[Amps] SWR and amplifiers

[Vic Rosenthal]

The 100 watts is not lost in the transmission line. It is not 'lost' at all. If you had a perfect transmission line, there would be no additional loss in a line with a high SWR over a matched line.

Vic 4X6GP 

> On 25 May 2017, at 4:59, Bill Turner <dezrat at outlook.com> wrote:
> 
> According to Ron, K4INM, (original post below) my hypothetical
> transmitter is putting out 1000 watts but only 900 is actually
> radiated into space. The 100 watt difference is lost in the
> transmission line. Correct?
> 
> OK, lets suppose I have a superconductive transmission line,
> cryogenically cooled conductors with a vacuum dielectric, zero loss.
> The SWR is still the same, reflected power is the same, but now where
> does the lost power go? Would my SWR meter still show 1000 forward and
> 100 reflected?
> 
> 73, Bill W6WRT
> 
> **********************************************************************************
> 
> Here is Ron's original post:
> 
> Do not worry about the confusion, it is all too common among HAMs
> even
> highly seasoned ones, to get this wrong.
> You will soon here the opposite of the following here, but they are
> wrong.
> 
>  The amplifier outputs 1,000 Watts.
> 
>  900 Watts minus "transmission line loss" X 1.0 is radiated.
> 
>  100 Watts are reflected by a line to "load mismatch" back to the
> "generator" the amplifier (the only cause of any SWR) or reflected
> power.  This power when it reaches the (generator" the amplifier)
> finds
> a source impedance of under one Ohm, so it is reflected back up the
> transmission line experiencing a "transmission line loss" X 2.0 where
> 90% of that power is radiated.
> 
>  10 Watts are reflected by a line to "load mismatch" back to the
> amplifier finding a source impedance of under one Ohm, so it is
> reflected back up the transmission line experiencing a "transmission
> line loss" X 2.0 where 90% of that power is radiated.
> 
>  1.0 Watts are reflected by a line to "load mismatch" back to the
> amplifier finding a source impedance of under one Ohm, so it is
> reflected back up the transmission line experiencing a "transmission
> line loss" X 2.0 where 90% of that power is radiated.
> 
>  0.1 Watts are reflected by a line to "load mismatch" back to the
> amplifier finding a source impedance of under one Ohm, so it is
> reflected back up the transmission line experiencing a "transmission
> line loss" X 2.0 where 90% of that power is radiated.
> 
>  100% of the generated power is either radiated or turned into heat
> from the transmission line (and balun + antenna wire) losses.  (mostly
> resistive)
> 
>  None of the forward power stays in the amplifier, although the
> reflected power does change the "loading" of the amplifier, changing
> it's operating conditions, from what it was with a pure reactive-less
> resistive load.
> 
> -- 
>  Ron  KA4INM - Youvan's corollary:
>                Every action results in unwanted side effects.
> 
> 
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