I owned the Nobeltec radarPC also, same generation as yours, and VNS. Great software even by today's standards. But the radar is 10 year old hardware and is junk by today's standards. It might die next week. Don't put good money into it or limit your choices because of the legacy dome on your mast. You got plenty of use out of it and it doesn't owe you anything.

Plus you're limited to in-cabin viewing on a weather-sensitive PC. IMO radar belongs at the helm (on a swivel mount) using a weatherproof CP so it can augment your watch keeping from anywhere in the cockpit, in the worst conditions.

Newer digital radars use thinner cable and would be easy to thread through your mast, especially if you're going to have the mast-down for winter.

Now that I've said all that, you can probably get that radar to work with what Nobeltec recommended, but what high-definition radar options do they offer you for new radar interface if your old low-definition scanner dies? And what does that blue box cost?

I'd still recommend hi-def radar at the helm. I'm using broadband radar and would never go back to radarPC.