[CQ-Contest] Balun design

[Guy Molinari]

I need a balun design to match 50 ohm unbalanced to 100 ohm balanced (2:1).  
  I have a T-200-2 core and am winding it as follows:

A bifiliar winding with one long and 1 short wire.   This goes for 12 turns 
and then the shorter wire stops at the halfway point.   The longer wire 
continues for 12 more turns.

When I test it with my MFJ-269 (2 50 ohm resistors in series),  the best SWR 
I get is 2.1:1.   The resistive and reactive values are both about 45 ohms.  
  I've tried removing/adding turns to the primary and secondary windings and 
the SWR gets worse.

Am I missing something?   Is there a better way?

73
Guy, N7ZG