[R-390] Isolation transformer questions

[Kenneth G. Gordon]

I think Barry (X) asked about connecting two of the secondary 
windings, a lower voltage one and a higher voltage one, in 
PARALLEL, hoping to get an "average" voltage.

This WILL NOT work, as the winding with the higher voltage 
will simply try to pull the winding with the lower voltage up to 
the higher voltage, causing the higher-voltage winding to put 
out a lot of current, possibly overheating the transformer.

He could, possibly, GET an "average" voltage simply because 
the higher-voltage winding would be so heavily loaded that its 
output voltage would be lower.

I don't think this is a good idea.

Connecting various combinations of primary and secondary 
windings in SERIES is another matter and no harm should 
result from nearly any combination, whether phased adding or 
subtracting, as long as the total current drawn from the 
combination doesn't exceed the transformer's capabilities..

Ken Gordon W7EKB