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


Graham, VE3GTC
 

common practice with very expensive test gear costing many  thousands or tens of thousands of dollars which use SMA connector is to use a "connector saver".

A SMA connector saver is little more than a good quality SMA male to SMA female adapter:

image.png

screw on types are common but there are also push on types as well: https://www.deltarf.com/pdf/connect_save.pdf

It is cheaper to through away a $20 SMA male to female adapter than it is to replace an equipment mounted SMA connector on a $30,000 piece of test equipment.

I am not sure the APC3.5 connectors are the answer for the nanoVNA's.  These are really for many GHZ applications.

Not knowing just what type of SMA's that have been used on these devices, I would guess that typically they are the inexpensive SMA connectors sourced from Asia costing a few dollars rather than good quality brand name ( i.e. Amphenol, Pasternack, Johnson, etc ) with proper gold plating and not "gold like" plating or stainless steel costing tens of dollars. You get what you pay for.

Using good quality N connectors is probably a far better solution all round but they are certainly no miniature.

Making things ever smaller and more miniature isn't always the best way although it seems many think that smaller is better.

A case mounted connector gives the builder the option to choose what best fits their requirements be it SMA, BNC, F type, or binding posts.

cheers, Graham ve3gtc


On Thu, Aug 6, 2020 at 5:31 PM <namerati@...> wrote:
On Thu, Aug 06, 2020 at 06:28:35AM -0700, Russ@va3rr via groups.io wrote:
>The NanoVNA group has been seeing some issues with SMA connectors.

The consensus at the NanoVNA group was that the "ideal" solution was the
APC3.5 connector:
https://www.maurymw.com/pdf/datasheets/5A-011.pdf

Unfortunately this is not exactly cheap.

Since professional grade test equipment uses SMA connectors, where they
are mated thousands of times over the life of the instrument, it seems
unlikely to be *that* much of an issue for a HF transceiver where
connector impedance is of such little importance that people are
suggesting RCA plugs instead (!!!).

(why not binding posts?!)

Personally I am quite alright with using SMA in the field and I much
prefer to save the size/weight.

However the poll as given omits the option of including both SMA and BNC
footprints on the PCB, which seems to be clearly the best option!




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