Re: Francophones

In message <nnd$23e91f0d$053bf96e@d25fd620e9918bf1>, Arie de Muijnck <noreply@ademu.nl> writes

On 2024-12-23 16:22, Ian Jackson wrote:

For many purposes you can ignore the difference between the 50 and 75 ohm impedances (and 60 if you ever come across any). However, be very aware only BNC 50 and 75 ohm connectors are mutually mechanically mateable (yes - they really are!). I don't know if any others that are.

>
Not recommended.
The center pin differs, a 50 Ohm BNC pin is thicker and may damage a 75 ohm BNC.
I'm cautious, most of my below 1 GHz equipment is 75 Ohms (from CATV company), the rest is 50.
>

For most of its length, the male BNC 50 ohm pin is actually the same diameter as the 75. However, the tip of the 50 pin is fairly 'blunt', while the 75 is more pointed.
I guess that if you are particularly clumsy while you are inserting a 50 male into a female 75, it might just be possible to have the blunter male pin a bit off-centre, and catch the side of the female receptacle, and splay it. However, despite 43 years working in the CATV industry, I failed to achieve this!
The real difference between the two impedances is that the amount of PTFE dielectric in the 75 has been minimised in order to increase (with some difficulty) the Zo from 50 to 75 ohms. IIRC, the 50 has a more-uniform structural RLR, so it the better connector at the higher frequencies.
--
Ian
Aims and ambitions are neither attainments nor achievements