...Down on line 8 he states " All the 50 ohm coax will be cut to the correct degree length using the MFJ with a Tee connector in parallel with a 50 ohm dummy load " That confuses me because about 9 lines further down he states " So we hook up a 1/4 WL length of coax based on the velocity factor, attach to the MFJ, short out the far end ... At this point I am wondering what happened to the 50 ohm dummy load?? Can I just hook up the coax, short it, read the freq at low swr, and go on from there without using the 50 ohms in parallel.
For a quarter wave line you would use the 50 ohm load in parallel with it. Cutting the
stub for minimum SWR makes it an electrical quarter wavelength. Without the
50 ohm resistor the SWR would be (theoretically) infinite for any stub length.
For other length stubs you can put them in parallel with the 50 ohm resistor and
trim them for a particular reactance value.
You need the 50 ohm load in parallel to center the measurements close to 50 ohms
where the analyzer is most accurate.