Need clarification on measurement scheme

Nov 25, 2017 4 Replies

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dakupoto 8 years ago

Could some electronics guru here please clarify the following ? I have the SPICE model for a 1:4 Guanella balun. The signal end resistance is 10.0 Ohm, and the floating output resistance is

40.0 Ohm. To measure the input/output power, I am measuring the input/output current/voltage and computing the RMS power. Is this the correct way to do the power measurement. The RMS values for current/voltage values are computed from the raw sata values with a simple C program. Any hints/suggestions would be very helpful. Thanks in advance.

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Winfield Hill 8 years ago

Yes. The Guanella balun should be a perfect transformer, within its operating range, provided it's wound with 20-ohm coax, etc. Then you can scale the output load voltage/current by 0.5x/2x to analyze the signal load, etc.

Thanks, - Win

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Joerg 8 years ago

It would also help to detect how much voltage and current are out of phase. If the raw sampled data is available for voltage and current that would be easy to do.

Regards, Joerg http://www.analogconsultants.com/

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dakupoto 8 years ago

I am afraid instead of "Then you can scale the output load > voltage/current by 0.5x/2x" it should be "Then you can scale the output load

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Jeroen Belleman 8 years ago

That question is surprising, because it seems so evident:

Z0 = 2*Zin or Z0 is 0.5*Zout. Either way, it's 20 Ohms. At the input, you have two lines in parallel, which must make 10 Ohms. At the output, you have two lines in series, which must make 40 Ohms.

Jeroen Belleman

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