I’ve found some connectors that look close but have a center pin. The cable would need to be 8ft and support 19.5v, 16.9A and 330.0W.
The calipers say it’s 7.43mm outside and 5.2mm inside with no middle pin. I asked the power supply manufacture and they said it’s “11 X 7.4X 5.1mm”.
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I took a look through our system for some power barrel connectors and cables. Unfortunately, we have no cables with that size of connector, and it seems we only have one connector of 7.4mm OD x 5.1mm ID.
That would be PN: 102-5557-1-ND , which is a Jack, not a Plug.
If you can wire a plug and socket to 8 feet of wire, something like 12 gage copper, stranded,
then you can cut the existing cable, wire a socket on the power-brick and a plug
on the delivery end of the existing cable, and stick your 8 feet extension between those
Please do NOT do this with plugs that could be stuck in an AC wall socket… for obvious reasons.
It’s not all plugs and sockets that can handle 16.9 amps, but the 19VDC is safe for any insulated wiring
you could find.
Or, you could put the 8 foot extension cable not onto the low-V output of the power brick,
but the high-AC-voltage input side.