Phasing dots on Minicircuits ADTL1-4-75 RF transformer

[rfengg]

The phasing dots on the Minicircuits ADTL1-4-75 RF transformer is driving me bonkers 


As per their data sheet at https://www.minicircuits.com/pdfs/ADTL1-4-75.pdf , the phasing dots on this transformer have both dots shown on the same winding.........what exactly does this mean?

Usually the phasing dots on a transformer give information on the winding direction of the coils , but what do two dots on the same winding mean?

[ArthurDent]

It all depends on the design and what the transformer is used for. Here are some examples. 

[Bud]

This is a transmission line transformer and the dots mark primary and secondary terminals which are in-phase. If you swap the secondary terminals your output voltage will be 180 degree out of phase vs input voltage. Note that there is no galvanic isolation in TL transformers between input and output. You should know where and how to use them.

[ArthurDent]

Here's another picture with the phasing dots on the same winding. Google 'balun' and 'unbalanced to balanced'.