Version 4
SHEET 1 880 680
WIRE 592 0 240 0
WIRE 688 0 592 0
WIRE 592 16 592 0
WIRE 240 64 240 0
WIRE 480 112 288 112
WIRE 592 112 592 96
WIRE 592 112 560 112
WIRE 32 128 -64 128
WIRE 192 128 32 128
WIRE 592 144 592 112
WIRE 32 160 32 128
WIRE -64 240 -64 128
WIRE 688 240 688 0
WIRE 32 288 32 240
WIRE 64 288 32 288
WIRE 208 288 208 176
WIRE 208 288 144 288
WIRE 272 288 208 288
WIRE 336 288 272 288
WIRE 592 288 592 224
WIRE 592 288 416 288
WIRE 272 304 272 288
WIRE 32 336 32 288
WIRE 592 336 592 288
WIRE 208 400 208 288
WIRE -64 448 -64 320
WIRE 32 448 32 416
WIRE 32 448 -64 448
WIRE 192 448 32 448
WIRE 480 464 288 464
WIRE 592 464 592 416
WIRE 592 464 560 464
WIRE 592 480 592 464
WIRE 240 576 240 512
WIRE 592 576 592 560
WIRE 592 576 240 576
WIRE 688 576 688 320
WIRE 688 576 592 576
FLAG 272 304 0
FLAG 240 0 a1
FLAG 240 576 a2
SYMBOL Misc\\tetrode 240 112 R0
SYMATTR InstName U1
SYMATTR Value EL34N
SYMBOL Misc\\tetrode 240 464 M180
SYMATTR InstName U2
SYMATTR Value EL34N
SYMBOL Misc\\EuropeanResistor 16 144 R0
SYMATTR InstName R1
SYMATTR Value 100K
SYMBOL voltage 160 288 R90
WINDOW 0 -32 56 VBottom 2
WINDOW 3 32 56 VTop 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 39.5
SYMBOL voltage -64 224 R0
WINDOW 3 -68 251 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value SINE(0 79 1K)
SYMATTR InstName V2
SYMBOL Misc\\EuropeanResistor 16 320 R0
SYMATTR InstName R2
SYMATTR Value 100K
SYMBOL voltage 432 288 R90
WINDOW 0 -32 56 VBottom 2
WINDOW 3 32 56 VTop 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value 470
SYMBOL Misc\\EuropeanResistor 576 96 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R3
SYMATTR Value {x}
SYMBOL Misc\\EuropeanResistor 576 448 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R4
SYMATTR Value {x}
SYMBOL res 672 224 R0
SYMATTR InstName R5
SYMATTR Value 3.4K
SYMBOL ind2 576 0 R0
SYMATTR InstName L1
SYMATTR Value 2.64
SYMATTR Type ind
SYMBOL ind2 576 128 R0
SYMATTR InstName L2
SYMATTR Value 1.36
SYMATTR Type ind
SYMBOL ind2 576 320 R0
SYMATTR InstName L3
SYMATTR Value 1.36
SYMATTR Type ind
SYMBOL ind2 576 464 R0
SYMATTR InstName L4
SYMATTR Value 2.64
SYMATTR Type ind
TEXT -136 568 Left 2 !.tran 0 10m 8m 1µ
TEXT 544 -32 Left 2 !K L1 L2 L3 L4 0.99
TEXT 168 616 Left 2 !.inc Tubes.cir
TEXT 376 616 Left 2 !.step param x list 100 1000