Greetings Saarlander.
I did extensive avionics work on a C-90 a couple of years ago, but all we did with the ADF was to remove it, and remove the single RMI...
You presumably have a single AC source in that plane, so no phasing conflict should be expected. If you want to go into this deeper, you will need to know the model number of the ADF receiver, RMIs and VOR receivers, and whether there is a separate module for driving the RMIs. You may contact me offline if you want.
We lived in Jaegersburg, bei Homburg, in 1966-7, and it was idyllic.
GB