Good point Nigel. Back in the '60s I designed a video distribution amplifier for receiver video to tape recorders, O scopes and the like and I matched the input impedance to prevent reflections on the video line from distorting the signal. The output impedance of my amplifier was as low as I could get it, and it worked very well.
I did not design the output impedance to be 50 ohms, the impedance of the cable we used to distribute the video. I depended on the load to be 50 ohms resistive to prevent any reflection. On the other hand, the audio distribution amplifiers were not matched on the receive end. I also designed the output impedance of an audio amplifier to be as low as I could get it, and was able to switch multiple loads on the output without changing the level. The input impedance of the audio circuits was always 600 ohms or higher. The power distribution grid is more like the audio and video situation than the SWR problems we see at RF. 73 - Jim W5ZIT --- In [email protected], "Nigel Johnson" <[EMAIL PROTECTED]> wrote: > > Very interesting theory. I am teaching SWR at present to my third > year college students. Could be a good discussion point since they > have already studied power factor. However, SWR can exist with a > purely resistive mismatched load, so it needs a bit of modification to > take all into account. > > 73 > Nigel > ve3id >
