From: John Woodgate
Subject: Re: How to check for a 50 or 75 ohm connector
Date: Tue, 24 Dec 2002 20:02:38 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Tue, 24 Dec 2002 20:44:14 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Graham Sharp
wrote (in <firstname.lastname@example.org>) about 'How to
check for a 50 or 75 ohm connector', on Tue, 24 Dec 2002:
>On Sun, 22 Dec 2002 23:16:45 +0000, John Woodgate
>>I read in sci.electronics.design that Alun Palmer
>>wrote (in ) about 'How to
>>check for a 50 or 75 ohm connector', on Sun, 22 Dec 2002:
>>>The centre pins on 75 Ohm BNC plugs are very slightly larger, so that
>>>inserting them in a 50 Ohm BNC socket causes damage by enlarging the hole.
>>>I used to work in a lab where we had both.
>>That cannot possibly be so. If anything, the 75 ohm pin MUST be smaller.
> I don't know if these were 'certified' BNC, but I can recall that on
>equipment I worked with about 30 years ago, the pins of 75 Ohm plugs
>were smaller than 50 Ohm, probably to allow for the fact that the
>split sockets that they mated with had smaller OD. Repeated insertion
>of 50 Ohm plugs into 75 Ohm sockets on a certain type of equipment
>eventually resulted in one of the four segments of the socket breaking
>off. . .
This gels with my vintage hardware here. It seems that ONCE, the 75 ohm
parts had a smaller pin, but now they don't.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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