Connector grades as per video #1039

[tkamiya]

In one of the videos (#1039), Agilent technology calibration manager talks about different grades of connectors.  Metrology grade, instrument grade, and field grade to be exact.  So I headed over to Amphenol catalog and tried to identify which one is which.  I have instruments up to 2 GHz.  My concern is, I definitely don't want to damage the connectors, and if (as the video says) it can make up to 20db difference by repeatedly  using field grade connectors on instruments, I better avoid using field grade.

To my surprise, none of them are identified as "grades". 

My particular interest is going from N female to BNC female.  There are at least 5 different kind of connector of this type.  Would anyone be able to help me which is which?  I know RFX grade means "commercial".  Then, there is a lesser priced one without RFX designation which meets MIL spec.  Then there are ones that has to be ordered in quantity of 100s.

Can anyone assist me on this?

[darrell]

Get something decent quality and you will be fine. N connectors are rugged. What he said about damage applies more to 3.5 mm and smaller. The most important thing is to avoid mating questionable SMAs with precision 3.5 or 2.92 mm.  A cheap adapter from Ebay (some truly horrible connectors there) is likely to get you a broken connector on your equipment, but that's unlikely with anything from Amphenol or similar. Most of what Digikey and Mouser carry is field grade, but that's likely OK for your application.

Things to look for in a precision connector: stainless steel or BeCu outer conductor (not plated brass), BeCu inner contact, no slots in the outer of an N.

Repeatability won't be great with BNC in any case. I'm assuming the mention of 20 dB difference is in relation to return loss, which would cause transmission to change by something like 0.05 dB.

Inmet 5131, Rosenberger 53S151-K00N5 or Pomona 3288 would be decent options. I'd consider the last two to be field grade.

This is an excellent resource from NPL:
http://www.npl.co.uk/anamet-connector-guide
There's also IEEE-287, but it's behind a paywall.

[tkamiya]

Thank you.

I think I'm going to go with Amphenol standard type.  Yes, mention of 20db was a return loss.....