OK... here is _minimal_ tech answer... no formulas, no confusion.
SWR is a wave. It does really not exist per say. It is just an envelope
modulation on the carrier related to group delay, medium velocity and other
thousand reasons. Actually SWR is a mathematical SYMBOL for the mismatch
ratio between a source and load.
SWR caries energy. As any energy it must be transformed in an other form
otherwise, as
with any other form of energy, if you remove it's source it will still
remain alive and well...
This is not quit what happens, no?
What REALLY happens is that SWR is renewed every time by the bounce back of
the antenna side and killed a bit (or DISSIPATED if you will) when is
bounced of the transmitter output side. Please observe I do not talk about a
tuner but the generator (transmitter) output. The net effect on the antenna
side is that sometimes when the bouncing coincides in phase with the
incident wave you will have a SWR GAIN :) i.e. you will radiate a bit more
:) Isn't this cool ?
On the transmitter side, SWR hits a hard rock. It has no where to go so it
bounces back BUT a little bit of its energy is released into the rock (the
transmitter output) and here it gets converted in currents and voltages that
ultimately are converted in heat. A small amount of heat. However, heat is
cumulative. Thermal energy has a long inertia and if not removed faster than
the accumulation then you have a thermal runaway or, in nuclear jargon, a
thermal meltdown :)
Recognizing this fact ( finally) some manufacturers have started to put fans
into their
reactance converters (antenna tuners). Slowly but surely, we realize that
SWR in last instance, DOES generate heat.
Hope this clarifies the "technical" aspect of this thread that, I hope will
end here.
===================================
If we can accept the notion that GUNS are
the killers and not the people, why is it that
we can not accept the idea that CARS are
the speeders and not the drivers?
Alex, trying to understand the world around.
==================================.
----- Original Message -----
From: "Tom Rauch" <w8ji@akorn.net>
To: "alex" <alex@sandlabs.com>
Sent: Wednesday, December 12, 2001 8:48 AM
Subject: Re: [TowerTalk] ++ High SWR and Modern Transceivers
> > I think this thread should have been called "Perpetum Mobile" :)
> > While I am a strict adherer to the old saying, "Never smarten a dummy"
> > I will make an xception now. First, for the record, here is what I
> > said:
>
> If you can write a trechnical response without insults, I will read it.
> Otherwise get lost.
> 73, Tom W8JI
> W8JI@contesting.com
>
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