LMR400 SWR & Review Velocity Factor & Current to Voltage Ratios Along Antenna Feedline - Frequency

On slide 22 the formula with 57.4 V / 1.74 A should be 33 Ohms, it shows 55 which is incorrect sorry about that just saw it. One of the things I need help on is understanding Velocity Factor, in this video I attempt to give my understanding of what Velocity Factor is and what it means to me.

I’m in the process of reviewing the coax for my station which is DX engineering LMR400 MAX. I hope if there’s things, I’m missing please let me know I really enjoy the interaction and learning from all the experienced HAM’s.

From what I have determined there is a transformation that occurs and ½ and ¼ wave intervals, this is of coarse based on the transmit frequency, the velocity factor of the coax and the impedance at the base of the antenna. Since RF travels at the speed of light in open space, the wavelength can be calculated and the distance at ½ and ¼ wave is used to build both dipoles and ground plane antennas.

With the use of the Velocity Factor this is an index reference the “c” the speed of light that radio waves travel in an open space. Radio waves travel at 300,000,000 m/s, meaning that if you transmit from earth to the moon which is 384,000,000 meters away it would take your radio signal about 1.2 seconds to reach the moon.

From a safety aspect this ½ and ¼ wave transformation that occurs can result in some very high voltage and currents along the feed line and deepening on the frequency and Velocity factor it is possible to predict where this high point will be along the coax.

One thing I’m looking is I suppose it’s possible to cut an exact ¼ coax and create a transformation that might be more agreeable with your radio; however, the swings are still occurring in the coax and this results in heat so I’m not sure if this really solves any problems.

Thanks very much. I really appreciate everyone feedback.

Видео LMR400 SWR & Review Velocity Factor & Current to Voltage Ratios Along Antenna Feedline - Frequency канала West Texas Video Gates (KI5JUF)