Version 4
SHEET 1 968 680
WIRE 320 64 -16 64
WIRE 400 64 320 64
WIRE 544 64 480 64
WIRE 864 64 544 64
WIRE -16 128 -16 64
WIRE 320 128 320 64
WIRE 544 128 544 64
WIRE 864 144 864 64
WIRE -16 256 -16 208
WIRE 320 256 320 208
WIRE 544 256 544 208
WIRE 864 256 864 224
FLAG -16 256 0
FLAG 320 256 0
FLAG 544 256 0
FLAG 864 256 0
FLAG 320 64 In
FLAG 544 64 Out
SYMBOL voltage -16 112 R0
WINDOW 123 24 124 Left 2
WINDOW 39 24 152 Left 2
SYMATTR Value2 AC 2
SYMATTR SpiceLine Rser=50
SYMATTR InstName V1
SYMATTR Value ""
SYMBOL res 336 112 M0
SYMATTR InstName R1
SYMATTR Value 57
SYMBOL res 528 112 R0
SYMATTR InstName R3
SYMATTR Value {R3}
SYMBOL res 384 80 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R2
SYMATTR Value {R2}
SYMBOL res 848 128 R0
SYMATTR InstName R_load
SYMATTR Value 50
TEXT -40 328 Left 2 !.ac oct 1200 100k 100meg
TEXT -40 360 Left 2 !.net I(R_Load) V1    ; for S-parameters
TEXT -80 -48 Left 2 ;; Calculator: https://www.qrp4fun.de/de/s5_01.htm\n; https://www.qrp4fun.de/de/s5_02.htm
TEXT 232 416 Left 2 !.step param R2 list 394.27 430\n.step param R3 list 17.34 22