it's really hard to find information and pictures of this thing because HP has since reused the part number for a printer, but i think it's a design from the mid-60s or maybe very early 70s--it's not tube-based, but it's from a time period where "fully transistorized" was a selling point
-F
https://www.ebay.com/itm/184216346310?hash=item2ae4265ec6:g:~tUAAOSwbIZcTFMl thinking about this bit of equipment in our lab, super reliable useful thing and not even loud at all like our other high voltage power supply is
that's a ridiculous price on the ebay listing though, we got ours for like $300 plus like $50 shipping (it's a really heavy thing)
-F