can just hope for erratic contact !
With the result that when the cable is connected to the BNC base, it can be moved laterally, which is impossible with a real BNC connector.
2. Center pin for cable core continuity is not centered
3. The end of the metal bushing consists of folded metal parts (not present on the BNC standard) that damage the PE insulation of the BNC base during each disconnection
Examination of the cable itself
4. The core of the cable consists of a coppered steel wire of 50/100 mm with traces of iron oxide on the surface!
The resistance of the core on the 2 m long cable is 1.062 Ω, compared to 61 mΩ for a «normal» Amphenol construction cable of the same length !
5. The shielding of the cable is provided by an aluminum sheet and a shield made up of about thirty 10/100 mm diameter … coppered iron wires
For the 2 m long cable, the overall shield resistance is 426 mΩ, compared to 26 mΩ for the “normal” Amphenol construction cable.
6. Goobay cable capacity is approximately 60% of normal cable capacity.
The insulation has an elastic consistency: it is a kind of foam in which the nail penetrates.
This lower capacity may seem like a good thing at first, but what about the characteristic impedance of the cable and its dielectric strength ?
Documents
Two pdf files (one in English and one in French) contain the text, more details and photos describing the problem.
An Excel file contains the measurements made in points 4 to 6.
These cheap cables are absolutely unusable.
These connectors, described as BNC type, are not !
Description of non-conformance of supplied connectors to BNC standard
1. The metal bushing ensuring continuity of the cable shielding does not touch the BNC base of the device on which the cable is connected because its outside diameter is too small ! We can just hope for erratic contact !
With the result that when the cable is connected to the BNC base, it can be moved laterally, which is impossible with a real BNC connector.
2. Center pin for cable core continuity is not centered
3. The end of the metal bushing consists of folded metal parts (not present on the BNC standard) that damage the PE insulation of the BNC base during each disconnection
Examination of the cable itself
4. The core of the cable consists of a coppered steel wire of 50/100 mm with traces of iron oxide on the surface!
The resistance of the core on the 2 m long cable is 1.062 Ω, compared to 61 mΩ for a «normal» Amphenol construction cable of the same length !
5. The shielding of the cable is provided by an aluminum sheet and a shield made up of about thirty 10/100 mm diameter … coppered iron wires
For the 2 m long cable, the overall shield resistance is 426 mΩ, compared to 26 mΩ for the “normal” Amphenol construction cable.
6. Goobay cable capacity is approximately 60% of normal cable capacity.
The insulation has an elastic consistency: it is a kind of foam in which the nail penetrates.
This lower capacity may seem like a good thing at first, but what about the characteristic impedance of the cable and its dielectric strength ?
Documents
Two pdf files (one in English and one in French) contain the text, more details and photos describing the problem.
An Excel file contains the measurements made in points 4 to 6.
Discussion (3 commentaire(s))