Is it possible you are trying to solder to aluminum or steel pins crimped on the ends of the wires?? ?Those may be more difficult?to impossible to solder.
On Sun, Jun 6, 2021 at 7:35 AM Dennis Zabawa <kg4rul@...> wrote:
I am using the ones that come as kits of wires, cut to various lengths and with the ends preformed for insertion into solderless breadboards like these: