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

George Korper

I like that idea! 

On Thu, Aug 6, 2020 at 12:43 PM Alan de G1FXB <g1fxb.groups@...> wrote:
I fully expect I'm in a group of one.
But especially as the QCX was first requested and now being offered as field optimised.......

Imagine the gods gave were kind hearing the rarest of rare DX station,
when you trip over the feeder and it pulls out the back of your radio, or the patch lead that was OK when you packed it away you find is no longer.......
I know I don't want to be fudging with SMA connectors and mini coax with minimal hand and soldering tools on a hill top or worse still atop a ski jump.
SMA's were not "invented" to be a regularly disconnectable connector, then add to it some dust & dirt "grinding paste" and who knows how durable it will be on the trails.

At least some  BNC's styles are available as "Solderless" that will suffice for field repairs to get you out of trouble, even then cable preparation can be a faff when you discover at the most inconvenient time you have a bad cable.
 in the past either by luck or by design the  QRP labs enclosures for the U3 has allowed for substitution and the drilling out & fitting of a female shielded Banana Plug receptacle, more commonly known as a SO239
Assembled PL259 can be reclaimed easily enough on hill tops, although solderless and non-crimp also exist, the cable can be remade without the need of a soldering iron for field day repairs if need be if I have forgotten to pack a few spares......

We all have a favourite "Shack Standard" RF Connector and like all good standards, they are far from it......

If the QCX enclosure had what ever the preferred end up being  "RF Out" suitably separated from the next connector then we all could pick & choose "our own" favourite SMA, TNC, SMB, BNC Chassis socket. Or whatever........?


On 06/08/2020 14:49, Jim Mcilroy via wrote:

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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