From: Trevor Day
Subject: Re: How to check for a 50 or 75 ohm connector
Organization: Sunny Saltash
User-Agent: Turnpike/6.02-U ()
Date: Sun, 22 Dec 2002 11:54:18 +0000
NNTP-Posting-Date: Sun, 22 Dec 2002 11:55:18 GMT
In message <firstname.lastname@example.org>, DarkMatter
> Most folks that work with them on a daily basis can tell by
>examination of the rear, cable insertion end of the device in
>question. RG-58, RG-59, RG-62, RG-6, RG-174... etc. ALL have BNC
>iterations, and all are different sizes. Hell, RG-174 is like an
>eighth inch in diameter.
I have always believed that there is a diameter difference between the
two connectors (BNC50 and BNC75). This is re-inforced by the fact that
I own two Inter-series ex MoD connector kits which are identical
*except* one contains 75 ohm adaptors, the other 50. In this case they
can be easily told apart as one set has bright red insulation (75 ohms)
whilst the other (50 ohms) is white.
Looking at the pins, they appear to be pretty much the same size when
viewed from the mating end; this applies to both the 'male' pins in the
plugs and the 'female' pins in the sockets. There is a noticeable
difference however in the diameter of both male and female pins when
viewed from the rear. The 75 ohm pins are significantly slimmer. Both
50 and 75 ohm plugs and sockets will mate happily enough however, the
internal connectors will not. My conclusions are:
1. There is a diameter difference between the two that is difficult
to check by merely looking at the mating ends of the pins.
2. The MoD (and therefore industry who supply) believe there is a
significant difference between 50 and 75 ohm BNCs.
3. The above information is not much help unless you are using
Inter series connectors :-)
(Who by the way, is willing to put my name where my mouth is!)