[Amps] SWR and amplifiers

Alek Petkovic vk6apk at bigpond.com
Wed May 24 22:12:20 EDT 2017


No. Read it again. Ron was saying that 100% of the 1000 Watts, minus the 
compounded resistive losses is going out into space. Those losses would 
NOT amount to 100 Watts of dissipation.

Therefore, with your superconductor feedline, as there are no resistive 
losses, 100% of the 1000 Watts will be radiated.

Google Kurt N Sturba. He explained it well, in his regular column in 
World Radio magazine. Just like Ron did, below.

73, Alek.
VK6APK

On 25/05/2017 9:59 AM, Bill Turner 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.
>
>    

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