[time-nuts] BNC question

Chuck Harris cfharris at erols.com
Sun Apr 10 16:53:08 UTC 2011


Greg Broburg wrote:

>> receivers used 75 ohmantenna
>> <http://en.wikipedia.org/wiki/Antenna_%28radio%29>inputs, so they
>> often used 75 ohm BNC connectors.
>>
>
> I had remembered that it was a 75 ohm that would damage a
> 50 ohm socket. This article states that a 50 ohm would
> damage a 75 ohm socket.
>
> Greg

Sadly, you remembered incorrectly.  Both 75 ohm, and 50 ohm
BNC parts use the same center pin assemblies.  The only
difference is the 75 ohm part has the teflon shroud removed
from around the female pin.  They mate in all combinations
without any risk of damage.

The N style connector is a different story, however.  It is
a higher performance connector, and as a result they needed
to make the center conductor of a 75 ohm connector smaller
in diameter all the way through, so the 75 ohm center male
pin is slender, as is the 75 ohm center female pin.  If you
jam a thicker 50 ohm center pin into the slender 75 ohm
female pin, it will bend the socket leafs out and probably
break it.

-Chuck Harris




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