For example: Agilent E4440A or Anritsu 68369
Power Supply
TDK-Lambda LLS6040
LLS6040 40 V, 4.0/4.0/3.8/3.1 AMP, DC Programmable Power Supply

Manufacturer: TDK-Lambda
TDK-Lambda LMEE12
LMEE12 12 + 5% V, 21/19/16.1/13.2 AMP, DC Regulated Power Supply

Manufacturer: TDK-Lambda
TDK-Lambda LPD425AFM
LPD425AFM 250 V, 0.13 AMP, Dual DC Regulated Power Supply

Manufacturer: TDK-Lambda
TDK-Lambda LPT-7202-FM
LPT7202FM 20/ 7 V, 5/ 1.5 AMP, Triple Output Power Supply

Manufacturer: TDK-Lambda
Power 10 P66C-60330AB
0 - 60V, 0 - 330A, 20kW DC Power Supply. Digital Display. Requires 200-240V AC Three Phase Input

Manufacturer: Power 10