I've got a VLF transmission line with a possible impedance discontinuity 1000ft from the PA, so only a small fraction of a wavelength away, but the total transmission line length is significant relative to the wavelength. So my question is, do rules of an electrically short transmission line apply so that I can basically ignore this? It would make sense that no standing wave can develop in the portion of the line before the discontinuity, but do I need to worry about reflections at my PA output? Thanks!

 

It will change the impedance seen by the amp, so also probably changing the power output to some amount.

 

Thanks rjenkins. Is that the only effect? No reflected power at the PA?

 

How bad is the impedance mismatch?

 

A discontinuity a small fraction of a wavelength from the amp would have a similar effect to the same fault directly at the amp output.

If the fault is either a short or open circuit, then either near zero or infinite impedance at the amp, so a pretty high level of reflected power.

 

SgtWookie -
This is actually more of a hypothetical for now. I'm doing a splice job on an accidentally severed cable, so I'm thinking of "what ifs" if the splice job is done poorly.