Electronics > Beginners

Bad BNC Cable or am I misunderstanding their specs?

(1/3) > >>

windsmurf:
So I purchased five of what was described as  "RG59/U 75ohm 50cm ( 19.1/2") BNC Male to BNC Male Coaxial Video Cable"
I was planning on using them for short leads to a BNC to banana plugs, but I'm having issues with most them because resistance on the shielding connection is so high or totally open. 

So my question is, are these cables defective, or is the only thing the specs for a "Coaxial Video Cable" calls for is a good center connection, with high resistance or open on the shielding connection?

The last picture is what I was expecting.  That cable is from a different source, and cable itself is not RG59.




ataradov:
It is not clear from the pictures if your clips actually make a connection with the inner coaxial metal contact, not just rotating locking part. At leas in the first picture they are not, and that may explain the results.

tooki:
It looks to me as though you’re testing the bayonet shells, but not the actual mating surfaces for the shield. Those are the metal around the center dielectric.

See the image on http://www.contrik.ch/en-ch/faqs/how-important-is-shielding-on-a-bnc-connector . Only the gold plated surfaces are the mating surfaces.

See also these insulated BNCs, which are compatible with regular BNC. This illustrates what parts aren’t actually needed for the electrical connection: https://ec.staubli.com/products/includes/tm/hfline/bnc-sicherheits-steckverbinder_e.htm

David_AVD:
My guess is that those cables are junk.  Where did you buy them?

windsmurf:

--- Quote from: tooki on April 14, 2019, 09:12:33 pm ---It looks to me as though you’re testing the bayonet shells, but not the actual mating surfaces for the shield. Those are the metal around the center dielectric.

See the image on http://www.contrik.ch/en-ch/faqs/how-important-is-shielding-on-a-bnc-connector . Only the gold plated surfaces are the mating surfaces.

See also these insulated BNCs, which are compatible with regular BNC. This illustrates what parts aren’t actually needed for the electrical connection: https://ec.staubli.com/products/includes/tm/hfline/bnc-sicherheits-steckverbinder_e.htm

--- End quote ---

Thank you for the connection information.  I did probe the inside contacts using a needle probe but get the same results on the cables.  When I actually do use the cables to two BNC/Banana connectors and measure known voltages, its way off, and voltages are moving all over the place, even with the cables sitting very still. 

The auction is here:
https://www.ebay.com/itm/RG59-U-75ohm-50cm-19-1-2-BNC-Male-to-BNC-Male-Coaxial-Video-Cable/273561959972

I thought about leaving negative feedback but had mixed feelings about doing that.   Should one punish the seller for selling defective equipment unknowingly?... 
Or perhaps warn other buyers by leaving negative feedback as to the quality of his cables.... hmmm.....

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod