A 'watt' is a measurement of the amount of work being done. Electrically, it's defined as the amount of work being done by 1 volt with 1 ampere of current flowing.
If you have a circuit that is flowing 1 amp at 1 volt then the work/power being done is 1 watt.
The difference between an 'average' watt and a 'Pep' watt is in how 'fast' you are doing the measuring, or, how much the work varies in a unit of time. For instance. A constant carrier signal is just that, constant. Doesn't vary in magnitude. ('Dead key') But, when you modulate that constant carrier, put an audio signal on it, then the amplitude of the signal changes with the frequency of the applied signal (voice/tone/whatever). If you happen to do the measuring at a voice/tone peak, it will be more watts than if you measure it during a tone/voice 'minimum' {a voice can be considered an AC signal since the tone varies according to how fast (frequency) the vocal cords are vibrating (oscillating)}. An 'average' watt meter sort of averages those peaks/valleys over a period of time longer than the time for one full cycle of that voice 'oscillation'. That's because of the way a typical mechanical meter works, it isn't very fast moving, takes time for that current flowing in the meter to make the needle do any moving. [Sheesh, getting sort of involved, huh?]
When you consider an electrical circuit you are usually only interested in the maximums. That way you can design the circuit so that it's strong enough to handle that much power, sort of. Or you want to know what the maximum power is, right? So, all them 'low' spots don't really interest you. So, you design a meter that only reads the maximum values, only reads the "peaks" of the signal, and ... ... "TA-DA!" ... you got a 'Pep' meter. The same amount of power is being produced or transmitted. The only difference is in how, or "where" in the cycle of that transmitted signal the measurement is taken. An average meter and a Pep meter show different readings for the exact same watt that's coming out of the transmitter (or amplifier). The only practical difference between the two is the 'size' of the number. There is a definite relationship between those two numbers, average watt and Pep watt. If you know what that relationship is, you can calculate one from the other. (A pep watt is about 1.4 times the 'size' of an average watt. So 100 average watts is about 140 Pep watts.) Why use an averaging meter instead of a Pep meter? Because that's what you happen to have. What happens if you use a Pep meter to read a constant or continuous signal, no variations from applied modulation? You get the same reading as the averaging meter gives (or should), since there's no peaks and valleys, or it's all peaks, whatever. The confusion comes in because people seem to think that a watt changes in size. It doesn't. Only in how it's measured.
That's all a generalization. Nothing absolutely 'exact', but close enough for government standards, sort of.
- 'Doc
((If you are after 'bigger' numbers, just lie about it. Much cheaper/easier than not.))
Oh, one last thing. I'm on my first cup of coffee. If the numbers are wrong it's because it's my first cup of coffee. If I check it later I may change or correct it.. if I remember. The general idea is true, the rest is subject to more coffee.