[Garbz]

Ok there's 50ohm and 75ohm. I'm looking at the nonname brands that my local shop has. They have nothing written to say they are 75 ohm or not, so the question is how do I identify them?

 

[DaKi][er]

http://sosnick.uchicago.edu/BNC_50_75.html

jaycar are all 50ohm from what I remember, you might be lucky to get a 75ohm there

 

[Garbz]

Ahhh well they do have 75ohm plugs. Gold plated too for extra bling bling effect.
http://www.jaycar.com.au/productView...Max=&SUBCATID=

I was actually looking for sockets, but i think i found some at cliff electronics:
http://www.cliff.com.au/products/connectors/bnc.htm THe amphenol and neutrik connectors.

 

[Magsy]

I have a few Amphenol pcb mount sockets but they have a very small amount of insulation around the centre contact, maybe 2mm of teflon.
This is confusing because 50ohms has a thick insulation and 75ohm supposedly none?:|

Those deffo look right in the pictures though!

 

[Garbz]

Teflon is not used in the 50ohm jacks from what i've learnt. Amphenol only make 75ohm jacks as far as i can see on their website, although some are labled "true 75ohm" which leads me to believe some of their jacks aren't exaclty the correct impednace.

 

[Magsy]

Actually the one I have fitted is from Tyco Electronics, part number 1-1634622-0.

It looks like this

I bought several different ones, including an Ampehnol part number B6252H7-NPP3G-75T which looks just like above.
I also have Amp part number B6421A1-NT3G-3-75 which is a panel mount socket, this has no insulation around the centre female pin!! :|?

I have a 50ohm one too and that has more insulation in the middle than the 75ohm ones.

It's all a little confusing though and I'm still not sure I have real 75r sockets.

Cable plugs are easier, I bought Canare ones, they clearly have no insulation around the centre pin.

 

[chris719]

I have the same problem.. 75 ohm says the amp datasheet but it has that small amount of insulation around the center pin of the receptacle. I do have another, different, amphenol one that does not have any insulation around the center pin but I don't think that was specified as 75 ohms when I bought it.

 

[Garbz]

That's still 75ohm. It does not look like enough insulation to be a 50ohm plug. The 50ohms have considerably more, and are not teflon which in the link dakiller posted has different electrical characteristics then delrin.

Look at examples of the 50ohm plugs. You're looking at 2mm around the pin, not that 0.5mm that you have there.