B738/9 Wake Turbulence Category
Having controlled in an ICAO state where there were numerous B738's operating - we never received from our regulator/CAA/ICAO any documents/instructions requiring us to provide more separation behind a B738.
We also had DH8C's operating there, and they together with the B738's were both treated as Medium wake turbulence category aircraft...
I honestly do not know about the B739's...