BNC connector to board

[charnich]

HI, I'm trying to add a BNC connector to the control board of a machine that traces an eyeglass frame for a pattern to cut lenses so that I can add ARCNET functionality. I don't have much experience with soldering components to boards but I want to give it a go. Basically there is an cutout in the case about 10 inches from the solder terminal in the machine so I'll likely need a receptacle with leads. I'm attaching a pic of the board. Could anyone tell me what the solder point are for? Also, there is another solder point in close proximity titled "BNC" that stands alone. I see there are a variety of BNC connectors available and I'm not sure which one to get. Any advice is greatly appreciated.

 

[davenn]

Hi
welcome to the forums

Within the circles, the outer 3 solder points are for the GND terminals of the BNC connector. the centre solder point is for the centre pin

You will just have to go through the farnell ( element14), mouser, digikey catalogs and see if they have one with 3 GND terminals .... not one I have seen before they are usually 2 pin or 4 pin GND terminal

That other tiny point may be just a testpoint ... or may not even be connected to anything .... hard to tell without seeing the board up close and with a bright light behind the board to show up any tracks

Dave

 

[charnich]

Hi Dave and thank you for the speedy reply! Do I have to use all 3 grounds or could I use something like this?

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_256832_-1

I was thinking I could just connect the ground to 1 lead and the center to the other and route the wires to where I could mount the connector to the external case. Is there any reason I would need to solder the receptacle directly to the board?

Hi
welcome to the forums

Within the circles, the outer 3 solder points are for the GND terminals of the BNC connector. the centre solder point is for the centre pin

You will just have to go through the farnell ( element14), mouser, digikey catalogs and see if they have one with 3 GND terminals .... not one I have seen before they are usually 2 pin or 4 pin GND terminal

That other tiny point may be just a testpoint ... or may not even be connected to anything .... hard to tell without seeing the board up close and with a bright light behind the board to show up any tracks

Dave

 

[davenn]

Hi Dave and thank you for the speedy reply! Do I have to use all 3 grounds or could I use something like this?

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_256832_-1

I was thinking I could just connect the ground to 1 lead and the center to the other and route the wires to where I could mount the connector to the external case. Is there any reason I would need to solder the receptacle directly to the board?

well the link you gave shows an inline connector so its not going to mount on the case anyway.
If you want to mount a connector on the external case you would need a bulkhead or chassis mount type socket ( not an inline type)
Then if you do mount on the external case you will need a short length of coax NOT twinlead (as shown in that link)
There are a number of coax cables available that are small diameter. Depending on what type of signal is going through that connector you may well be able to use audio screened lead instead of coax

Dave

 

[charnich]

Oh I see. Just curious, what is wrong with twinlead in this sort of application?

Thank you for your help.

well the link you gave shows an inline connector so its not going to mount on the case anyway.
If you want to mount a connector on the external case you would need a bulkhead or chassis mount type socket ( not an inline type)
Then if you do mount on the external case you will need a short length of coax NOT twinlead (as shown in that link)
There are a number of coax cables available that are small diameter. Depending on what type of signal is going through that connector you may well be able to use audio screened lead instead of coax

Dave

 

[shrtrnd]

The PURPOSE of coax over twin lead, is to reduce spurious signals from outside
the circuit from interferring with the signal on the coax cable. It reduces outside radio
frequency interferrence with the operation of your instrument.
(The coax braid around the signal wire in the coax does that).

 

[charnich]

Oh I see. Thank you!

The PURPOSE of coax over twin lead, is to reduce spurious signals from outside
the circuit from interferring with the signal on the coax cable. It reduces outside radio
frequency interferrence with the operation of your instrument.
(The coax braid around the signal wire in the coax does that).