OK, in order to try to understand these claims better, I've performed a test measurement to see if I have it correct in my head, I just learned some things.

I measured the input/output of a transformer. Sine wave input from function generator, 10 Ohms in series with the primary and 330 Ohm resistor load across the secondary.

I used the vrms measurement on my DS1000E Oscilloscope and measured 45.7 mV across the 10 Ohm resistor and 97.7 mV across the input to the primary,

the phase angle between the voltage and current waveform was 11 degrees. So from that I get a power factor of 0.98 by cos(11) = 0.981.

And I get the current by dividing the 45.7 mV by the 10 Ohms to get 0.00457 A then I multiply that by the voltage across the primary which is 97.7 mV = 0.0004464 Watts

I then multiply that by the power factor of 0.98 to get 0.0004375 Watts input power.

To get the output I measured 294 mV across the 330 Ohm load the current was 0.00089 A, multiplied by the 294 mV = 0.0002616 Watts Output.

Not sure if I'm supposed to measure and phase difference in the output.

So I get 0.0004375 Watts input and 0.0002619 Watts output which output divided by input = 59.8 % efficient.

What do I do wrong, if someone wouldn't mind pointing it out.

I'm very much a learner, I need feedback.

The low efficiency would be due to driving that transformer incorrectly (not enough voltage, wrong frequency), frequency was about 200 kHz.

Oh and the difference in phase between the secondary voltage/current and primary voltage was 6 degree's (I think) Not sure if that actually means anything.

Cheers

I think something is wrong because if I consider the power dissipated by the resistors I get for the 10 Ohm resistor, 0.00457 A x 0.0457 V = 0.0002 W

and the 330 Ohm resistor I get 0.00089 A x 0.294 mV = 0.0002616 W plus the 0.0002 W = 0.0004616 Watts dissipated. But the input was only 0.0004375 Watts.

Must be measurement error, calculation error or OU, I would guess one of the first two.

I suppose I will need to re-do the measurements and the calculations, the numbers won't be the same though because I changed the FG settings and it will be difficult to

get them the same again. I'll use more power anyway.

..