Dreamstation 2 DC Power Connector ?

[GWild]

Anyone know the specs of the Dreamstation 2 CPAP DC power connector?  

Trying to find an adapter or cable from a generic 5.5x2.5mm female battery source to the CPAP ... and having issues finding anything that actually fits. Even a 5.5x2.1mm to CPAP would work.

[GWild]

Following up:

Measuring what I have seems to be a 0.7mm pin, with a 5.3 mm barrel ID and 7.4 mm barrel OD.

Hours of searching, all I have so far is guess work: the CPAP seems to have a "7.4 x 5.0 mm" connector, per one 'standard' naming convention; or "7.5 x 0.7 mm" per another convention.

[StratCat48]

Not sure if this chart within the link below may offer some clues. For the 7.4mm OD barrel size it shows some possible usages for that size

https://en.wikipedia.org/wiki/Coaxial_power_connector