[Kenwood] Kenwood IF-232C power supply connector polarity?

[Valentin 30IR976]

Hi all.I have a Kenwood IF-232C interface.I see the power connector for
13.8V.I have a power supply for this voltage, and have bought a
connector for the IF-232C connector's size, but would like to know the
polarity.The connector is one of the cilindric connectors, and would
like to know if the central conductor is + or - voltage.Perhaps someone
here has a IF-232C, and could measure and tell me the exact polarity...

73s de Valentin