Thanks for the replies. I have not looked into this type analysis for some 20 years. I still have my Terman reference!
The value/unit is specified in the Spice 3f5 help pages. I used the value/foot specifications for Belden 9914 Coax and specified the length in feet. I added the center conductor and shield resistances. .model rg_8u LTRA (len=3.2808399 l=.065uh c=24.8pf r=2.3)) v1 1 0 dc 0 pulse 0 1 1ns 0.1ns tran 1p 15n I see v(1) starting to rise at 1.010000e-09 and v(3) starting to rise at 5.204000e-09 sec or a transmission time of 4.194000e-09 seconds. The length is 1 meter. 1/4.194000e-09 = 2.384359e+08 meters/sec or 79.4% C (3e8) JPL in DE405 gives 2.9979245799999998E+08. 4.194000e-09/3.2808399 = 1.278E-09 sec/ft delay. The spec sheet says velocity of propagation 82% and nominal delay 1.24ns/ft. v1 1 0 dc 0 ac 1 sin 0 1e6 ac lin 1e4 1e8 1e9 plot 10*log((v(3)*o1#i2)/(v(2)*o1#i1)) The ripple I see in the 300 to 900mHz area of the plot is 60mHz. This agrees with the specs. The .02db ripple amplitude. How do I calculate this? ac lin 1e5 1 1e9 plot 10*log((v(3)*o1#i2)/(v(2)*o1#i1)) The losses do not agree with the mfg datasheet. tomdean _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user