I own a Heathkit IP-17 which had identical rating to the HP-23 that you
have. For higher amounts of current, I cobbled together the combination
of a Variac, a salvaged TV set power transformer, bridge rectifier, and
filter capacitors to do the job.

Although unregulated, it performed its job well for many years.

Sorenson and other firms manufacture large, regulated power supplies
that will do arguably better work, but even used these generally
command a price of several hundred dollar, compared to the $30 or so
that I invested in my home built variable voltage supply.

Try periodically checking on eBay.

Good luck. Harry C.