It's possible though they were running them below 1500V and if so the plate-to-plate Z would drop quick and they could be 5.5K instead under those circumstances. You know, what you might do is connect the primary to 110V AC and look on the secondary with a scope to see if the voltage goes down or stays about the same. Just ground the primary's center-tap to the 3rd ground prong of your wall outlet. If the peak-to-peak voltage stays about the same on the secondary then it's a 1:1 ratio. If it goes down then it’s a step down. That bit of information would be the most helpful right now I think. .