If you just read and follow the instructions, step-by-step, it should be very clear how long the final length will be:

  • Cut each wire to the specified cut length. 
  • Prepare the Twinlead Feedline (B+C).
  • Insert the two Length A's into the Center Insulator.
  • Insert the two ends into the End Insulators.
  • Tie a knot near the end of the wire.  The knot is:
    • 15cm from the end on 20m
    • 10cm from the end on all other bands.  
  • The knot reduces the length by about 2cm.
  • THEREFORE  each leg  is  now  2 cm  shorter  than  the  original specified Length A:


(NOTE:  The 3-Band Spiderbeam has different lengths!)


We use the same scheme for all versions of the Spiderbeam Yagi.  Therefore if you have any other version (i.e. 3-Band, Low Band, etc.), simply follow the same scenario:  Cut-Length minus 2 cm.