RE: "First BNC up to 3ghz is a reliable connector, no different from TNC.
Caveat; use good stuff and make sure you do not interchange
50 ohm BNC with 75 ohm BNC, really they are different!"
Yes they are different, look at the photo at
The 75 ohm BNCs are much more delicate and likely to be damaged because they lack the protection of the 50 ohm BNCs
However, they are physically inter-matable with no damage.
The center pin OD and shield "fongers' ID are identical, so can be inter-mated wtih no damage.
The impedance bump is probably not too bad below 5MHZ because before ATSC, when NTSC was used, virtually every BNC connector installed on 75 ohm coax and used in NTSC video equipment was the 50 ohm variety.
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