I am not 100% sure about this, but I don’t think so. I don’t believe it’s an HD-BNC connector or any other sort of standardized BNC. I was told by Proficnc (part of CubePilot, I think) on Facebook that the antenna connectors on the Herelink ground unit are custom. Maybe there is a supplier they can be obtained from, but I haven’t found one yet.
If you open up the back of the Herelink ground unit, you will find several standard U.FL connectors hooked up via internal wires to the custom external antenna connectors. To use an antenna of your choice, plug it directly into (via adapters if needed) one of those U.FL connectors. Be aware that U.FL connectors are only designed to be removed and attached up to about 30 times, so a permanently-attached adapter may be helpful for reducing wear and tear. I did this to add a parabolic high-gain antenna, and it worked well.
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