Transformer and voltage drop

Hi All,

I'm assembling a PSU for my servo setup.

It's a simple design:
- AC input, fuse, 2-pole switch, inrush-current limiter
- 1.8 kVA toroidal transformer w. 2x30 V secondaries
- rectifier bridge
- four 10 000uF caps

I'm testing it with various loads, and the DC voltage drop I'm seeing
looks surprisingly big. This is all explained in my blog at
http://www.anderswallin.net/2007/06/1800-w-80-v-psu-for-servos/
(scroll down, there are pics in the comments too!)

Testing only the AC side (no rectifier and no caps) gives me a voltage
drop of around 0,7 V for every amp of current. But with the rectifier
and the caps connected I see 1.9 V of drop, which sounds quite big!

any ideas on what is going on here? Should I be worried, or is this
typical for large toroidal transformers?

thanks,

Anders