Can someone please explain, given a fixed impedance load (say 600 ohms), how raising the voltage of the source to several hundred volts affects matching efficiency?
IOW, in gerneral, as the voltage of an applied AC signal increases does impedance matching become progressively less of a concern? If so, why?
I am looking at the 1KHz to 1MHz bandwidth.
Tim Esser
"Tim Esser"
** What makes you imagine it has any effect on efficiency ? ** Impedance matching ( equal source and load ) is rarely ever a concern - as it is so wasteful of power.Your mysterious Q is impossible to answer unless you supply the context where this idea has arisen.
...... Phil
Impedance matching ensures that the maximum amount of power is deliverd to the load for a given output impedance. This property is not a function of voltage. However, in circuits involving transfer of large amounts of power, the major concern is power dissipation at the source, and impedance matching is usually not important. Impedance matching in the frequency range you're interested in would be a concern only if reflections (ringing) at the load are a problem.
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Since you are implying a linear load, impedance matching has nothing to do with signal level.
The usual concern with raised voltages is that the things you apply them to may not be rated at eg 600V, and the insulators in the coax, or whatever you're using, break down (ie sparks, etc).
There is a (DC) ohmmeter colloquially called a "Megger" used to measure resistance in mains-powered circuits. It does this at several hundred volts, to test the insulation. Ie it is a micro-ammeter fed by a high voltage supply. It is remarkable how many objects you think of as insulators turn out to have significant conduction due to dirt on their surface, etc at these voltages.
I can't answer the question as I don't know, but as mentioned above I'd be significantly concerned about components, cables etc blowing up when subjected to more then their rated voltage. Apart from mains electricity
- where obviously you use a much lower impedance than 600 ohms - I don't know where you'd use high voltage AC, except possibly when discussing an ariel where the voltage along it can get quite high due to standing waves.
-- Nemo
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