> -----Original Message-----
> From: Tom W8JI [mailto:w8ji@w8ji.com]
> Sent: Sunday, October 15, 2006 4:17 AM
> To: Gary Schafer; 'AMPS'
> Subject: Re: [Amps] "10 Meter Ban" to be lifted ...
>
> > There was no limit on the peak envelope power we were
> > allowed to run; only a
> > limit on the average power as read on the plate meters.
> >
> > Peak envelope power can range from 5 to 10 times or
> > greater than the average
> > power we see on the plate meter with voice.
>
> OK, I see your point. Good point Gary and one that almost
> everyone misses.
>
> Conventional thought is the peak to average power ratio is
> only about 2:1. While that may be true for processed speech
> (even through ALC), it isn't true for unprocessed speech.
>
> So technically, using the meter response dictated by early
> FCC rules, we could run 10kW PEP input or more on occasional
> voice waveform peaks without making the meter exceed the
> legal 1000 watts indicated input on suppressed carrier phone
> transmissions.
>
> While the FCC increased carrier mode power like RTTY, FM,
> and CW it decreased peak power and average power of AM and
> peak power of unprocessed or lightly processed SSB.
>
> My only addition to that is the very short duration peak
> doesn't mean much for communications, so we didn't lose much
> in that way (except on AM). Anyone using processing already
> restricted the peak-to-average ratio (which also increases
> communications effectiveness) and would not have seen such a
> dramatic reduction in peak power. In other words the peak
> didn't mean that much anyway when the speech was processed
> to improve communications effectiveness.
>
> Good point Gary.
>
> 73 Tom
>
Hi Tom,
Back then most people did believe that PEP was 2x the average power which
was true for a two tone test but not with voice. Even then most
manufacturers published specs on amplifiers and radios quoted pep as 2x
average power too. Several of them even published that an amplifier that
would make 1 kw dc input on cw would automatically produce 2 kw pep! No
wonder most were confused.
Also I think most people believed that with 1 kw average input as the legal
limit that meant that 2kw pep was also the legal limit because of the
perceived 2:1 ratio.
In real practice we did not loose too much as most hams did not have
amplifiers capable of any real power as they thought they did. Most that ran
their amplifiers at the 1kw average input level were severely overdriven in
order to reach that power level as they were not capable of high enough pep
levels.
If one talks the power up to where the alc just starts to show and watch the
plate current meter, it is surprising just how low the average power is.
Even running a moderate amount of alc the average power is pretty low.
I agree that average power is what really counts.
73
Gary K4FMX
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