On Wed, Dec 14, 2022 at 10:12 AM, G8HUL wrote:
Most Pas are not 50 ohm, they are designed to give a specified power 'into* a 50 ohm load.
Jeff,
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That's right, impedance matching is necessary for sources that can only deliver a small amount of electrical power and whose power is to be passed on as comprehensively as possible. Such weak sources are, for example, antennas. With linear sources and sinks, in the best case only half of the available power is actually radiated; the efficiency is then 50 %. The other half is lost as power dissipation in the internal resistance of the source.
Electrical energy sources, e.g. a power station, but also a large PA - whether audio or high frequency - are therefore not designed for power matching, but for voltage matching (i.e. low source resistance); their nominal power would therefore be exceeded long before any (theoretical) power matching.
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Martin
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Ho-Ro