# Ham Radio - Measuring the Cricket 40 output power with my oscilloscope.

Discussion in 'Amateur Radio News' started by KB7TBT, Dec 31, 2019.

1. ### KB7TBTHam MemberQRZ Page

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2. ### PA0MHSXML SubscriberQRZ Page

There are a few "errors" in your video, if I may call them that. First: the resistance of your dummy isn't 56,4 Ohms, that is the impedance. You're also reading an X value with your VNA of -1.2Ohm. Further, while the input resistance of your scope is 1MOhm, the impedance is far from that. Your scope also has a capacitance of 20pF, which presents an impedance of 1136Ohms at 7MHz. So the total impedance the Cricket sees is 53,7 Ohm.
Regarding the value of the sine wave: you don't use the average value because the average or mean value of a sine wave is 0V. The value used for power calculations is the effective value, which represents the equivalent DC value producing the same power. Going from peak-to-peak to effective: Veff = Vpp / (2 * √2).

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3. ### AF7ECHam MemberQRZ Page

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