[UK-CONTEST] Quest for QRO

[g3ory at lineone.net]

Paul,

I think Ian GM3SEK has said pretty much all there is to be said.  Just 
one final thought: you said

>>
A 150w i/p class C AM transmitter gives a 100w o/p CW signal.
A 400w o/p PEP SSB transmitter gives a 400w o/p CW signal -
Proof: feed the microphone socket with an audio tone to
get your CW - or just whistle :-)

.....but not with 150W dc input!

73 Bob

>----Original Message----
>From: pokane at ei5di.com
>Date: 22/02/2009 23:30 
>To: <uk-contest at contesting.com>
>Subj: Re: [UK-CONTEST] Quest for QRO
>
>----- Original Message ----- 
>From: <g3ory at lineone.net>
> 
>> I think this is a bit unfair. I don't recall that anyone
>> ever claimed  that a 150W dc input Class C AM PA would
>> give 400W pep of ssb out.  This is not the basis of
>> equivalence that was or should have been adopted.
>
>I believe that's exactly what happened, intentional or
>otherwise.  The fiddle was to confuse Peak Instantaneous
>Power with Peak Envelope Power (PEP).
>
>150 watts DC input (Class C AM) typically gives 100w o/p.
>At the instantaneous 100% modulation peak, the waveform
>voltage is doubled and therefore the instantaneous peak
>power o/p is 400w.
>
>That's why those who should have known better, and perhaps
>did, argued that that 400w PEP o/p on SSB was required to
>give the same o/p voltage as fully-modulated 150w i/p on AM.
>
>It was a very successful con job because, as is now accepted,
>PEP is effectively the same as RMS - power measured over time 
>(one or more RF cycles) - rather than power calculated at
>the instant of peak modulation.
>
>A 150w i/p class C AM transmitter gives a 100w o/p CW signal.
>A 400w o/p PEP SSB transmitter gives a 400w o/p CW signal -
>Proof: feed the microphone socket with an audio tone to
>get your CW - or just whistle :-)
>
>73,
>Paul EI5DI
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>





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