I build the CPK-4. It works very good! Not too chirpy. While adjusting the frequency I blew the 100uH inductor. Today I received some spares and fixed the transmitter.

Does anyone know how to measure the output power with a multimeter?

Hi Anton,

There is a good description of building a QRP power meter by Vk3ye on the internet, if you search for "Vk3ye qrp power meter".

I measured it attaching an oscilloscope to the dummyload for the transmitter. The multimeter was used to measure the transmitters power supply :-)

With only a multimeter you cannot measure the transmitters power output, unless you are going to be smart depending on the details of your meter.?

You could attach a dummyload to the transmitter, and build a diode detector to measure the peak voltage of your transmitter. Than use your meter to measure this, and do the math to convert it to output power.?

If you are really interested in measuring this, I would recommend to use this as an excuse to get myself an oscilloscope of some sort that covers your cpk's frequency :-)?

If you are in the Eindhoven area I could help. In that case please send me a direct message.

Berrie PB4PT.?

Hi Berrie,

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When I looked at that diagram, I suddenly realized that you can measure on a dummy load. And as it happens, this exact function is described for the dummy load from QRP Labs that I have sitting in the drawer.

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I measured 6,6V, so the output power would be around 0,4W

Bye and 73,

Anton

0.4 watt is very normal if you power with 9V.

Hi Adam,

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Great! 0,4W and 955km range ?

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73,

Anton

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Put a 50ohm dummy load and measure the voltage across it while transmitting , then use the formula for power using? the 50 ohms and the measured voltage ( P= V^2/R)