I have a bare uBITX 3-30 MHz transceiver board per http://www.hfsignals.com/index.php/ubitx/
Looking at the hookup directions and other pictures on the site, the designer's recommendation is to simply hook a BNC jack to the main board through a (short) two-wire jumper (fractions of hookup schematic and pic below).
What I would like to do is add an additional SMA output in parallel with the BNC adapter to try things with other antennas and gear I already own without re-opening the case and swapping two-wire jumpers. It seems it wouldn't be much different than connecting a BNC tee to the output with a SMA adapter on one end and only using one or the other and leaving an open port.
What issues are there with mounting multiple RF connectors in parallel if you only intend to use one at any one time?
Are there similar issues with leaving an open Tee on a line?
Best Answer
For speeds under 50MHz transmission line effects are usually not a problem for the short distances on the PCB above. The SMA connector would add a small capacitive load (probably in the pF's range, if your fine with that then I'd solder it on. I would not plug in two things at once as they would not be matched.
The BNC connector above is also not impedance controlled, so I'd say an SMA would be fine.