[AMPS] Peak Power Meters - some more thoughts

Jon Ogden jono@enteract.com
Thu, 24 Jun 99 15:45:30 -0500


Stepping aside from the enlightening discussion on tube gain vs. plate 
voltage, I want to come back to the original poster's question of why his 
peak power meter read differently at CW than at SSB.

I don't know why I didn't think of this before, but I remembered some 
stuff from when I had my engineering days.

We used HP power meters in our labs and with one CW tone (say at 5 dBm), 
the meter would read one power level.  If two tones were measured such 
that the total power out was stil the same (each tone would be 2 dBm - 
half the power of 5 dBm), the meter would read differently (I forget 
wether it read higher or lower - I think it was lower).  This is due to 
the way in which the envelope of the signal is detected.  Note: These 
were VERY expensive power meters.

An SSB signal is in effect a much broader signal (than a CW signal) 
almost equivalent of a multi-tone environment.  The envelope detection 
circuitry on the power meter just might not be able to do a good job of 
detecting peak power that is broader than a CW signal.

IMHO, the best way to read the actual peak power is to read it with a CW 
signal.  This is what I always did in my design days.

73,

Jon
KE9NA


--------------------------------------------------------------------------
The Second Amendment is NOT about duck hunting!


Jon Ogden

jono@enteract.com
www.qsl.net/ke9na

"A life lived in fear is a life half lived."


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