until I realized most of it is probably 75ohms not 50, because among the 150 pieces I got, there are about 30/40 75ohms terminators. So I assume all the adapters and sockets in the lot, are also 75 ohms, bummer Would have to look at each of them one by one very closely to see if some of them by some chance are 50 ohms. Would be cool because from what I see it's old quality stuff, not modern Chinese junk. A lot of it is Radiall for starters.
If the center socket in the female has a cylinder of dielectric around it, it's a 50Ω. If it is just the bare socket, and looking rather fragile, it's 75Ω.
It used to be SOP in the video business (who are those that use 75Ω coax the most) to use 50Ω connectors with 75Ω cable, because the 50Ω is a bit sturdier. They had to stop that when the bandwidth had to increase to accommodate HD-TV, 720p and up.
OH !!! so you mean NO white dielectric piece AT ALL ?!
Lemme see ! Found an article on Wikipedia on BNC plugs... a pic comparing 50 and 75 ohms... pic below.
Hell you are right, ZERO white dielectric piece in the center !
I don't understand... from a video a few years back from Shariar, IIRC he said the thickness of the white dielectric bit varied depending on the impedance of the plug/socket.
So I was paying attention to that when looking at the pile of adapters I have in that box.. and indeed noticed some pieces have a very thick white dielectric piece, same as the 50 ohms sockets on my scopes, whereas other pieces have a slightly thinner dielectric, and others have an even thinner, realllly thin dielectric. See picture below where I compare 3 pieces side by side : leftmost is one of the 50ohms adapters I just bought from Farnell. Then center, a 75ohms termination from Tektronix, one can clearly see the white dielectric bit is visibly thinner. Then rightmost, another termination, which is again clearly even thinner still ! Then I searched some more in the pile of bits and found a BNC socket like you describe, with zero white dielectric in the middle... which I photographed next to a 50ohms socket.
WORSE STILL : among the very 50 ohms bits I just ordered from Farnell (made TRIPLE sure when ordering, that it was all 50 ohms not 75...)... I now notice that they do NOT have all the same thickness white piece ! Most of them have a thick piece, but the " Y " adapter has a slightly thinner piece ! Oh no !
I am properly confused now, let me tell ya !!!!!
What the hell is going on here ?!
My understanding was as Shariar said that the dielectric thickness and nature/material used, determines the impedance of the connector or cable. so surely if the thickness of the white piece varies, so does the impedance no ?!
Also, if we have a varying thickness among 50ohms connectors... that means that depending on what particular plug you shove into a particular socket... you will end up with an air gap between the two white pieces, a gap whose size varies depending on the plug/socket combo that you happen to be using. Surely an air gap is not good ? Never mind one that you can't even know/control the size of ?!
Oh no.... I am real confused now people.... if I can't even get super basic stuff like this, straight, I will never go very far in my electronics adventures I fear !
Wiki article
https://en.wikipedia.org/wiki/BNC_connector at any rate confirms what you said... plus video stuff is your line of business or used to be at least as I understand it.... so clearly you know what a 75 ohm socket and plug looks like so I trust you !
So that would tend to say that if it has ANY thickness of white stuff, it's 50ohms for sure, I can trust that ? And that it's not important if you mix and match plugs/sockets that have a different thickness of the white stuff...weird but hey.
Wiki article says that 75ohms connectors are good for 2GHz and 50ohms for 4GHz.
Oh boy....
Well any way, if white = 50ohms, then I am lucky and all the stuff I got in that box is 50ohms not 75ohms, so I have hundreds of Euros worth of Radial adapters and sockets, great !!!!
Lots of nice panel mount sockets, some cool 90° angled adapters, Tees and much more.