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From: Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>
Newsgroups: sci.electronics.design,sci.electronics.repair
Subject: Re: Francophones
Date: Tue, 24 Dec 2024 01:16:31 -0000 (UTC)
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Ian Jackson <ianREMOVETHISjackson@g3ohx.co.uk> wrote:
> In message <vkckph$1cvdj$1@dont-email.me>, Jeroen Belleman 
> <jeroen@nospam.please> writes
>> On 12/23/24 18:58, Ralph Mowery wrote:
>>> In article <nnd$23e91f0d$053bf96e@d25fd620e9918bf1>, noreply@ademu.nl
>>> says...
>>>> 
>>>> On 2024-12-23 16:22, Ian Jackson wrote:
>>>>> For many purposes you can ignore the difference between the 50 and 
>>>>> 75 ohm impedances (and 60 if you ever come across any).
>>>>> However, be very aware only BNC 50 and 75 ohm connectors are 
>>>>> mutually mechanically mateable (yes - they really are!). I don't 
>>>>> know if any others that are.
>>>> 
>>>> Not recommended.
>>>> The center pin differs, a 50 Ohm BNC pin is thicker and may damage a 
>>>> 75 ohm BNC.
>>>> I'm cautious, most of my below 1 GHz equipment is 75 Ohms (from CATV 
>>>> company), the rest is 50.
>>>> 
>>>> 
>>>> 
>>> It is the N connector the center pin is different.  The BNC pin is 
>>> the
>>> same.  It is the ammount of dialectric (insulation) in the BNC that
>>> makes it a 75 or 50 ohm connector.
>>> 
>> 
>> N connectors are good, but the fact that 75 and 50 Ohm connectors
>> are similar enough to mate, but not nearly enough to do so without
>> damage or malfunction is perverse. When I took charge of the
>> electronics lab, it took a while to sort them out and to eliminate
>> the victims of mismatched matings. (I was always amazed at the
>> sheer quantity of connectors in a busy lab.)
>> 
>> For BNCs, there *is* a difference, but it doesn't usually matter.
>> I kept 50 and 75 Ohms separate, but when put to the test, many
>> 75 Ohm connectors turned out to really be 50 Ohm ones in disguise.
>> 
>> In a pinch, BNC and N can even mate between them. I'm not sure if
>> that's deliberate or accidental.
>> 
> Yes - the 'innards' are essentially the same. IIRC, the BNC innards also 
> mate with C-connectors. I think it's deliberate. After all, its the 
> innards that carry the RF.

A type N male will also mate with a BNC female. 

Cheers 

Phil Hobbs 

-- 
Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /
Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics