I made a measurement using signal generator 33220A and AC level meter
34410A.I generated 150 kHz/0 dBm with 600 ohms load setting. Then I tried to measure with a level meter and there the meter reads 10 dBm!
Could anybody explain how it happens and how to solve it! I have already checked with different terminations and load settings but the results remains the same.
Will there be any reason apart from being a defective meter?
Best Regards
ref:
log(600/50) = 10.8 ..hmm..
-- - Blarp the Enigmatic
:)
I think I found the reason, I also need to set the reference load resistance value for math calculation of dBm in AC Level Meter, see on page 69:
dBm Measurements The dBm operation calculates the power delivered to a resistance referenced to 1 milliwatt. dBm =3D 10 =B4 Log10 ( reading2 / reference resistance / 1 mW ) Applies to dc voltage and ac voltage measurements only. =B7 You can choose from 17 different reference resistance values. The factory setting for the reference resistance is 600W. The choices are: 50, 75, 93, 110, 124, 125, 135, 150, 250, 300, 500,
600, 800, 900, 1000, 1200, or 8000 ohms. =B7 The reference resistance is stored in non-volatile memory, and does not change when power has been off or after a remote interface reset. =B7 Front-Panel Operation: After enabling dBm, you can select a new reference resistance by pressing Shift > (Menu Recall). Turning on the menu does not disable the dBm operation; the multimeter will resume taking measurements when you turn off the menu. 4: dBm REF R (MATH MENU)It is not a big issue but sometimes the multimeters having many options makes me quite confused. It is the kind of task that I have never worked on before. However I enjoy working here in this new job as I have to deal with those small little akward practical problems and I believe I will get used to it with time.
Regards
"reference resistance is 600 WATTS"???????
It's a cut and paste problem, if you look at the original doc, p41, it does use the omega symbol, which seems to get transmogrified to a W
martin
Have you tried looking at the signals with a 'scope? George
ref:
Now it is all solved. It is just a kind of adjustment problem. The signal generator output should be adjusted for 600 ohms termination, and the ac level meter should also be measuring accross a 600 ohms termination.At the same time the dBm calculation should be based on 600 ohms load. This solve the whole mismatch problem.
Thanks for suggestions and discussions
Regards
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