G3>According to QST for September 1996, the recent version of the Autek
G3>instruction manual gives a formula on Page 10 for determining R +/- jX,
G3>which isn't in my older manual.
G3>Please could somebody let me know the details?
G3>73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
G3> 'In Practice' columnist for RadCom (RSGB)
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Dear Ian,
Attached is a BASIC program implementing the formula. It has some
problems. One doesn't always know if the reactance is capacitive or
inductive. It does calculate the correct value as far as I can tell.
You can always determine if the reactance is capacitive or reactive by
sweeping the frequency and seeing if you are above or below resonance as
determined by minimum Z. If you are above the resonance frequency it is
inductive (+X) and - X if you are below -- assuming resonace isn't too
far from your freq of measurement and there are no traps/lumped
constants in the ant.
5 CLS
10 INPUT "Z=",Z
20 INPUT"SWR=",SWR
30 R =(2500+Z*Z)*SWR/(50*(SWR*SWR+1))
40 IF Z >R THEN X=SQR(Z*Z R*R) ELSE X=SQR(R*R Z*Z)
50 PRINT "Z=";Z
60 PRINT "SWR=";SWR
70 PRINT "R=";R
80 PRINT "X=";X
90 INPUT X$
100 GOTO 5
73 de Brian/K3KO
to: INT:G3SEK@ifwtech.demon.co.uk
cc: INT:TOWERTALK@CONTESTING.COM
Vance Net Inc
End Of Message
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