[time-nuts] BNC Question

[Oz-in-DFW]

No Stan, you are correct.

**True** 75 ohm BNCs (and Ns and TNCs as well) use a substantially
smaller center pin and no insulation support around the female contacts.
Mating a 50 ohm spec male part (plug) will invariably damage a 75 ohm
female (receptacle.) 

Amphenol made a **proprietary** series that maintained specs to 4 or so
Ghz when mated in the proper system impedance and would reliably
interate without damage. This was not a full spec part, but a
proprietary variant that was a market response to the damage probelms. 
They were widely used in broadcast video, and rarely used in RF
applications.

If need be we can pull the mil drawings as a group and compare them.   I
learned this lesson by proxy in the days I worked for a cable TV
manufacturer and a tech made the mistake for a second time and got his
pay docked the repair cost from HP.  Fortunately, the parts cost was
small.  Unfortunately he got to pay for a new cal on the instrument,
about 2 weeks pay for him *before* withholding.

Rich, N1OZ

On 4/9/2011 9:28 PM, Stan, W1LE wrote:
> Sorri, I must have been thinking type N connectors.
>
> Stan, W1LE
>
>
> On 4/9/2011 8:18 PM, Brucekareen at aol.com wrote:
>> Interestingly, 50 and 75-ohm BNC connectors have the same pin/shell
>> dimensions and properly couple together.  For more information go to
>> _http://www.cliftonlaboratories.com/august_2007.htm_
>> (http://www.cliftonlaboratories.com/august_2007.htm)  and  scroll
>> down to the 02 August 2007 entry.  There is a
>> link to the Amphenol  site for specifics about the connectors.
>>
>> I am planning to use an Extron video distribution amplifier for standard
>> frequency distribution.  The 75-ohm connectors will be OK.  These 
>> amplifiers
>> feed multiple 75-ohm outputs from a "zero-impedance" source by 
>> inserting a
>> 75-ohm resistor in each leg.  Some folks using these for  standard
>> frequency distribution change the resistors to 50-ohms.
>>
>> Bruce, KG6OJI
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>
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