[time-nuts] BNC question

[Alan Melia]

Hi Stan this one has been covered before the pins are the same size the
difference is in the amount of dielectric round the socket in the
female....the 75 ohm one hase the socket poking free of the ptfe and on the
50 ohm it is flush with the end. The the centre connectors mate correctly
together.

Alan G3NYK

----- Original Message ----- 
From: "Stan, W1LE" <stanw1le at verizon.net>
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Sunday, April 10, 2011 12:32 AM
Subject: Re: [time-nuts] BNC question


> Hello Joe,
>
> It probably is a 50 ohm BNC female connector.
>
> Check out a male loose connector with a known 50 ohm center pin.
> Does the male pin fit the female nicely ?
>
> I have rarely seen a 75 ohm BNC center pin, but they are out there.
> I have never seen a 93 ohm BNC center pin. (never looked for them.)
>
> If you apply a true 75 ohm BNC male connector to a 50 ohm BNC female it
> may not mate properly with a
> low resistance joint.   ie. poor mechanical fit.
>
> If you apply a 50 ohm male BNC into a 75 ohm BNC female, you will
> probably destroy the female center pin.
>
> Cost wise, the 50 ohm BNC connectors are the least expensive, so that is
> what manufacturers use.
> For most applications the electrical length of the center pin is a very
> small part of a wavelength,
> so there is only a very small impact on the impedance, on the rare
> occasion impedance is of concern.
>
> Stan, W1LE
>
>
>
>
>
>
> On 4/9/2011 6:53 PM, Joseph Gray wrote:
> > I have an old Arcnet hub that I want to salvage the isolated BNC
> > connectors from. Arcnet used 93 Ohm coax. I know that there are 50 Ohm
> > and 75 Ohm versions of BNC connectors, but the ones from the hub look
> > like a 50 Ohm BNC to me.
> >
> > I want to use these isolated BNC connectors for a frequency
> > distribution amp. What do you think?
> >
> > I'm still trying to find some old Ethernet cards for the transformers.
> > I know the cards will have BNC connectors, but the hub has eight
> > matched BNC connectors, so using them would be preferrable.
> >
> > Joe Gray
> > W5JG
> >
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