Re: QCX mini: RF output BNC or SMA #poll-notice

Jim Mcilroy

At one stage in my professional life I worked in a components factory which made SMA, TNC, SMB, BNC and you name it. We also made semi-rigid and flexible cable assemblies for space and general aviation applications.

The network analysers we used had SMA on the ports as we measured up to 26GHz in the day. They were good for more than 50 mate/demate cycles but they were of high quality.

I agree that TNC is a resilient connector and would like to see it used more.

If a connector fault was reported or something sent back we would measure what we could and if in doubt pot the connector and section it to see how the assembly materials fared. I did see one example of a faulty SMA where some metal of the inner connector dislodged, made its way through the dielectric to the outer core and short circuited.


PS BNC connectors are OK up to 4GHz

On 06/08/2020 14:39, Dave wrote:
The SMA is only rated for 50 mate/demate cycles, and that is for the real gold plated versions. Quite a nice connector for applications that call for a very few disconnects, like inside equipment.

There is a reason why the BNC is found on scopes and signal generators, etc.

The TNC is a close relative of the BNC, without the vibration induced connection noise.


On Aug 6, 2020, at 09:34, Hans Summers <hans.summers@...> wrote:

Hi Russ

I have to admit to a preference for BNC. 

What kind of issues have they seen? 

73 Hans G0UPL

On Thu, Aug 6, 2020 at 4:28 PM Russ@va3rr via <> wrote:
The NanoVNA group has been seeing some issues with SMA connectors.

It's too bad TNC connectors aren't more prevalent in amateur equipment.  I have some LMR cables with TNC connectors and they really are quite robust...

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