This information is edited from a repost of an acig.org forum post by mrdetonator:
http://www.secretprojects.co.uk/forum/index.php/topic,25.msg59.html#msg59
“СТРОБ/ВЫК” Switch
In the position “СТРОБ”, target selection impulses (lines) for the RL are generated on the SEI. In the position “ВЫК”, target selection impulses (lines) for the IRST are generated.
“УС Т” Knob
Amplifies video-signal from the IRST, used when jamming is encountered.
“УС” Knob
Amplifies radar signal in the “БСВ-ΔH, МВ” used when jamming is encountered.
“ΔH” Knob
Antenna scan zone presets in elevation(+6º/-4º).
The antenna scan zone/radar range-finder is also controlled through the "ПОМ" knob located on the throttle
"ЗОНА Р ,СТРОБ Т, СБРОС" Joystick/Switch
Controls radar scan zone in azimuth, controls target selection impulses (lines) for IRST in azimuth and elevation.
The "СБРОС" switch position is used to cancel the RL and the IRST lock.
АПХ/ППХ Switch
Serves to switch-on the radar protective circuits against active/passive jamming.