Hi,
I have set up a a x10 probe to view on Channel 1 the waveform of a 3.5Mhz steady carrier from a transmitter as applied to a 50 ohms load for which the transmitter is designed.
I use the Measurement menu to display RMS of Channel 1.
I can now calculate the RF Power in Watts that is being dissipated in the 50 ohm load. W = (Vrms * Vrms)/50
Rather than using the calculator every time, I would like to think that I can display this calculated Watts value directly on screen using some kind of Math function but am struggling a little to see how to do it.
I thought I could setup a function, say F1 in the Math menu and use the RMS of Channel 1 as a source then just do the algebra on it. But the only sources available as inputs to any Math function are the Channels C1-C4, Equivalent Zoom functions, the other function F2 and the reference waveforms. I kind of thought I would see Vrms of Channel one as a possible input.
I have a feeling I am missing something really obvious but have had a good look , tried finding something on the web and am not making progress.
I wonder if someone could point me in the right direction to get a nice clear Watts indication directly on the screen?
Thanks
Eloso
How much power ??!!!!
You cannot apply more than 5V RMS which is 0.5W to scope input directly when in 50Ω mode...
You might need an attenuator..
Hi impedance probes are not really best way. Even if you insist to use Hi Impedance probe, you need to terminate source with 50 Ω load. Probes also have frequency derating factor.. And 15-20pF capacitance...
That being said first, if you put attenuator in the front of input set to 50 Ω, then make sure to set it as a probe factor in the channel.
Also, measurements are applied to channels (real and virtual, like Math and REF) not the other way arround.
You can enable FFT, set it in dBm mode and read power directly in decibels from marker table.