BNC cables and connectors

Thread Starter

upand_at_them

Joined May 15, 2010
766
Hi guys,

I'm looking for recommendations for BNC cables and connectors. I do this for fun so it doesn't need to be top-end. I have an oscilloscope and signal generator and now that I want to test stuff I realize that I don't have any cables to help out. I'm working on audio and HF radio circuits. It's winter here so no hamfests to check out. Is there anything decent that won't break the bank?

I probably need:
BNC male to BNC male, short cable
BNC male to BNC male, connector/adapter
other suggestions?
 

jpanhalt

Joined Jan 18, 2008
11,088
I like the RG316 (50Ω). It's not as bulky as the larger cable and works nicely with the SMA type connectors too, which you will surely come across.
 

andrewmm

Joined Feb 25, 2011
1,645
just be careful,
there are 75 ohm and 50 om BNC's,
if you plug 75 into a 50 ohm, then they are never a good match again,
get 50 ohm and stay with it ,
 

dl324

Joined Mar 30, 2015
12,931
BNC male to BNC male, short cable
BNC male to BNC male, connector/adapter
other suggestions?
You'll probably need more than 2. I have dozens handy around my scope and equipment where I use them.

Ready made seem overpriced at retail. I bought hundreds on eBay at good prices. I also have some cable and connectors to make up my own.

You'll also want some T connectors and a number of BNC female to grabbers. I make the latter using salvaged BNC female connectors I bought on eBay, wires, grabbers, and heatshrink. Some BNC female to banana plug are also handy if you have equipment with appropriately spaced banana jacks.

If you're not working on 50 or 75 ohm stuff, you can use either or both. If you are, you need to match the impedance of the connectors and RG-cable.
 
Last edited:

dl324

Joined Mar 30, 2015
12,931
When building your own equipment you should pair banana jacks with 0.75" spacing.
I do. So do those Chinese power supplies, but they put earth ground between + and -, so I can't use my BNC female to banana jack connectors.

I built these in the 70's:
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Last edited:

MrChips

Joined Oct 2, 2009
23,965
I do. So do those Chinese power supplies, but they put earth ground between + and -, so I can't use my BNC female to banana jack connectors.
What you can do is bridge the -ve post to GND and now you can use the 0.75" spacing between GND and +ve.
(Of course, assuming that a grounded +ve supply is ok with you.)

One of my earliest construction project was a 5VDC 1A regulated power supply which I still use today.
 

dl324

Joined Mar 30, 2015
12,931
What you can do is bridge the -ve post to GND and now you can use the 0.75" spacing between GND and +ve.
(Of course, assuming that a grounded +ve supply is ok with you.)
That supply doesn't use binding posts for the banana jacks so it takes too many connectors to do that. I have some shorting banana plugs to connect adjacent jacks, but I need to use a stacking banana connector to get the proper height. I just modified my 2.1mmF to banana plugs to accomodate 1.5" instead of 0.75" or use banana plug to grabber wires.

Besides, I don't usually connect power supply ground to earth ground.
 

dl324

Joined Mar 30, 2015
12,931
I checked the BNC connectors for my security cameras and DVR and they use 50 ohm connectors when they should be using 75 ohms.

The cheap DSO kits I have all use 50 ohm connectors. All of my high end test equipment uses 50 ohms.

I have no concerns about reflections for the work I currently do; none of it requires 50 or 75 ohm characteristic impedance.
 

andrewmm

Joined Feb 25, 2011
1,645
unless you need to start thinking about smith charts and VSWR, the impedance mismatch of a 75 ohm or 50 ohm BNC is not going to matter.

What will matter is if you plug 75 into 50 ohm,
50 is IMHO the standard in "most" test equipment, stick with it, and don't have both,
just check what you purchase is 50 ohms or what ever you decide on,
 
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