Just got more of the R6-USB and I need to get more range out of them so I want to solder the SMA connector to it for use with an external antenna. Here is a picture of how I "think" I need to place it, but want to make sure as it seems that the legs of the SMA adaptor end up touching other pads.
Thanks
(https://i.imgur.com/AaRvMPm.jpg)
Looks just like the photo Felix posted of a SMA on a Moteion
So just solder the center pin and the one to the right of the pin (toward the center of the board)?
I would centralise it more so the outside pin of the SMA is a lot further away from RF output (i.e. that pin is closer to the outer IO pins). What you have there is a small capacitor between the ground and the RF pin, and even a few pF is significant at those frequencies.
Edit: I'd actually go one step further and remove that outer pin from the SMA connector completely. If you assume that even has 0.1pF capacitance the impedance at 1GHz is 1/wC, or 1/(2*pi*1e12*0.1e-12), or about 1.6ohms. So at RF thats 50R output impedance of the RFOUT with a 1.6ohm to ground.
Mark.