"Frank" wrote in message
news:_Jchk.905$nu6.310@edtnps83...

"Frank" wrote in message
news:CDchk.904$nu6.498@edtnps83...
What doesn't seem to agree between theory and practice is that
measuring any "b" stub in parallel with the dummy load shows an
impedance of about R=11 and X=11, while on the smith chart this should
be R=11 and X=21 (obviously all at 70 MHz). Why it does measure right
alone and wrong with a coaxial "T" adapter and the dummy load in
parallel?
Of course in real life I'm assuming a Vf=0.88 for the cellflex cable
and checking measures with the analyzer.

What could be wrong?
Any hint is appreciated

PS the single shunt stub of 86.8 degrees calculates to 11.7 - j 21 ohms,
when in parallel with a 50 ohm load (At 70 MHz).

Frank

Hi Frank

My calculations indicate that the length of "A" (50 ohm coax) should be
close to 48.6 degrees between two identical open stubs with a 50 ohm
termiantion on the 50 ohm line when I use your 11.7 -J21 impedance. So, my
recommendation stands. Try a little shorter "A" if impedance match at 70
MHz is the objective.

Jerry