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![]() Richard Fry wrote: "Roy Lewallen" wrote The problem is that the idea of "reflected energy" turning the plates hot is so easy to understand, that people aren't willing to abandon it simply because it isn't true. _____________ But reflected energy/power does exist. For an easy example, such reflections are evident in the picture seen on an analog TV receiver when the match between the transmit antenna and the transmission connected to it is bad enough. In analog TV transmit systems with a typical 500+ foot length transmission line from the tx to the antenna, a 5% reflection from a far-end mismatch can be quite visible, showing as a "ghost" image that is offset from the main image as related to the round-trip propagation time of the transmission line. Richard, The round trip time on the transmission line is 1uS+, and the period of the highest modulating frequency is 0.2uS, so transient performance of the line is very important. Run the numbers on typical ham SSB telphony where the rtt is more like 0.2uS+ and the period of the highest modulating frequency is 300uS, is it any wonder transient performance isn't critical. So, if a solution in the steady state solution doesn't degrade the modulation, why complicate matters with pretend partial time domain solutions. It is half baked thinking in both worlds that drives the thinking that reflected power *must* be dissipated in the anode. There is no doubt that under load end mismatch, there is a reflected wave on the transmission line, and there is no doubt that under some conditions, the anode dissipates more power, and they may be correlated, but the simplistic explanation above that is commonly touted is BS. Owen |
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