You posted this same question on QRZ, two days ago -- but never responded to the answers received.http://forums.qrz.com/showthread.php?373652-IC2100-antenna-connection
IC-2100 Service Manualhttp://www.repeater-builder.com/icom...ice-manual.pdf
PC Board X-Ray layouts in Section 8
Parts List for IC-2100 in Section 5
Page 5-3 of the Service Manual (Parts List, Main Unit)
L20 (Inductor, part number: 6110001550, LA-235) is first component from that point (W3) in the schematic.
Many small SMT parts (on both sides) of the double-sided Main Board on that radio.
You will find the parts at SO-239 RF connector on Main Unit (PC board) are Inductors (L) or Capacitors (C).
CONSENSUS: JUMPER WIRE from SO-239 Center Pin to Main Unit (PC Board) at W3.