[Diplexers] ' Converted From Old Magazine Article 1982-2005 Bill Yotter
MAINWIN 44 36:CLS:PI=asn(1)*2:DIM TABLE(7):PRINT
PRINT"     Multi Order L/C Diplexer Filter":PRINT
PRINT"     Chebishev Filter Configurations"
PRINT"        Maximum Ripple =< 0.1 dB"
PRINT"        Reflection     => -40 dB":PRINT
PRINT"       1. Low & High Pass"
INPUT"       2. Band Pass & Stop ? ";A
INPUT"       Order 3, 5, or 7    ? ";ORDER
IF NOT((ORDER=3 OR ORDER=5 OR ORDER=7) AND (A=1 OR A=2)) THEN [Diplexers]
INPUT"       Impedance (3 loads) ? ";Z
IF ORDER=3 THEN TABLE(1)=1.5133:TABLE(2)=1.509:TABLE(3)=.7164
IF ORDER=5 THEN TABLE(1)=1.561:TABLE(2)=1.8069:TABLE(3)=1.7659:TABLE(4)=1.4173:TABLE(5)=.6507
IF ORDER=7 THEN TABLE(1)=1.5748:TABLE(2)=1.8577:TABLE(3)=1.921:TABLE(4)=1.827:TABLE(5)=1.734:TABLE(6)=1.3786:TABLE(7)=(.6307)
IF A=1 THEN GOSUB [LPandHP] ELSE GOSUB [BPandBS]
PRINT :X$=INPUT$(1):GOTO [Diplexers]
[LPandHP]
INPUT"       Cutoff frequency    ? ";FC
WC=2*PI*FC
PRINT:PRINT" *** Low Pass [Ls-Cp etc.] ***": PRINT
FOR N=1 TO ORDER STEP 2
TEST=TABLE(N)*Z/WC '  L(N)
GOSUB [EngNote]
LIN$=" L"+STR$(N)+TEST$
IF N=ORDER THEN [LPloop]
TEST=TABLE(N+1)/(Z*WC)
GOSUB [EngNote]
LIN$=LIN$+"   C"+STR$(N+1)+TEST$
[LPloop]
PRINT LIN$
NEXT N
PRINT:PRINT" *** High Pass [Cs-Lp etc.] ***": PRINT
FOR N=1 TO ORDER STEP 2
TEST=1/(TABLE(N)*WC*Z)
GOSUB [EngNote]
LIN$=" C"+STR$(N)+TEST$
IF N=ORDER THEN [HPloop]
TEST=Z/(WC*TABLE(N+1))
GOSUB [EngNote]
LIN$=LIN$+"   L"+STR$(N+1)+TEST$
[HPloop]
PRINT LIN$
NEXT N
RETURN
[BPandBS]
INPUT"       Low frequency       ? ";F1
W1=2*PI*F1
INPUT"       High frequency      ? ";F2
W2=2*PI*F2
PRINT:PRINT" *** Band Pass Section ***        con/res": PRINT
FOR N=1 TO ORDER STEP 2
TEST=(F2-F1)/(W1*F2*Z*TABLE(N))
GOSUB [EngNote]
LIN$=" C"+STR$(N)+TEST$
TEST=Z*TABLE(N)/(W2-W1)
GOSUB [EngNote]
LIN$=LIN$+"   L"+STR$(N)+TEST$+"   S & S"
PRINT LIN$
IF N=ORDER THEN [BPloop]
TEST=TABLE(N+1)/((W2-W1)*Z)
GOSUB [EngNote]
LIN$=" C"+STR$(N+1)+TEST$
TEST=Z*(F2-F1)/(W1*F2*TABLE(N+1))
GOSUB [EngNote]
LIN$=LIN$+"   L"+STR$(N+1)+TEST$+"   P & P"
PRINT LIN$
[BPloop]
NEXT N
PRINT:PRINT" *** Band Stop Section ***        con/res": PRINT
FOR N=1 TO ORDER STEP 2
TEST=1/(TABLE(N)*(W2-W1)*Z)
GOSUB [EngNote]
LIN$=" C"+STR$(N)+TEST$
TEST=(F2-F1)*TABLE(N)*Z/(W2*F1)
GOSUB [EngNote]
LIN$=LIN$+"   L"+STR$(N)+TEST$+"   S & P"
PRINT LIN$
IF N=ORDER THEN [BSloop]
TEST=TABLE(N+1)*(F2-F1)/(W2*F1*Z)
GOSUB [EngNote]
LIN$=" C"+STR$(N+1)+TEST$
TEST=Z/(TABLE(N+1)*(W2-W1))
GOSUB [EngNote]
LIN$=LIN$+"   L"+STR$(N+1)+TEST$+"   P & S"
PRINT LIN$
[BSloop]
NEXT N
RETURN
[EngNote]
I=0
WHILE TEST<=1 AND I<5
TEST=TEST*1000
I=I+1
WEND
IF I=0 THEN [NoEng]
DENOM$="munpf"
TEST$="= "+LEFT$(STR$(TEST),7)+MID$(DENOM$,I,1)+"  "
RETURN
[NoEng]
TEST$="= "+LEFT$(STR$(TEST),7)+"? "
RETURN