HifiBerry Digi panel-mount BNC wiring

[itsikhefez]

Hi all,

I want to wire the optional BNC connection on the HifiBerry Digi+ Pro to the chassis panel.

I've got this Neutrik BNC connector
NBB75SI | Neutrik

I've measured the pads on the Digi board with my DMM by measuring from the pads to the RCA connector shell and pin.
It looks like 3 out of the 4 pads are all ground (2 large ones + 1 small one), the remaining one is signal.
Resistance between signal and ground is 0.7.

My 2 questions are:
1) Which type of wiring should I use? The wire length will be short, 2-3 inches (50mm-80mm). I've got some Mogami W2546 which is a 75ohm coaxial cable, although using a twisted pair would be easier.

2) Do I need to put a 75R resistor across the pads on the PCB?

Thanks!

 

[grimberg]

I suggest you purchase and install a PCB mount BNC jack.

73137-5003 Molex | Mouser

That one includes a lockwasher and nut that will give a nice finish on the front panel.

 

[itsikhefez]

Could you please elaborate why?

Besides, the RPI is enclosed in a custom case with display, power supply etc...
The ethernet/USB side is flush with the panel, the HifiBerry connectors are perpendicular to that

 

[grimberg]

The BNC in that link fits perfectly in that empty space on the PCB and the jack will protrude just like the adjacent RCA jack does. Since you will have to drill the panel, just make the hole to match the jack I linked.
Disregard the word "front" in my previous post.

 

[itsikhefez]

I already have a case and panel, please see photos.

I appreciate your suggestion, but that is not the question I was asking.... what is wrong with panel mounting ?

 

[grimberg]

I have half a dozen Raspberry Pi computers which I use for audio streaming, home automation and other assorted tasks. Two are mounted on standard cases, two on custom cases (Custom built case for Raspberry Pi music streamer) and the other two don't have cases. One of my favorite aspects of the Raspberry Pi computers is in the fact that they are compact and can be moved around as a single piece, even without a case. If you use the panel mount BNC you loose that flexibility. If that is not an issue for you, just wire it carefully and be happy!

 

[itsikhefez]

Thanks for your thoughts.
I too have a few RPI's around some enclosed and some not. This particular one is going to built as a dedicated streamer in my audio rack, so I don't need the flexibility in the case.

In terms of wiring though, is the no difference of coaxial, twisted pair wiring and/or terminating with 75R ?

 

[grimberg]

If you have Mogami handy I suggest you use it.

 

[bravem01]

This is how I did it. Simply wire 75 ohm coax to insulated panel mount rca or bnc in your case

 

[itsikhefez]

bravem01, I missed your comment when it was written.. thanks for the info.

I actually ended up using a generic coaxial wire.. the streamer itself came out pretty.

Bonus: the display matches my AMB alpha10 preamp