[Elecraft] BNCs

[Joe Subich, W4TV]

> Although I have not studied the mechanical Standard for 75 ohm BNCs,
> I would VERY surprised if the dimensions of a proper 75 ohm connector
> would prevent it from mating with a proper 50 ohm connector. Have you
> studied such a spec?

Yes, I have used both in the TV stations - 50 Ohm for RF systems and
75 for video systems.  The center pin (male) and contact (female)
*ARE DIFFERENT SIZE*.  Forcing a 50 Ohm connector into a 75 Ohm socket
will split the center contact while putting a 75 Ohm connector into a
50 Ohm socket will result in insufficient tension on the center pin
(and unreliable contact).

73,

    ... Joe, W4TV


On 2014-10-13 12:45 PM, Jim Brown wrote:
> On Mon,10/13/2014 9:30 AM, Peter Torry wrote:
>> It may not make a difference to performance on HF but it does matter
>> because the centre pins have different diameters of solder pot / crimp
>> barrel to match the cable impedance used.
>
> What matters is that the connector match the physical dimensions of the
> cable so that it can be properly installed, and this is true regardless
> of impedance.
>
>> Also incorrectly mated connectors risk damage to their centre
>> connectors by forcing the engagement.  Use the correct connector for
>> the cable in use.
>
> Zo depends upon o.d. of the center conductor with the connectors mated,
> and would be established by the o.d. of the female pin receptacle, not
> the o.d. of the male tip. Although I have not studied the mechanical
> Standard for 75 ohm BNCs, I would VERY surprised if the dimensions of a
> proper 75 ohm connector would prevent it from mating with a proper 50
> ohm connector. Have you studied such a spec?  I'm quite active in
> international Standards work (with the AES) and that sort of
> incompatibility is something we make certain to avoid!
>
> 73, Jim K9YC
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