5 CLS
10 PRINT "This program calculates optimum parallel-feedline"
15 PRINT "lengths (also worst case feedline lengths to avoid)"
20 PRINT "given dipole length, frequency, and feedline velocity"
21 PRINT "factor for dipoles that are at least 2/5 wavelengths"
22 PRINT "long at the lowest frequency of operation": PRINT
30 PRINT "This program assumes a 1:1 current-balun and doesn't"
31 PRINT "work for N:1 baluns where 'N' is not equal to 1.": PRINT
33 PRINT "If the feedline velocity factor is unknown, a good"
34 PRINT "average approximation to be entered is 0.9"
35 PRINT "NOTES: For 300 ohm transmitting ladder-line, VF = ~0.8"
36 PRINT "For 450 ohm ladder-line and 300 ohm TV twinlead, VF = ~0.9"
37 PRINT "For Open-Wire feedline, VF = ~0.95": PRINT
38 PRINT "Enter <Ctl-Break> to exit this program at any time.": PRINT
39 PRINT : INPUT "Enter Dipole Length in Feet: ", diplenft
40 PRINT : INPUT "Enter Frequency in MHz: ", freq
45 PRINT : INPUT "Enter Velocity Factor, 0.8 < VF < 1.0 : ", vf
51 length = 375 / freq
55 IF length > diplenft THEN
56 PRINT : PRINT "********** Warning! **********": PRINT
57 PRINT "Dipole Length Too Short. For This Frequency"
58 PRINT "It Needs To Be Longer Than"; length; "Feet"
59 PRINT : PRINT
60 GOTO 39
61 END IF
70 LLWL = 984 * vf
90 dipwl = diplenft / (936 / freq)
100 IF dipwl < .5 THEN dipwl = dipwl + 1
110 IF dipwl < 1.5 THEN GOTO 140
120 IF dipwl > 1.5 THEN dipwl = dipwl - 1
130 GOTO 110
140 fedlinwl = .25 - (TAN(2.5 * (dipwl - 1))) / 12.02
150 fedlinft(0) = (LLWL / freq) * fedlinwl
160 FOR i = 1 TO 7
170 fedlinft(i) = fedlinft(0) + i * ((LLWL / 2) / freq)
180 NEXT i
190 PRINT : PRINT "Optimum Lengths: Imax points (Current Loops) at"
200 FOR i = 0 TO 7
205 IF fedlinft(i) < 150 THEN PRINT fedlinft(i),
210 NEXT i
220 FOR i = 0 TO 7
230 fedlinft(i) = fedlinft(i) + (LLWL / freq / 4)
240 NEXT i
250 PRINT : PRINT : PRINT "Lengths to Avoid: Imin points (Current Nodes) at"
260 FOR i = 0 TO 7
265 IF fedlinft(i) < 150 THEN PRINT fedlinft(i),
270 NEXT i
280 PRINT : PRINT : GOTO 39
290 END