need some advice on taking this transformer apart.

[NR5P]

I am in the process of building a cw transmitter with a single 1625.  The transformer I'm wanting to use has a 550vct secondary which would be great but I'm confused.  It says secondary #1 which is what I need, secondary #2 5.0v, and secondary #3 which is not listed.  The transformer has 12 connections but I'm not sure which is which.  1-6 all appear to be on the same winding.  7-9 and 10-12 are on seperate windings.  7-9 I get the highest resistance so I guess this is the HV.  Is there a standard for reading these types of transformers for the future?  Also by taking nuts off of the 4 studs it should come apart right?  Or do the connections need to be unsoldered to slide through?

[WA1GFZ]

Put 12 volts AC on the primary and then measure each winding with an ac volt meter. Multiply each measurement by 10 to get a good idea of what happens when you apply 120 volts. Don't take it apart unless you have to. Good chance leads are soldered to the posts and they will be very hard to put back in place with short leads.

[WZ1M]

My guess is 1 thru 6 is a multi voltage primary. In other words, common/110/115/120/230/240 vac. Secondary #3 is probably 6.3 or 12 volts. If there is a terminal that will not read resistance to any of the other terminals, its a static shield and goes to ground.
Regards,
Gary

[NR5P]

Thanks, that's what it is multiple taps on the primary. That should have been obvious but it confused me with all the other taps.