[Elecraft] Re: Power measurement with a 'scope

[Ingo, DK3RED]

Hello Dan.

> ... How is QRPp measured using a scope and a dummy load ...

It's easy!

Step zero: Preparation
Connect the dummy and switch the K2 to transmit (press the key).

Step 1: Vpp (peak-to-peak voltage)
Messure the peak-to-peak voltage on the dummy with the scope.
i.e. Vpp = 14.14 volts

Step 2: Veff (effective voltage)
Veff = 0.707 ( Vpp / 2 )
Veff = 0.707 ( 14.14 / 2 )
Veff = 5 volts

Step 3: R (resistor/dummy)
R = 50 ohms

Step 4: Power (output)
P = (Veff * Veff ) / R
P = (5 * 5 ) / 50
P = 0.5 watts
P = 500 milli watts

-- 
72/73 de Ingo, DK3RED   Don't forget: the fun is the power!
   dk3red@t-online.de   http://www.qsl.net/dk3red
       DL-QRP-AG #824   http://www.dl-qrp-ag.de