Been wrestling with this as a technical problem but found an easy solution.
This is for people who have “stuff” and don’t like to buy things.
The whip would not connect to the pin of the BNC.
So got a Phono socket to BNC plug adaptor.
Cannibalised a Phono plug to get the central pin out - these are hollow.
Tinned the end of the whip and heated the pin with the 100W soldering iron.
Filled full of solder and then pushed the whip in.
Now we have a whip with a phono centre pin securely attached.
Push the pin into the phono to BNC adaptor.
Over the top put the plastic phone plug outer cover that you kept from dismantling the phono plug and fill full of araldite.
Now you have your own whip antenna.
Trim to calculated resonant length.
Not suitable for HF by the way!