Measure Velocity Factor, An Alternate Method (050)

In this video I will show you an alternate method of measuring the Velocity Factor of a coaxial cable assembly that will lend itself very nicely to creating your own Band Reject Filters or Stub Matches using coax.

I show this using BNC connectors, but it can be modified to use any implementation that fits your application.

SPEED OF LIGHT VALUES
11802.85E6 inches/sec
29979.24E6 cm/sec

Time Markers for Your Convenience
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00:05 Introductions
01:21 The Setup
01:22 Prerequisites
01:48 Tour of the Hardware Setup
02:47 The Process: Introductions & VNA Initial Setup
03:29 STEP 1: Measure Your Assembly
04:00 STEP 2: Calculate fo for 1/4 wavelength
04:55 STEP 3: Set the Center frequency and Span on the VNA
05:52 STEP 4: Sweep and determine the actual fo
06:28 STEP 5: Set the VNA Center frequency and Span
07:02 STEP 6: Do a complete "Through" VNA Calibration
08:04 STEP 7: Sweep the assembly again and get the actual, precise fo
09:06 STEP 8: Calculate the Velocity Factor
10:03 Final Comments and Toodle-Oots
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[StephenKangas]

Can this technique be used to measure the VF of insulated wire used for antennas? I am planning on cutting several End Fed Random Wires for use with a 9:1 unun I recently made. As you may know, there's nothing really "random" about EFRW, especially when trying to do many ham bands. There are so many lengths to avoid, especially when trying to cover the 60m band in the mix with the usual suspects. A difference in as little as one foot can be bad. SO, I'd like to adjust the table of EFRW lengths that assume 100% uninsulated copper wire and recalculate for my silicon jacket insulated copper wire. Your video removing some braid from coax suggest it would work for the entire stub being unshielded but insulated wire? My bet is there are others out there using various other wire gauges/insulations whose inquisitive minds want to know.