>
> > David asks:
> >
> > >Is this because once the energy is lost (gone as heat or radiated by the
> > >pre-antenna components) there is no longer anything stimulating a
> mismatch
> > >at the antenna?
> >
> > No, it is because very high, many, many dB of return loss translates
> > to nearly a perfect impedance match through out the system carrying
> > the RF energy. It "means" the reflected power is many, many dB below
> > the forward power on the line, hence a very high loss is suffered by
> > the return power, get it?
> >
> > I can give you the timing of all this if you are interested; consider a
> > 30 wpm CW "dit": lasts about 43 milliseconds. Several reflection/
> > re-reflection pairs in 100 feet of typical coax transmission line
> > are all over and done with in only 3 or 4 microseconds! So neither
> > you nor the guy on the rcv'g end can possibly hear, nor can the
> > rigs amateurs use, possibly tell anything about this slightly later
> > radiated energy. The "dit" tone, after all, is 43,000 times
> > longer in time duration! You will never know that these
> > reflection phenomena are occuring, nor will your rig.
> >
> > All perfectly clear now, I'll bet, yeah, right! 73, Jim, KH7M
>
> Actually, much clearer!
>
> So the conclusion becomes, if we grant that loss issues will vary greatly,
> reflected energy due to mismatch is not inherently bad.
>
> Would you say that the issues now center around:
> 1. System loss.
Yes, but it's a composite of the several items that should be addressed
separately.
> 2. Misdirected radiated energy prior to the antenna.
Minor - you would have to have a mighty leaky setup for this to be
significant.
> 3. Strange loads imposed on the antenna.
Eh? I think you mean imposed "BY" the antenna on the feedline, creating a
non-unity VSWR. Yes, in that case.
> 4. Strange loads presented to the TX (presumably mitigated by a tuner).
Yes, this can upset the system and incurs some loss. Usually, this isn't
a problem.
> 5. Harm to components designed for 1500 watts perhaps exposed to bursts way
> over
> that.
The components are NOT subjected to power greater than that output by the
transmitter finals. High VSWR results in points where voltage is higher
than in a flat system and where current is higher than in a flat system,
but the power does not go up and down. The impedance is changing - an in
a system with constant power, that means the voltage and current must
change instead.
> Thanks for helping! 73, DavidC AA1FA
73, Ward N0AX
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