:lol:
If you want to use this transformer to feed a rectifier block with holding cap at output, then the rectifier diodes will sink current pulses from transformer, and for tought the average level of continous current sink from cap, these pulses must have a high current amplitude, and can produce a droped voltage on transformer bigger than you expected. Trying to increase the cap value will not improve anything, in some cases can be even worse, because when cap increase the conduction time of diodes decrese and current pulses from transformer becomes thicker and higher. This effect is much affected by the stray inductance of the transformer, but a transformer without stray inductance not exist, so try to compute, at least approximativelly, the amplitude of the current pulses.