From: Ian Walker
Subject: Re: How to check for a 50 or 75 ohm connector
Date: Sun, 22 Dec 2002 15:59:30 +0000
NNTP-Posting-Date: Sun, 22 Dec 2002 16:01:00 +0000 (UTC)
User-Agent: Turnpike/6.02-U ()
In article , Trevor Day
>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 :-)
The last is correct, the specification of Inter-Series adapters is
propriety to Greenpar and is in no way indicative of the internationally
agreed standards for BNC and N connectors.