does anyone have any data concerning 50 ohm transmission lines
starting on the first layer and using vias to transport it to an inner layer.
I have looked at the IPC specs concerning microstrip etc.  good info.
unfortunately it just doesn't mention anything about how to get a 
impedance controlled line from one layer to the next.  I know that 
someone out there has done the numbers or knows where to go to
get them.  Please let me know 

thanks in advance.