Philips PM 5191 Operating Manual page 33

3.5.2.2.
Controls/Indicators
LEVEL
Vee +i-
Vpp dim Vrins
A LEVEL - STEP +
Rear Connections
E 3-5
Function
Keyboard (12) to select the modulation mode
internal: INT
external:EXT
Keyboard (13) to set the frequency.
Keyboard (15) to select the wave form.
Fuse (19).
Mains socket (20).