[Elecraft] P3TXMON question?

[Don Wilhelm]

Bill's information is entirely correct.  Thank you for that clear 
explanation.

Now back to what I think was the intent of the original question - even 
if the terms were incorrect.
Hams commonly use two different considerations for power - PEP - Peak 
Envelope Power - that is the peak power that we (at least here in the 
US) need to use when considering our power limits, and that is the 
specified power output for most if not all amateur transceivers and 
amplifiers.

The other term is Average Power, and we can use that for a measure of 
the amount of compression used in SSB transmissions - more compression 
will bring the Average Power up closer to the PEP, but too much will 
create muffled speech (listen during a SSB contest for the 
unintelligible signals using too much compression).

As Alan Bloom indicated, the narrow bar indicates the PEP value, while 
the other bar will be more of an indication of Average Power, although 
your eyes may have to interpret the movement to determine the real 
average because that indicator will be constantly changing with SSB 
speech patterns, but for CW and data modes, the PEP and average should 
be equal during keydown intervals.

73,
Don W3FPR

On 8/21/2015 3:34 PM, Bill Breeden wrote:
>
> It's important to remember that RF power expressed in watts is always 
> based on RMS values.  If RF watts are calculated by measuring the 
> voltage across a known load, the voltage must be expressed as an RMS 
> value to correctly calculate the power in watts.  Watts are watts.  
> There is no such thing as "peak to peak" or "RMS watts" when 
> expressing RF power in watts.
>
> Peak envelope power (PEP) has nothing to do with the difference 
> between the peak and average voltage of a sine wave.  It is the 
> measure of the power of an RF signal at the modulation peak, averaged 
> over one RF cycle.  The power measurement within that one RF cycle is 
> still based on RMS values.
>
> 73,
>
> Bill - NA5DX