On Sat, 02 Oct 2004 21:48:00 +0100, Paul Burridge
wrote:

On Thu, 30 Sep 2004 09:41:43 -0700, Bill Turner
wrote:

Peak-to-peak voltage has no meaning when computing power. There is no
such thing as peak-to-peak power.

Why not? p-p power is essentially "peak envelope power" isn't it? Are
you saying there's one rule for RF and another for audio??

The definition of peak envelope power (PEP) is: "The average power
contained in one RF cycle at the crest of the modulation envelope".
(note that the definition says "AVERAGE power" not RMS power) This is
from the FCC definition.

If your SSB transmitter puts out 1500 watts pep with voice it also
will put out 1500 watts with full carrier inserted and no modulation.
(assuming power supplies do not sag)

Same maximum rf power with the carrier only difference is that with
the carrier all the rf cycles are at full power all the time. With
voice the rf reaches the same power levels but it is turned on and off
by the voice. The power levels also vary with the amplitude of the
voice. At full modulation the power levels of the rf cycles reach the
same levels as they do with the carrier. They just don't stay there as
long.

Thus from the definition "average power contained in one rf cycle at
the crest of the modulation envelope". It tells you that the average
rf power is measured at the maximum part of the modulation peak or in
other words the maximum average power that the transmitter reaches on
voice peaks. (if only one rf cycle reaches that power level that
qualifies)

This is one reason why I say that it is important to realize that
there is no such thing as rms power. If you read the FCC definition of
pep it does not say rms power, it says average power. Lots of people
refer to power as rms power.
Lots of people get confused over this thinking pep is something else.

73
Gary K4FMX