Sub-menu "Velocity Factor"

[oh3uu]

Version 655 has a Sub-menu "Velocity Factor" in the menu "Setup".
I can't find any info in which function this new menu takes effect.

[w0qe]

I believe the Velocity factor menu in the setup menu is really unnecessary. What it does is to set the initial VF value in the "distance to Fault" and "Refer to Antenna" modes in the "Function Menu". However you can override the delault VF value so having an initial value is not really necessary. It may also be used elsewhere but I'm not sure. It is NOT used to set the default VF in the "Line Extension" menu which defaults to VF=1.

I don't use this feature of the AIM4170 so I may have missed something but I have played with every featur. I always calibrate to the end of a piece of cable, using the "Custom Calibration" which is more accurate and then do a small amount of +/- "Line Extension" if needed to include or exclude some adapters. Care needs to be taken to do a calibration with more points if you intend to measure impedances that are far from 50 ohms when the external cable is more than an electrical quarter wavelength at the measurement frequency. This is because a short at the end of a quarter wavelength is seen as an open etc. and any analyzer has a tougher time measuring zero or infinity compared to numbers nearer to 50 ohms. Calibrations and special cables or test fixtures can be saved and reused without doing subsequent calibrations which is very convenient.

Bob included many features in the AIM4170 that are not classis "Network Analyzer" features such as "Distance to Fault" (this is a time domain reflectometer feature). I'm sure some folks use these features regularly and others never do. While it is nice to have the feature it often is more confusing initially.

73, Larry W0QE

[w0qe]

Please change my spelling error in the last paragraph "classis" to "classic".

W0QE